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Brick veneer is a very brittle material that cannot take much stress without cracking. Brick veneer is simply a protective exterior siding (weather barrier) and does not provide any structural benefit to the home. Underpinning the foundation because of cracks in brick veneer can be a waste of money.

Clay-fired brick are baked in a kiln (large oven) to thousands of degrees Farenheight and when the brick leave the oven they have absolute zero moisture content. The brick then spend the rest of their life taking on moisture which causes a dimension increase or expansion. In commercial buildings, architects employ the use of expansion joints alongside windows and doors and at periodic distances in long walls to accommodate this long term growth. In residential construction, this is never done because it is considered unsightly. Whenever you have long walls of brick veneer with multiple windows within the wall, the continuous panel of brick below the windows experiences more growth (expansion) than the upper intermittent panels of brick broken up by the windows. This differential expansion can lead to stair-step cracking below the windows. Many foundation repair contractors (and some engineers!!) will tell you that these cracks represent foundation failure and recommend foundation underpinning as a method of repair. This is completely untrue.

When the foundation settles differentially (unevenly) brick veneer can develop cracks. It takes very little differential settlement to cause brick veneer cracks. However, the wood frame building structure behind the brick veneer (most of the time) doesn’t care. If you don’t have cracks in drywall opposite the brick veneer cracks, then there is probably no problem or concern. Wood frame structures are extremely flexible and can endure much strain without excessive stress. The only way to determine when differential settlement is a problem is to perform a floor level survey. If the survey reveals fairly level floor conditions, then the brick veneer cracks are moot and nothing to worry about. The cracks can be left alone, caulked or repointed. The later requires a conscious effort on the part of the brick mason to match the mortar color; otherwise, the repair can look much worse than the bare cracks.

There are a host of other causes of brick veneer cracking including steel lintel expansion, steel lintel rust-jacking, shrinkage of cement-based brick, expansion of clay brick resisted by shrinkage of concrete or concrete masonry, shrink-swell of underlying expansive clay soils, and compression of brick veneer by shrinkage of the wood frame building structure.

Concrete is a mixture of sand, cement, gravel and water. The cement and water chemically react to cause the mixture to harden over time. During the hardening, there is a loss of water, so 1/4 of the original constituents disappears. This causes a loss of volume. Whenever concrete is placed in a thin sheet over a large foot-print area, the dimension change takes place over the foot print. As the concrete tries to contract or shrink dimensionally, frictional forces are generated at the bottom of the concrete and this creates tensile stresses in the concrete. Concrete is extremely strong in compression but fairly weak in tension. Hence, tensile cracks or shrinkage cracks will form to relieve the tensile stress. It is nearly impossible to prevent shrinkage cracks from forming so smart contractors will place steel reinforcement (such as wire mesh) in the concrete slab to resist cracking. In lieu of wire mesh, closely spaced contraction joints can be saw-cut into the freshly placed concrete to create lines or planes of weakness and force the shrinkage cracks to form at the base of the saw cut. If these two things are not done, the concrete slab will develop its own random, often-jagged, shrinkage cracks. This can lead to gapping in glued-down hardwood flooring or cracking in ceramic tile or adhered sheet vinyl. Many foundation repair contractors will tell you that these cracks are signs of foundation failure and recommend expensive underpinning repairs. Don’t be fooled, call one of our engineers to diagnose the problem.

Foundation Wall Cracks Most foundation walls in Alabama are constructed of concrete masonry or solid concrete. Some walls are unreinforced and others are sometimes lightly reinforced. Seldom do walls contain horizontal reinforcement in the form of rebar in concrete or joint steel in masonry. All concrete materials shrink in volume soon after construction due to loss of water upon drying/curing. As the concrete materials shrink, there is a corresponding dimension change that takes place. The foundation wall is typically bonded to the buried concrete footing so the shrinkage is well restrained along the bottom. At the top, the fairly light wood frame superstructure doesn’t provide much restraint. As such, vertical cracks will often form near the centers of long walls which are widest at the top and which narrow to hairline size at the base. These are called shrinkage cracks and they are usually structurally unimportant. (Note: another form of vertical cracking is caused by sweeping, inward bowing of basement walls which can be a problem/concern).

Stair-step cracks in masonry walls and diagonal cracks in concrete walls are often caused by differential foundation settlement.

The topography of some of our area consists of moderate to steeply sloping, wooded hillsides which generally have a shallow bedrock depth– this is especially true in areas where numerous boulders or bedrock pinnacles outcrop at the ground surface. House construction in this type of terrain usually requires extensive land clearing and the addition of fill soil to provide a level pad or acceptable base on which to construct footing and foundation walls. Moreover, because of the ground slope, houses are often constructed on crawl space foundations which bear on footings that stair-step “up and down” the natural and/or “artificially created” grade. Many times the footings are founded partly on rock and partly on soil. If the soil-supported footings settle and the rock supported footings do not, a differential settlement has occurred. Differential settlements are frequently the cause of foundation wall and brick veneer cracking; they are exemplified by stair-step crack patterns and/or crack patterns which indicate rotation or pivoting about a central point.

Foundation settlements occur whenever the bearing pressure of the foundation footing exceeds the strength of the supporting soil. Settlements also occur if the supporting soils are fill soils that have not been properly compacted, or if the underlying soils include mixed organics (vegetation) that decay over time. It is not unusual for foundations to rest on large tree stumps or root systems that were cut to the ground level.

Another common cause of foundation settlement or movement in our area is associated with underlying subgrade soils. These soils are usually residual clays that have evolved from weathered limestone bedrock. Geo-technical engineers classify these soils as “highly plastic” since they behave “actively” over a wide range of moisture contents. Plastic soils physically shrink in volume when they dry or desiccate, and swell in volume when they become wet. Inevitably, during the summer months foundations tend to settle, causing cracks in foundations and brick veneer; during the winter months the cracks disappear. Proper site drainage is imperative in this geologic/topographic area because the soils should maintain a uniform moisture content. If water stands or collects in low lying areas near foundation walls, the subgrade soils can become and/or remain saturated even as adjacent soils dry.

Regardless of the cause, the potential for long term differential foundation settlement is very good in our area. Thus, in new house construction, it is imperative that footings are located on stiff underlying subgrade soils– preferably deep in the ground, below seasonal drying penetration–and that proper drainage is provided to prevent water from standing and soaking into the ground around the home (saturating the supporting subgrade soils). Of equal concern is water that flows along the foundation walls; it can lead to erosion undermining.

Perhaps the most catastrophic failures that we’ve witnessed in our inspection careers have been fully-inward-bulged (collapsed) basement foundation walls. Each failed wall (made entirely of hollow core concrete block) literally exploded into the basement followed by a river of mud or earthen landslide. If anyone had been sitting or standing near the wall at the time of failure, we doubt they would have survived. Fortunately, we’ve never heard of a serious injury or lost life, but we have witnessed the emotional grief/anguish that ensues once the homeowner finds out that their insurance policy will not cover the cost of cleanup or repair. Obviously, these costs can easily exceed tens of thousands of dollars.

A typical basement foundation in Alabama seems to consist of a poured-in-place concrete footing supporting a hollow-core, concrete block wall. Usually, the basement floor slab is placed on top of a bed of gravel (called a floating slab) and this slab directly abuts the lower edge of the basement foundation wall. This floor slab is actually critical to the long term performance of the basement foundation because it provides crucial lateral support along the bottom of the wall. A pressure-treated, wood sill plate (called a mud-sill) is then bolted to the top of the basement wall and the home’s overlying wood-frame floor system is usually secured to this sill plate. This wood frame floor system is also crucial to the long term performance of the basement wall because it too provides important lateral restraint along the top of the wall. Hence, basement walls are laterally supported along their top and bottom edges.

Whenever backfill soil is placed against a basement wall, it exerts lateral pressure against the wall. This external lateral pressure tries to bend (bow) the basement wall inward-between the top and bottom supports (restraints). Whenever the lateral pressure is so great that the basement wall begins to bulge inward, a long horizontal crack will form-especially if the basement wall is made of hollow concrete block. Again, this seems to be the construction material of choice in North Alabama; we seldom see solid-poured concrete walls. Once this horizontal crack forms, the basement wall has lost all appreciable lateral resistance, so the wall is extremely vulnerable to an inward bulging failure at anytime. Hence, the tell-tale clue of a serious basement wall problem is a long horizontal crack near the mid-height of the wall. This crack will typically transition into both ascending and descending stair-step cracks near the ends of the wall-i.e. near the basement corners because the adjacent side walls act like buttresses and prevent inward bulging deformation.

The amount of lateral pressure exerted by “backfill” is based on the type of backfill material. Heavy clays and silty clay soils tend to exert large lateral pressures, whereas clean sands and gravels exert fairly small lateral pressures. The basement’s worst enemy, however, is usually not the soil backfill material but water. If water ever builds-up in the soil backfill, it exerts “hydrostatic pressure” against the basement-just like the pressure that water exerts on a lake’s dam. Hydrostatic pressure is usually two or three times greater than the lateral pressure exerted by backfill. Hence, an important construction feature of any basement is to have an adequate exterior drainage system-usually called a footing drain. Moreover, the ground surface around the home should be graded so that it slopes away from the home, and the roof should be complemented by well-maintained and fully functional gutters. These features are necessary to ensure that large amounts of water never reach the backfill zone around a below grade basement.

Another problem with silty clay or clay soil backfill materials is that they tend to impede the flow of surface water down to a footing drain, because they are generally impermeable and they tend to absorb and hold water. Sands and gravels, on the other hand, allow surface water to flow freely down to a footing drain. Hence, the backfill material of choice is sand or gravel. Unfortunately, most builders backfill the basement with the original soil that was excavated-and in North Alabama this is generally silty clay or clay.

If there is no footing drain surrounding the basement and/or the drain does not gravity flow to daylight (into the air somewhere down grade), then hydrostatic pressures will likely build-up outside the basement and failure will likely occur at some time.

The current Building Code provides important structural information regarding basement wall construction. What you’ll find when reviewing this table of information is that the common, 8-inch wide, hollow core, concrete block basement wall just isn’t suitable for below grade basement wall construction-at least for backfill heights exceeding four to six feet. Most below grade basement walls support backfills of seven or more feet. The Code would require that these basements be constructed of reinforced concrete block or solid-poured concrete.

The most common causes of floor sag in residential and commercial buildings is mis-aligned load-bearing walls and long spanning floor joists and/or beam girders. It is not unusual for a home or commercial building to have a central hallway area that parallels the front and rear walls in the long direction. The floor joists and ceiling joists and roof rafters will all span in the short direction across the home. The ceiling joists will typically span from the front/rear to the hallway walls making the hallway walls load-bearing. The front/rear roof rafters will also typically be braced to the hallway walls making them even more load-bearing. If there is one central beam girder located near the center of the hallway, the two hallway walls can overload the floor joists which frame into the center beam and cause floor sag. This more often occurs when the floor beam is located beneath one of the hallway walls. The other hallway wall will overload the floor joists and cause sag. Another cause of floor sag is whenever tall walls, like foyers or great rooms, overlie floor joists which have long spans. If the joists are not designed for the extra heavy weight of the tall wall, they can sag.

Similar to floor sag, ceiling sag is usually caused by long spanning ceiling joists or main beams which support the ceiling joists over large rooms. Also, similar to floor sag, having load-bearing second floor walls located above the mid-spans of the lower level ceiling joists can cause ceiling sag.

There are two primary roof framing systems used by builders: rafters and trusses, as well as two primary roof shapes: gables and hips.

Rafter-framed roofs consist of individual rafters (sawn lumber members), usually spaced from 12 to 24 inches on center, which span from the exterior walls or roof-eaves up to the roof top or ridge, or into the sides of the main hip rafters. This style of roof construction is often called “stick-framing”. The most common rafter size is a 2×6; unfortunately, this small-size member cannot span very far and must typically be braced near mid-span. A structural analysis will usually show that the roof-bracing system picks up most of the roof load (weight). Hence, it is very important that the roof braces land (rest) on only designated interior “load-bearing” walls. Unfortunately, it appears as though many builders/framers do not realize this since they often support the roof bracing systems on the closest or most convenient interior room partition wall. This can lead to long-term floor and roof sag because most floor joists are not sized for roof loads.

The ridge board located along the peak of the roof typically does not provide any structural support for a rafter-framed roof system; it simply serves as a convenient bearing-plate or nailing plate for the opposing rafters. However, it is important (and a Code requirement) that the ridge board be deep (tall) enough to provide full contact to the cut face of the mating rafter and that opposing rafters meeting at the ridge directly align with one another. Whenever the ridge board is non-structural, it is absolutely necessary that the roof rafters be lapped alongside and connected to the underlying ceiling joists at the exterior wall plate; moreover, the ceiling joists that extend across the home must be properly lapped and connected to one another because they provide a critical “tension-tie” across the home. If the ceiling joists do not provide this critical tie or if they span transverse to the roof rafters (which is often the case), the roof ridge will likely sag and the exterior walls will likely lean outward.

The latter is a common problem with stick-framed cathedral roofs/ceilings. In this type of roof system, the rafters and roof decking also serve as the interior ceiling. Since a conventional rafter-framed roof exerts outward forces on the supporting exterior walls, a structural ridge beam (board) is required for cathedral ceiling construction because there are no ceiling joists to provide the normal cross-tie. In other words, if the ridge beam is capable of providing vertical support to the rafters, then they do not exert an outward thrust on the supporting exterior walls. A structural ridge beam normally consists of either glue-laminated timber (glu-lam), laminated veneer lumber (LVL) or structural steel. Seldom will a solid-sawn lumber beam or built-up lumber beam suffice-especially for long ridge beam spans.

Failure to provide a structural ridge beam in cathedral ceiling construction always results in roof sag and corresponding outward lean in the exterior walls which support the rafters. Although I have never witnessed the collapse of an improperly constructed cathedral ceiling, I suspect that it can happen. The reason why complete failures don’t occur is probably because the distortions that slowly develop inside the home, from leaning walls and sagging roofs, gives the homeowner plenty of time to hire a professional to develop a corrective repair. Hence, this condition should never be ignored, no matter how slight the distortions.

Truss-framed roofs consist of pre-engineered, light-gage-metal-plate-connected sawn lumber members which are fabricated inside a controlled environment, per some proprietary engineering design and delivered to a construction site on flat bed trucks or special “cradle trailers.” These structural units/frames are designed to withstand numerous Code-specified structural load combinations and, because of their engineering and close fabrication tolerances, often provide the best solution to complex roof shapes or difficult roof framing configurations. Trusses usually transfer all of their load to the outer bearing points (exterior walls); because of this, they do not need any support from interior room partition walls. Because roof trusses are designed to span across the entire width of a home, the top chord of the truss and oftentimes many of the interior web members are placed into compression. The compressive forces try to make the truss members buckle or distort out of plane and, unless they are properly braced and held straight during erection, the entire truss may warp and distort. This can lead to reduced load-capacity, increased deflection, and the possible transfer of roof load to interior room partition walls. Once the roof decking is nailed to the truss assembly, the top chords become permanently braced. The very long compression web members (interior diagonal members between the top and bottom chords) still require some sort of permanent bracing to prevent them from distorting. Many home builders and framers do not realize this. Another problem with trusses is that very long/large trusses are usually flimsy and somewhat fragile and hard to handle at the job site. Unless the trusses are handled and stored very carefully in the field, and later during actual erection, the metal-plate connections may detach from the wood members. If this occurs, the truss has been compromised and will no longer behave as designed unless repaired properly/immediately. Also, if any truss member(s) are cut or damaged during construction or later by other trades (electricians, plumbers, HVAC), the truss will be compromised and rendered somewhat ineffective. In either case, the end result is usually roof distortion, ceiling distortion or the creation of isolated floor sag.

Cupping, also called washboard is a condition where the edges of a piece of flooring (across its width) are high and the center is lower. This generally develops gradually. Moisture imbalance through the thickness of the flooring is the only cause. Moisture is greater on the bottom of the piece than on the top.

A common source of this moisture is a wet basement or crawlspace. This moisture rises up into the home due to what is called the “stack effect” and this creates high moisture conditions on the bottom face of the hardwood flooring. This in turn causes the bottom face of the hardwood boards to expand dimensionally and this creates the cupping condition.

The most common source of moisture inside a crawl space is related to a combination of moisture vapor rising out of the uncovered ground and warm, high-humidity, air entering the crawl space through the perimeter foundation vents during the summer months. Whenever warm, humid air enters the crawl space, the warm air temperature drops about 20 degrees or more since the temperature in the crawl space is much cooler than outside air. When the temperature drops, the warm, humid air must give up its moisture and this moisture condenses on cool objects such as air conditioning ducts, the wood floor (exposed to interior air conditioning) and the ground surface. As this moisture collects, the humidity in the crawl space increases. Wood is a hygroscopic material, meaning that it tries to reach a moisture equilibrium with the surrounding atmosphere–either absorbing moisture in high humidity or off-gassing moisture in low humidity.

I’m sure many of you have watched a homeowner and home inspector express concern about cracks in ceramic tile flooring. Any type of random, jagged crack inside a home creates alarm in a buyer and there is nothing more disturbing than cracked ceramic tile. It also detracts from the appearance of an otherwise beautiful flooring material. Included are the most common causes of ceramic tile cracks and possible solutions to correct them.

Cracked ceramic tile flooring occurs on both concrete slabs and wood floors. Whenever tile cracks over a concrete floor slab, you can bet dimes to dollars that the crack in the tile is a reflection of a crack in the underlying concrete slab. Since the tile is tightly bonded to the underlying concrete, any crack which forms in the concrete will surely reflect or propagate through the attached tile. Nine times out of ten, the cause of the concrete and tile crack is shrinkage of the underlying concrete slab. There is no way (it is nearly impossible) to pour a large concrete floor slab, like the foot-print size of any a exp ect shrinkage cracks to form. Smart builders will insist that concrete finishers use control joints (saw cut straight line grooves in the concrete) to force the shrinkage cracks to form at the grooves. When this is done, the ceramic tile can be laid on the floor so that the saw cut grooves (control joints) align with the grout joints in the tile. Instead of placing grout in these joints, a colored, flexible caulking is placed in the joint to allow the joint to open/close with the crack in the underlying concrete. If control joints are not saw-cut into the concrete slab, then random shrinkage cracks will form. If tile is adhered to the concrete, then the tile will crack with the random shrinkage cracks in the concrete slab. The only way to avoid this, and to repair the cracked tile once it occurs, is to place a “crack isolation membrane” between the concrete and ceramic tile. For more information about crack isolation membranes, visit the following Internet link: http://www.noblecompany.com/pdf/CISDT800.PDF

The other cause of tile cracking over concrete slabs is related to settlement cracking in the concrete slab foundation. These cracks are usually larger than shrinkage cracks and can often be distinguished from shrinkage cracks by looking for settlement cracks in the surrounding walls. When concrete slab foundations settle, cracks usually form in the walls above window and door openings. Settlement cracks can also be verified by performing a floor level survey. Significant settlement may require foundation repair.

Whenever cracks in ceramic tile form over wood floors, the cause is generally two fold: either the floor system is expanding and contracting excessively from seasonal moisture changes or there is a floor structure problem (e.g., excessive floor deflection). The Tile Council of America (TCA) and American National Standards Institute (ANSI) have long argued that ceramic tile should not be placed over OSB subflooring, which is probably the most common type of floor sheathing material used today. Until 2005, the TCA recommended that tile only be placed over plywood subflooring. In 2005, they developed detail F155-05 which allows the use of OSB subflooring in residential applications. However, they still require that a second layer of plywood (underlayment) be placed over the OSB. Our firm has inspected a large number of cracked ceramic tile floors that had cement backer board placed over OSB subflooring, and in nearly all cases, we concluded that the cracks were related to movement in the OSB subflooring. This movement is caused by seasonal humidity changes, especially when the floor overlies a ventilated crawl space or unconditioned basement. The cracks in the tile will typically form in orthogonal patterns that usually reflect the panel joints in the underlying OSB or cement backer board. Whenever these types of cracks develop, the homeowner is faced with either accepting the cracks, trying to control seasonal moisture changes in the subflooring, or removing the tile, replacing the OSB subflooring with plywood, and reinstalling the tile. If the later is done, then the tile should be installed in strict accordance with one of the Standard Installation Procedures described in the TCA Handbook for Ceramic Tile Installation. This document can be purchased from TCA by phone at 864-646-8453. If you plan to have ceramic tile flooring installed in your home, insist that it be installed per one of TCA’s approved Installation Methods.

Most of the retaining walls throughout the state consist of concrete block masonry. The remaining are dominated by brick or rubble stone masonry walls, solid poured concrete and segmental concrete block. The most critical (dangerous) retaining walls are those over four feet tall. At this height, the lateral forces behind the wall become substantial and hollow-core concrete block has a difficult time resisting these lateral forces. The end result of an improperly constructed wall is gradual, forward tilting, followed by eventual collapse. The latter normally occurs during rainfall.

There are basically two types of retaining walls: gravity walls and cantilever walls. A gravity-type retaining wall is usually made of heavy materials like concrete or concrete block and is very wide at the base and generally built into the excavation with a “batter” (it tapers to a smaller width at the top). By virtue of its massive weight, this type of wall is able to resist the overturning and sliding forces created by lateral soil pressure. Cantilever retaining walls are tall, relatively thin walls that rely on embedded steel reinforcement and connection to a wide footing to provide resistance to the lateral pressures exerted by earthen backfill. These walls are typically solid concrete or concrete block which are filled solid with concrete. A cantilever retaining wall has an inverted T-shape, consisting of a vertical stem to retain the soil and a large (wde) footing to prevent sliding/overturning. The weight of the soil bearing on the heel of the large footing acts as a counterbalance, resisting lateral earth and hydrostatic (water) pressure. The stem of a cantilever retaining wall is steel reinforced to resist the lateral forces against it. In addition, the footing and stem must be properly connected with steel bars (so that the stem cannot rotate on the footing.)

Most of the leaning retaining walls we see are the ever popular, concrete block retaining wall. This wall generally consists of either 8-inch or 12-inch thick (wide) concrete block, laid in full-head and bed mortar joints, resting on some sort of continuous, poured-concrete, footing. If the wall is of hollow core construction, then it is severely limited with regard to long term performance for wall/backfill heights exceeding three or four feet. If the wall is filled with concrete and reinforced with steel, it is still severely limited if it is not connected (tied) to the supporting concrete footing. This can only be accomplished by using properly-sized, steel rebar dowels securely embedded in both the footing and the wall. Even if the wall is tied to the footing with steel dowels, the wall is still worthless for backfill heights exceeding about five feet, if the concrete footing is only made about two feet wide. And there’s the rub. Based on our experience, most leaning retaining walls, no matter how tall, are usually constructed on two-feet wide footings. We’ve concluded that builder’s apparently consider this “standard foundation footing width” also adequate for retaining wall construction. Unfortunately, it’s not.

The reason why these improperly constructed retaining walls are so lousy is that their dead weight, which can be modeled as a force vector pointing down, toward the center of the earth, acting through the wall’s center of gravity, cannot counteract or resist the horizontal force vector exerted by the earth backfill (soil pressure) on the wall, when both vectors try to rotate about the outer (front) edge of the footing. The lateral force vector dominates, especially when the backfill soil is a native clay which has a tendency to retain water. Hence, these walls cannot act like “gravity-type” retaining walls. They are not “massive” enough. If the block wall is left hollow, it simply breaks or separates along the base (bottom) mortar joint and topples or slides forward-often in a catastrophic fashion.

Drainage conditions also play a large role in success or failure of a retaining wall. If water is allowed to collect behind the wall, the horizontal forces increase substantially. Poor drainage conditions are usually the reason most wall failures occur during rainfall. Drainage is improved by backfilling the wall with gravel/sand, installation of a foundation drain, proper terrain, etc.

If properly constructed, however, relatively “thin” (8- to 12-inches thick) concrete block retaining walls are capable of resisting lateral pressure. These walls are called “cantilever retaining walls”. The name implies that the vertical wall segment “cantilevers” out of the footing. In other words, the base of the wall is rigidly attached/connected to the footing.

“So how do you build a safe, concrete block, cantilever retaining wall?”

Well it’s simple: you build a properly sized and reinforced footing and stem-wall, and rigidly connect the two! The former will usually have a footing width equal to about 60 to 75 percent of the wall height. Hence, a six foot wall may require a 4-1/2 foot wide footing; an 8-foot tall wall may require a 6-foot wide footing, and a 10-foot wall may require a 7-1/2 foot wide footing, etc. The actual size of the wall and footing should be determined by an engineering analysis which takes into account: the bearing capacity and shear strength of the supporting (underlying) soil; the strength properties of the wall and footing; the type and height and slope of the soil backfill that will be placed behind the wall; and, the drainage conditions that will exist behind the wall. In cantilever retaining wall construction, most of the footing width is actually extended back behind the wall, beneath the backfill. The dead weight of the backfill, acting down on this footing “heel” is what gives the “cantilever retaining wall” its “stability”. In other words, for the wall to tilt forward, the footing must be pulled up through the backfill soil.

“What can be done about leaning retaining walls?”

If you know of a fairly tall (more than 4 or 5 feet) concrete block retaining wall, that is leaning, have it inspected by an engineer. Since a properly designed/constructed wall shouldn’t tilt or lean forward, an engineer must determine whether the existing wall is safe and/or if it can be salvaged. Typical enhancements might consist of converting an existing masonry wall into a “gravity wall”; installing tie-backs or dead men anchors that extend back into the natural embankment; or constructing closely-spaced, buttresses against the wall. In some cases, where money is limited, it might be prudent to simply remove the wall and consult with a soil scientist or geotechnical engineer on how to construct a stable, exposed (sloped), soil embankment.

For those wanting to read more about the three different types of retaining walls, the National Concrete Masonry Association (NCMA) has published a series of articles, TEK Notes numbers 15-8 (Stock 91), 15-7A (Stock 97), and 15-6 (Stock 96), each costing $ 1.00. These explain the proper construction procedures and design principals for cantilever, gravity and segmental retaining walls. You can contact the NCMA and order the articles by telephone (703-713-1900) or by visiting their website at www.ncma.org.

Six people died May 8, 2000 in Roslyn Heights, New York after a Long Island homeowner disconnected his carbon monoxide detector because he thought its repeated buzzing was due to a malfunction. The air conditioning system pulled carbon monoxide gas from an adjacent natural gas furnace and spread it throughout the home while they slept.

In Minnesota a jury in February awarded two parents $1.9 million after their two children were killed by carbon monoxide poisoning in their recently-purchased home. The jury found the former owner of the home and the real estate company that helped him sell it liable in the wrongful death lawsuit because a previous home inspection had identified a problem with the furnace that was not disclosed to the new owners.

Carbon monoxide (CO) is a colorless, odorless, tasteless, deadly gas. Slightly lighter than air, it can quickly spread throughout a home. It is produced when any fossil fuel burns incompletely. During incomplete combustion, carbon and hydrogen combine to form carbon dioxide, water, heat and deadly carbon monoxide. In appliances that are properly installed and well maintained, the fuel burns cleanly and produces only small amounts of carbon monoxide. Anything that disrupts the burning process or reduces the supply of oxygen can increase carbon monoxide production. Some fuels, no matter how well they burn, produce copious amounts of carbon monoxide. These include wood, coal and charcoal. Gasoline engines also produce CO.

The U.S Consumer Product Safety Commission (CPSC) has identified carbon monoxide as the leading cause of gas poisoning deaths in the United States. The reason that carbon monoxide is so dangerous is because of its attraction to hemoglobin in the bloodstream. When breathed in, CO replaces the oxygen which our cells need to function. When present in the air, it rapidly accumulates in the blood, causing symptoms similar to the flu, such as headaches, fatigue, nausea and dizziness. Unlike flu, however, prolonged exposure leads to brain damage and death.

Modern construction practices tend to compound CO problems because today’s homes are air-tight. This is done to make them energy efficient, but it also keeps fresh air out. Older homes can also become starved for oxygen. The installation of a gas-burning appliance, for example, in a home already starved for fresh air can create a situation in which carbon monoxide is sucked out of exhaust flues into the house. Also a lack of fresh air in the home can cause natural gas, for example, to burn poorly since any flame needs oxygen to burn.

Since any burning fuel gives off some level of carbon monoxide, venting is extremely important. Make sure vents for furnaces and gas appliance are clean and free of obstructions such as bird’s nests and leaves. It doesn’t have to be wintertime for carbon monoxide to be a danger. Appliances that burn gas, such as ranges and water heaters, can also give off lethal amounts of carbon monoxide if not properly installed and maintained.

How efficient is your kitchen range? Carbon monoxide from kitchen ranges is a common reason for elevated concentrations of CO in homes. Kitchen ranges are required to produce no more than 800 parts per million (ppm) carbon monoxide in an air-free sample of flue gases. But continued operation of a kitchen range producing 800 ppm in a tight house without adequate ventilation will cause CO levels to rise quickly to unacceptable levels. Most kitchen ranges can be fine tuned to produce less than 50 ppm.

How can the adverse health effects from using a gas range be reduced? Do not block air vent holes. Do not cover the vent holes on the bottom of the oven with foil. Keep the unit clean. Do not operate with the oven door open. Never use a kitchen range to heat the home. On some cold morning, there might be the temptation to quickly heat the kitchen with the flame of the gas range. You know, just to knock the chill down. Don’t! First, the broiler and oven burners are designed to burn with the oven door closed. Opening the door disrupts the air flow pattern, and high concentrations of CO may be produced. The oven burner is not designed to operate continuously, and can overheat. Perhaps most important, kitchen ranges are designed for intermittent operation. Range standards allow concentrations of carbon monoxide that, under continuous operation, could create serious health problems.

Don’t think that just because your range is new that it won’t produce carbon monoxide. The 800 ppm CO limit has been in place since 1926. A new range might even emit more carbon monoxide than an old one. The best thing to do is have your range, old or new, tuned by a qualified contractor, one who has the proper instruments to measure carbon monoxide in the flue gases. Get your range checked immediately if you notice any of the following signs: Burner flames are not blue (this is not a foolproof indicator of proper burn, though, since even blue flames produces carbon monoxide); the burners do not light properly; burners or pilot produce soot; carbon monoxide levels in the house rise while the range is in use.

How about electric ranges? The electric heat elements do not produce combustion pollutants. Burning food, however, does produce carbon monoxide and can set off carbon monoxide detectors. If this happens, open the windows and leave the house until concentrations drop. CO is toxic so alarms should always be taken seriously. Remember the family in New York.

The CPSC recommends installing at least one carbon monoxide detector per household, near the sleeping area. It recommends that multi-level homes have a detector on each floor. Choose one that is Underwriters Laboratories, Inc. (UL) listed and sounds an audible alarm. Since the burning of gas does not usually require electricity, it’s best to get an alarm with a battery back up in case the power to the house is interrupted. Most quality devices cost less than $100. There are cheaper detectors that change color when a high level of CO gas is reached. Since one of the great dangers of carbon monoxide is that it can build rapidly and kill people while they sleep, non-sounding detectors would be useless in such cases.

If you’re dealing with a home built, added on to, or rewired between 1965 and 1972, aluminum wiring might be a problem for you. Research by the U.S. Consumer Safety Commission revealed that homes wired with aluminum wire manufactured before 1972 are 55 times more likely to have one or more connections reach fire hazard conditions than homes wired with copper.

Aluminum wire manufactured after 1972 was somewhat improved, though the introduction of aluminum alloys did not solve most of the connection failure problems, and aluminum use for branch wiring, that is wiring to receptacles and switches, ended by the mid seventies.

Now forbidden by building codes for internal branch wiring, aluminum wiring is still used for such applications as residential service entrance wiring, or single-purpose higher amperage circuits, including 240-volt air conditioning and electric range circuits. For these applications, a heavy-gauge aluminum wire can be used, eliminating the hazard created by the smaller-gauge branch wiring.

Aluminum wiring use started in 1965 as a cheap alternative to copper wiring. Its cheapness, observed one builder, was evidenced by the fact that no one came to a home building site to pick up aluminum wire scraps as they had always done with copper wire. Within a few years, however, the less expensive wire proved itself to be a weak substitute for copper.

One common problem with aluminum wire is that it more easily corrodes at connections than copper. Such corrosion increases resistance and this increased resistance causes overheating of the wire at connections with switches or outlets, or at splices.

Another problem arises because aluminum wiring expands more than copper during the expansion and contraction that carrying electricity causes wire to go through. The constant expansion and contraction can eventually loosen the screws holding the wire onto the light switch or receptacle, or loosen at a spice, causing the electricity to arc in the wall at the loose connection. Such an arc is like a flint rock being struck and making a spark inside the wall, eventually finding surrounding building material that will serve as tinder.

If you are not sure whether a home has aluminum branch wiring, you might be able to tell by looking at the markings on the surface of cables left exposed in unfinished basements, crawl spaces, garages or attic. Aluminum wiring will have “Al” or “Aluminum” marked every few feet along the length of the cable. Copper-coated aluminum wire does not present the fire hazard of plain aluminum wire. It is marked CU-clad or Copper-clad.

Although not all failing aluminum wire connections give any tell-tale signs of their eminent demise, there are sometimes warning signs. These include warm-to-the-touch face plates on outlets or switches, flickering lights, non-functioning circuits and the smell of burning plastic at outlets or switches.

The “feel the faces” advice, though often given, is ineffective and potentially dangerously misleading since the person doing the feeling often has no idea how much current, if any, a receptacle’s connections have been carrying, and for how long, prior to being “tested” in this way.

A better method is to turn off the power to the outlet at the main power breaker, remove the cover plate, and then, using a bright flashlight, inspect the area of each wire terminal. Look for charring or discoloration of the plastic wiring device body around the screw terminals, abnormal tarnishing or corrosion of wire and screw terminal, melting, bubbling or discoloration of the wire insulation.

Also keep in mind that such inspection can reveal only what has happened, not what might happen. An aluminum wire connection might not have overheated in the past because no significant current was ever flowing in its part of the circuit. It can look “like new” but overheat to hazardous levels when a new load, such as a television, portable heater or cooking appliance is plugged in.

If you have determined that the branch wiring in a home is aluminum, it should probably be replaced with copper wiring throughout the home and the disconnected aluminum wire left in the walls. If this is financially unrealistic, a form of patching can be done at receptacles, switches and splices. This, however, is exacting work and should be carried out only by a certified electrician. There is always risk of property damage, injury and death associated with working on the electrical system of a home. It is not a job for do-it-yourselfers. Disturbing such connections without fully knowing what you are doing can often make them more dangerous.

A practical approximation to rewiring can be achieved by a method known as “pigtailing.” This entails using a specially-selected connector and installation method to splice a short length of solid copper wire to each aluminum wire end. The copper wire “pigtail” is then connected to the switch, receptacle, circuit breaker, light fixture, etc.

In the meantime, a fire hazard can be lessened by removing from around aluminum-wired receptacles and switch boxes anything that might ignite, such as bits of wallpaper, wood dust/saw dust, insulation. Also keep stacks of storage boxes or furniture away from such receptacles.

Both ASHI (American Society of Home Inspectors) and UL (Underwriters Laboratories) have extensive information about aluminum wiring on their websites.

Strip flooring is usually referred to as hardwood flooring. Strip flooring typically is of white or red oak, maple, beech or birch; it is also often made of less expensive softwood such as hemlock, larch or elm.

Strip dimensions are measured across the face of the strip, not including its protruding tongue. Typical widths include 1-1/2 inch, two inches, 2-1/4 inches and 3-1/4 inches. A commonly used width is 3/4 of an inch.

A common problem with hardwood floors is squeaking, usually a sign that some of strips have come loose from the sub-floor. The offending strip usually can be found by walking over the floor and paying attention to the sound or “give.”

One simple remedy is to place a one or two foot length of 2×4 on several sheets of newspaper (so as to avoid marring the floor’s finish). Rap the 2×4 sharply over the loose area in a steady rectangular pattern. Avoid repeatedly hammering the block on the same spot, so as not to split the tongue-and-groove of the flooring.

Much more involved remedies include adding face nails (which you must countersink; apply putty to cover holes), strengthening the subfloor from below or injecting adhesive.

Good drainage is fundamental to a well-made and well-maintained home. A damp or standing-water filled crawl space can cause a plethora of problems for hardwood floors (see below).

Make sure water drains away from your home. Your gutters should be in good working order and should terminate several feet away from your home.

When it come to wet crawl spaces, poor drainage and subsequent seepage are not the only culprits. For example, in one home, an air conditioning duct had been left unconnected and cooled air was discharging into the crawl space, causing condensation. This, in turn, caused the home’s tongue-in-groove hardwood floor to buckle.

Here are some common problems with hardwood floors and some suggested solutions.

Cupping, also called washboard — The edges of a piece of flooring (across its width) are high; the center is lower. This generally develops gradually.

Moisture imbalance through the thickness is the only cause. Moisture is greater on the bottom of the piece than on the top. Find the source of moisture and eliminate it.

A common source is a wet basement or crawlspace. Improve drainage around the home. Dehumidify the basement or crawlspace with properly sized dehumidifiers designed for each type of space. If it’s a crawlspace, make sure it has an adequate groundcover and close off all perimeter foundation vents and consider insulating the perimeter foundation walls and heating and cooling the space with the home’s central heating and cooling system.

After the moisture has been eliminated, allow time for the floor to improve on its own. After it has stabilized, sand flat and finish.

Crowning, the opposite of cupping, the center of a piece of flooring (across its width) is high; the edges are lower. It is commonly caused by moisture introduced to the top, the finish side, of the flooring, such as wet mopping or water leaks. Often crowning develops after the effort to remove cupping, when the sanding to remove the high edges has been done too soon after the moisture problem has been solved, before the floor has been given time to flatten on its own.

To cure the crowning problem, give the floor plenty of time to stabilize on its own, then sand flat and finish.

Be aware that slight cupping or crowning is common in wood floors and should be tolerated. In many cases it is seasonal.

Buckling, tenting and ballooning floors develop when pieces of the flooring are no longer in contact with the subfloor surface.

This is generally caused by extreme moisture below the floor, resulting from a wet basement or crawlspace, added with insufficient nailing, incorrect nails or incorrect subfloor construction. It also occurs when the installer makes the mistake of leaving no space for normal expansion.

If caught early, spot repair and replacement might be possible. In many cases, however, the entire floor must be pulled up and re-laid or replaced.

Cracks, separations between individual flooring pieces, are normal. Whereas excessive moisture causes problems, dryness causes cracking. Often, if a floor has experienced cupping or crowning and then been dried out, cracking will occur. White-, light-, and pastel-finished flooring will show cracks more than darker wood-tone finished floors. Many cracks are seasonal and show up in dry months or during months when heat is used inside the home. They usually shrink, however, during humid periods.

One way to cure cracking is by introducing moisture into the home. Easy ways to do this are by boiling a pan of water, turning off the bathroom exhaust, and opening the dishwasher after the rinse cycle. Or, the homeowner can choose to live with the cracks.

Minor dents, caused by high-heel shoes or heavy objects dropped on the floor, can be fixed if the wood fibers are not broken. Cover the dent with a dampened cloth and press with an electric iron to draw fibers up.

Sheetrock cracking can sometimes be associated with Foundation settlement; however, foundation settlement is by no means the only cause. Other causes include dimension changes associated with moisture content changes and/or warping, shrinking, or dimension changes in the wood frame building structure. Moisture changes will occur frequently if the interior of a home is exposed to the atmosphere, which has varying degrees of humidity throughout the year. One very common cause of cracking is associated with moisture changes that occur following construction and remodeling efforts due to drying conditions that develop naturally inside a home especially once the central heating and air conditioning systems are utilized. These systems lower the humidity and moisture conditions inside a home. Most construction materials, including wood and gypsum sheetrock, experience post-installation drying.

The jagged, irregular cracks which sometimes form in gypsum sheetrock walls, and propagate outward from the tops, corners and sides of window and door openings, are usually caused by differential foundation settlement and/or floor sag. Cracks form in response to the racking effect induced in the wall when one side of the door or window opening drops. They tend to form at these specific locations because window or door openings create weakened sections within the walls. Cracks also tend to form in the taped joints between adjacent panels of sheetrock — another weakened wall area.

Such cracking is a common occurrence in the interior walls of older homes and is usually related to long term floor sag and/or creep. The floor structure beneath most homes consists of floor joists which span from opposite-facing foundation walls to a central main beam girder. The beam-girder usually rests upon several foundation piers. A wall which separates adjacent rooms inside a home is commonly called a “partition wall.” Walls that provide structural support to a second floor or roof are called “load-bearing walls.” Load-bearing walls must be located directly above a beam-girder and/or foundation system; thus, they are usually located near the center of a home. If these walls are not located above a beam-girder, long-term floor sag will usually occur. Partition walls, on the other hand, do not support any load or weight other than their own. Their weight, however, can be enough to make the floor sag over time. As the floor sags, one side of the doorway will drop (the door will rack), causing large stress concentrations to form in the sheetrock wall above the door opening.

Once a crack forms, unless the wall is properly stabilized with additional support, it is likely to enlarge with time, or reappear, even after cosmetic repair. This type of cracking can also be aggravated if the partition wall lines up near the center of a central beam girder. In this case, the beam-girder may also be sagging, increasing the degree of racking. Also, if differential settlements develop between the interior foundation piers and the exterior foundation walls, the cracks can worsen. Finally, one other cause of wall cracking above the interior doorways has to do with the long-term shrinkage and expansion of a center, main beam girder. This is especially true if the girder is positioned beneath the floor joists.

Differential foundation settlement problems can often be stabilized and releveled by foundation underpinning. This process entails excavating beneath the footing with closely spaced shafts and filling the shafts with concrete. Typically the concrete pour is stopped 12-18 inches below the existing footing so that hydraulic jacks can be inserted to lift and level the settled footing. Some firms utilize backhoe excavation, while others utilize augers to excavate cylindrical pier shafts. One proprietary method of repair uses helical screws to lift settled foundations. Another uses driven shafts of steel.

Floor sag problems typically require jacking and then strengthening existing joists/beams by a process called sistering, or by the construction of additional foundation pier supports beneath the sagging joist/beam members. The latter should always entail the construction of a poured-in-place concrete footing which bears on undisturbed soil, followed by the construction of a concrete or masonry pier or the insertion of a pressure-treated wood or steel post beneath the member, which has first been releveled with hydraulic jacks.

Particle board, sometime used as a less-expensive alternative to plywood, takes the wood conservation inherent in plywood manufacture a step further. Because of particle board’s tendency to absorb water and swell, however, it’s not commonly used in home-building, and should never be used as a structural element. Just as the name implies, particle board is created by taking particles of wood (saw dust), gluing them together, and forming a uniform slab of material.

Plywood is made by pressing sheets of wood together so the grain in each sheet is perpendicular to the grain in the sheet above and below it. Before lumber makers began producing plywood and particleboard, planks of solid wood were used as sub-flooring and exterior wall sheathing (the later provides shear strength, which keeps the house from racking side to side). Particle board is cheaper to produce than laminated plywood, hence its popularity with some home-builders and mobile home manufacturers.

Unlike solid wood, however, which rots and becomes useless only after an extended exposure to water, particle board often is held together by water-soluble resin; so, once it gets wet, it swells and disintegrates.

Particle board is used when a smooth surface is more important than strength. For example, less-expensive kitchen cabinets are often made of particle board (underneath an oak or cherry veneer), as are many enclosures for electronic equipment, such as televisions. Countertops are often made of particle board beneath Formica or some other water-resistant material. Consequently, if the water-proof material gets a crack or a hole in it, water will find its way to the particle board and make it swell.

Assemble-it-yourself furniture is often made of particle board. Extended length surfaces of such furniture, such as shelves and desk tops, easily and quickly develop deflection, or sag, because particle board has no grain. It is particularly unwise to use particle board in construction of bathrooms and kitchens. If water spills from the tub or sink and finds its way to the edge of the vinyl or linoleum covering, it will get to the particle board and cause it to swell.

If particle board is used as a floor underlayment and gets wet, ripples or humps will appear in the floor. The damaging water doesn’t have to come from a catastrophic source, such as a water leak or a bathtub overflow. If the crawl space of a home is damp, water vapor can rise in the particle board and cause ripples.

Despite its drawbacks, some home-builders use particle board as a floor underlayment. Some of its advantages are that it provides a smooth, uniformly thick, solid base (free of knots, voids or grain) and adhesives spread easily and evenly over the smooth panel surfaces. Particle board panels are made to resist impact or denting. The panels are easy to cut with ordinary hand and power tools. Most building codes approve particle board as a floor underlayment.

The subfloor on which it is applied must be of wood construction, dry, level, securely nailed and free of all foreign matter and projections. Ground level in basementless spaces should be at least 18 inches below the bottom of the floor joists.

Never apply particle board underlayment over concrete or below grade.

A vapor barrier with a maximum rating of 1.0 perm should be used over board subfloors and as a ground cover in all basementless spaces.

Start laying the panels at a corner of the room. Leave a 3/8-inch gap between underlayment and walls. Arrange panels such that four panel corners do not meet at any one point. Butt panel edges and ends to a light contact.

Does the potential exist for contaminated water to mix with your drinking water? The answer is–probably “yes”, especially if you have an older home. Houses built during the first part of the 20th century are the most likely to have such a potential problem, but amateur plumbing practices and other plumbing nightmares still create the potential for public water contamination in many of the homes we inspect.

What are commonly called “cross-connections” occur whenever a potable water source comes into direct contact or “connection” with a holding basin that contains contaminated water, i.e. a kitchen sink or bathtub. Blatant cross-connections are thankfully prohibited by most Plumbing Codes. Where there is no other reasonable alternative, however, cross-connections to the potable plumbing system are allowed if an approved protective device is used. These are called “back-flow preventers”.

The process by which a contaminant enters the drinking water plumbing system is called back-flow. Back-siphonage or negative pressure can cause back-flow. Negative pressure can be caused when the pressure in a customer’s water system is increased above that of the city’s or county’s water supply system. This can happen, for instance, when a customer uses a pump to increase his water pressure and it malfunctions. “Even heating water, which expands the water and produces pressure, can create back pressure”, said David Kellogg, president of the Tennessee Chapter of the American Back-flow Prevention Association.

“By far the major condition that causes back-flow in the average home would be back-siphonage,” according to Kenny Hart, a home inspector in Virginia Beach, VA., writing in the April, 2000 issue of the American Society of Home Inspectors (ASHI) publication, The ASHI Reporter. Back-siphonage back-flow begins when the normal flow of liquid is reversed by the introduction of a vacuum or partial vacuum. Siphoning gasoline from a car’s gas tank is a good example of how back-siphonage back-flow works. Once the vacuum is introduced by someone sucking on the hose, the gasoline will flow out of the tank without continued sucking on the hose. A water main break, during which the water flows in a direction different from its usual course, or a fire engine pulling water from a fire hydrant can begin the back-siphonage back-flow process. Although this alone won’t contaminate the public water supply, it may if someone has an active cross-connection inside their home.

The most common cross-connection that we see during a home inspection is when a faucet (spigot) is lower than the overflow drain in a sink, bathtub or laundry basin. Hence, if a negative pressure developed in the water main (during a fire or break) and the sink/tub/basin was full of contaminated water, and the spigot was open, the contaminated water could be sucked back into the potable water supply. This potential problem also exists with kitchen sink vegetable sprayers and hand-held shower heads such as shower massagers, if the tube is long enough for the sprayer head to drop into bath or sink water.

Decatur plumber Eric Hepler said he rarely sees dangerous cross-connections in homes anymore, except on some old-fashioned bathtubs and toilets, or some do-it-yourself plumbing creations. It’s not a problem with modern, code-legal fixtures, he said, which are designed to prevent back-flow.

Another potentially dangerous cross-connection is an older toilet ball cock that has its shut-off point below the water level in the holding tank. These critical cross-connections are rapidly disappearing since these types of toilet ball cocks are no longer manufactured.

Historically, the most common cause of widespread community water supply contamination has come from unprotected hose bibbs or sill cocks. It is not unusual for home owners and service personnel to attach a garden hose to a hose bibb, drop the hose into a large tank filled with chemicals or fertilizers then walk away. There have been several deaths and multiple illnesses attributed to this scenario-here in Alabama. Protection against such occurrences, as a 1981 mishap in which the contents of a tank filled with insecticide got pulled into a city water system, is available in the form of a ten-dollar “hose bibb vacuum breaker.” Kellogg said such incidents are a growing problem because of the spread of toxic substances in everyday use.

Another potential problem is a sprinkler system. Since these are directly attached to the potable water supply, some form of back-flow prevention device must be installed to prevent possible back-siphonage. Many sprinkler systems are installed by “do-it-yourselfers” and these are the ones unlikely to contain a back-flow device or check-valve.

As you can see, cross-connections are a serious health/safety concern and one that all home inspectors should be looking for. You might want to discuss this concern with the next home inspector you meet. Should the inspector be unaware of this problem or shrug it off as unimportant, I’d recommend seeking another home inspector next time around.

For more information about cross-connections and their potential dangers, Watts Regulator Company of Andover, Massachusetts (www.wattsreg.com) offers a booklet entitled 50 Cross-Connection Questions, Answers & Illustrations. Or contact David Kellogg at Gallatin (TN) Public Utilities.

A standard home inspection does not include air quality testing. Most home inspectors do not have the sophisticated and expensive equipment needed to test air. Moreover, with every added service, there comes increased liability, so providing air quality inspection services naturally increases the inspector’s risk (of being sued). Nevertheless, you may find clients who want indoor air quality testing. The following information is provided to help you understand and deal with these “very serious and legitimate requests.”

Incidents of indoor air pollution have increased lately due to our “air-tight” modern construction practices. What was once perceived as an energy saving feature has now revealed its ugly side-lack of air infiltration results in the recirculation of the same old air, causing increased pollution concentrations inside the home. Polluted indoor air at home and at work has been blamed for increasing cases of respiratory ailments, from asthma to allergies. Even such complaints as chronic fatigue, often dismissed as psychological, are possibly the product of unhealthy air.

A human breathes about 50 gallons of air every day. Air is invisible because the molecules that comprise it are too small to reflect light. We “see” air only when it carries airborne particles, since even the smallest suspended particles, such as those that make up cigarette smoke, are thousands of times bigger than the nitrogen, oxygen, carbon dioxide and water vapor molecules that make up air.

There are thousands of possible pollutants: formaldehyde from carpets, drapes and particle board; asbestos lurking in most homes older than 20 years–tucked away in pipe insulation, acoustical materials and floor tiles; and the most common source: molds and mildew.

Molds and mildew are fungi that can grow on a surface containing any amount of organic material, which includes almost all building materials. Though some fungi, such as mildew, do no direct damage to building materials, their presence is an indication of a high moisture condition that can nurture other fungi, including wood rot. In humans, allergy is the most common symptom associated with exposure to elevated levels of fungi since most fungi produce antigenic proteins that can trigger allergic reaction in allergy-sensitive people. Molds also give off spores, which, combined with other common household particles such as pollens and pet dander, settle out as dust.

Molds grow at temperatures above 40° and below 100°. They do not need the presence of standing water. High relative humidity or the build up of moisture on building surfaces will do. The danger of mold growth is greatest on building materials that have gotten wet, since most have the tendency to absorb and retain moisture. Water leaks that have been present long enough to wet surrounding materials provide productive spawning grounds for molds and their spores. Another hot bed for mold is the sub-flooring above a damp crawl space. A polyurethane moisture barrier should cover the entire ground surface and fresh air should circulate freely throughout the crawl space.

Keep rooms clean and dry. Good ventilation is vital to keep mold colonies from flourishing. Pay special attention to bathrooms, kitchens, basements and crawl spaces, areas that are normally exposed to high humidity. Clean any moldy surface with a disinfectant, such as chlorine bleach. If any furniture or carpet gets wet, it must be dried thoroughly or discarded. Humidifiers, dehumdifiers, and air conditioning condensing units can promote mold growth and spore-filled air. They should be cleaned regularly with a disinfectant.

Central heat and air units can work against a clean indoor environment by circulating the same contaminated air throughout the home plus pulling dust from the ducts into the home. Make sure all filters are changed regularly and often. It’s a good idea to have your ducts professionally cleaned. Such cleaning employs a 200 psi (pounds per square inch) jet nozzle that shoots air into one end of the duct while a powerful vacuum pulls on the other end. The push-pull method is fairly standard among duct cleaners. Some offer brshing and post vacuum sanitization. The cost depends on the size of the home, and is usually priced per vent-prices range from about $20 to $50 per vent for the works.

Dust Mites

Another effect of household dust is that it serves as home for dust mites, microscopic, eight-legged creatures who live in dust. When dust becomes airborne the mites spread and form new colonies. They live on mold spores and human skin scales. They are generally found on fabric, such as sheets and furniture coverings, duct work, and mattresses. Most mattresses are crawling with dust mites.

They play havoc with someone’s respiratory system. Someone with a weak immune system or allergy-sensitive breathing can develop asthma from inhaling and ingesting dust mites. There’s no shortage of food for them. Humans shed about one gram of skin per day, about the weight of a penny every three days. An old mattress could have over a pound of gray dust made up mostly of human skin scales. If you notice you tend to cough after you climb into bed, you might suspect dust mites. Plastic dust mite covers are available for mattresses

Carpets that are infested should be removed. Repeated washing can increase the levels of mold and mites. Covering instead of chemicals is recommended for dust mite infestations because the protein that triggers allergic reactions is in the mite’s skin, so the inhaled mite does its damage, living or dead. And spraying pesticides inside your home deteriorates the air quality even further. But if you must wage chemical warfare, Acarosan is sold for dust mite elimination, but it’s not labeled for use on bedding.

Since dust mites are so widespread and might seem overwhelming, many people choose to ignore them. But if asthma attacks are increasing in your home, you should consider doing something about household mold, dust and mites. Wash sheets in very hot water. Heat and dryness are hostile to mites.

More Information

We called Huntsville area environmental testing companies and duct cleaners but found none who test for residential dust mites. Mid-South Testing in Decatur, however, conducts such tests. You can get do-it-yourself test kits from your local Cooperative Extension Service office. There are several web sites that address sick house syndrome-the best of which is probably a New England home inspector (Jeffery May) who specializes in air quality testing. His personal views of indoor air pollution can be reviewed at www.jmhi.com

There’s no question that brick veneer is probably the most popular siding material used in median to upper scale residential construction in North Alabama. Therefore it’s no wonder that so many brick veneer problems pop up during residential home inspections.

Part I. Leaks in Brick Veneer

Contrary to popular opinion, brick veneer is not waterproof. In fact, it can leak during periods of heave rain, especially if the individual brick units are laid in weak (poor quality mortar mix) and sloppy (porous) mortar joints. The leakage occurs through cracks and separations and open gaps/holes in the mortar or through cracks in the brick not necessarily through the clay-fired brick masonry units, themselves. Thus, the use of a properly blended (high quality) mortar mix and full-head and bed (completely filled) mortar joints is mandatory for water tight brick veneer construction.

In spite of using quality mortar and full head/bed joints, water leaks may eventually occur due to cracking in the brick or mortar. In other words, very fine cracks will almost surely develop in any brick veneer due to a variety of causes, including normal weathering. These cracks are typically too small for us to see so we’re often oblivious to their presence. Because of this cracking tendency, the major building codes (throughout the country) all require the use of proper flashing details above windows/doors and at the base of walls, with proper water-proofing measures between the brick veneer and the wood-frame building structure. The latter is best accomplished by covering the wood-frame building with an air/moisture barrier (like Tyvek) then tucking plastic flashing beneath this barrier and out through the brick — through a single, horizontal, mortar joint which is usually located at the steel lintel supports above windows/dooors and somewhere just below the top of the foundation wall. The vertical joints between the brick, called head joints, directly above this tucked-in flashing, are left open at some close, uniform spacing, to allow the penetrating water to seep back outside the brick veneer wall. These open joints are called “weep holes”.

For more information about weep holes and the use of proper flashing details above windows/doors (at steel lintels) and at the base of the foundation, you can contact the Brick Industry Association at (703) 620-0010 and request a copy of their Technical Notes numbers 7, 7A – 7D & 7F; or visit their web site at www.bia.org and order on line. I’ve provided a direct link to the BIA on our web site (go to the links page).

Part II–Sagging Garage Door Steel Lintel Beams

Perhaps the most common brick veneer cracks in residential construction, other than those cracks associated with differential foundation settlements and brick expansion, are the ones that form above double-wide, garage door openings. This is my personal observation (based on more than 25 years of residential inspection experience) and may not be an accurate or factual statement. Nevertheless, it is my opinion/contention that crack formations in brick veneer above/beside double-wide garage door openings are the rule rather than the exception. I’ve seen hundreds of them!

In order to understand the causes of these cracks, one needs to understand the way in which brick veneer is constructed above such wide openings. In most cases, the brick veneer located directly above the opening is supported by a structural steel angle (beam) which in turn rests on the side wall sections of brick veneer (abutting each side of the door opening). These steel angles are commonly called “lintels or steel lintels” and generally have an outstanding leg which measures about 2-1/2 or 3-1/2 inches wide. Note that this width conforms to the typical brick masonry units which are used in residential construction; i.e. they range from 2-1/2 to 3-1/3 inches wide.

The general construction procedure is to lay-up the brick veneer, along each side of the garage door opening, until both sides reach the tops of the door jambs. At this point, the brick masons stop laying brick and the newly-laid brick veneer wall is allowed to harden or cure. After a day or two, a steel angle beam or “lintel” is laid across the top of the garage door opening the ends of the beam resting directly on the two brick veneer walls which directly abut the sides of the garage door frame. Once the lintel beam is in place, the masons continue laying the brick veneer, up and over the steel lintel, eventually embedding the lintel and hiding it from view.

The size (thickness and cross-sectional dimensions) of steel angle needed to span across the door opening and adequately support the brick above is based on the weight of the brick above the opening. In other words, the taller the brick veneer wall above the opening, the more the brick weight. For very tall heights of brick veneer, however, which exceed the height of an imaginary equilateral triangular who’s apex is created or formed by two sides oriented 45 degrees to the base (lintel), the total weight applied to the lintel is assumed to be the weight of the brick veneer located inside this triangle. The brick overlying and/or outside this triangle is assumed to arch or span across/over the opening. For a 16 foot wide opening, the apex of an equilateral triangle is 8 feet tall!

A normal rule of thumb for determining the weight of brick veneer is to assume that it weighs about 30 pounds per square foot of “face area”. Hence, a one foot wide strip of brick veneer wall, eight feet tall, weighs about 240 pounds. As such, an 8-foot tall brick veneer wall exerts 240 pounds per linear (lineal) foot on the supporting foundation/footing/lintel/etc. Fortunately, in most residential cases, the height of brick veneer above the garage door (steel lintel) is usually only about two to three feet tall. In these cases, the weight of brick supported by the lintel is equal to a uniform load of roughly 60 to 90 pounds per linear foot (30 psf x2 ft or 30psf x3ft).

In spite of this apparently small weight, however, I can tell you that there are no readily available steel angle sections (that a local builder can purchase from a steel fabricator) that can span 16 to 18 feet, support its own weight plus that of 2 to 3 feet of brick veneer, and not deflect, twist or bend excessively. And here is the rub. Excessive deflection is defined as the lesser of 0.3 inches or L/600 inches, where L is equal to the lintel span in inches. For a 16 foot lintel, L/600 is equal to 16×12/600 which equals 0.32 inches. That’s roughly 1/3 of an inch (between 1/4 and 3/8 of an inch). This rigid deflection limit has been set by the Brick Industry Association (BIA) — formerly the Brick Institute of America (refer to their Technical Note #31B). The Standard Building Code (which governs construction in Alabama) recognizes and references the recommendations of BIA. The purpose of the deflection limit is to improve/ensure the long term serviceability of brick. It is not to imply that whenever larger deflections occur in practice, there is some “implied” major structural problem or concern. The deflection limits simply reflect the fact that brick veneer is a hard, rigid and “brittle” material which cannot take (endure) very much distortion without cracking. Hence, to avoid cracking (which leads to more problems, such as leakage), the BIA has placed rigid deflection limits on any lintel beam used to support brick.

This means that whenever we see steel angles being used to span across wide openings, like double car (wide) garage doors, they are hopefully bolted or secured to some type of back-up structural member that helps provide the added strength (rigidity) necessary to prevent excessive deflection/twisting, and therefore brick veneer cracking. And this “hope” brings me back to the basis of this article….I contend that if one were to drive throughout North Alabama, and measure the deflections of the steel angle lintels being used to support the weight of brick veneer extending above double-wide garage door openings, the measured deflections will typically exceed 3/8 of an inch. I further contend that in those cases where the deflections are about 3/4 of an inch or larger, you’ll find brick veneer cracks somewhere above the lintel. Conversely, in those cases where the deflections are ½ of an inch or less, I bet you won’t find cracks at least cracks due to deflection.

If my predictions prove true, I hope you’ll admit that there is a serious problem in our local home building industry. In other words, excessive deflection would imply that the steel angle lintels are not being connected to or reinforced by structural back-up units/members. As such, there appears to be a serious “lack of knowledge” amongst the local home building trades (and obviously the Code enforcement agencies) regarding the limitations of steel angle lintel beams. Otherwise, there’s an ongoing blatant disregard for proper lintel beam installation in our local residential construction. Please discuss this topic with your builder friends. Encourage them to contact the Brick Industry Association at (703) 620-0010 and request a copy of Tech Note 31B.

If wood rot has occurred, it will require repair.

A common source of wood rot for floor structures is a damp, ventilated crawl space. Building Codes have long required that a crawl space should have foundation vents within three feet of each major building corner and every ten feet between these corners. An intact, plastic vapor barrier should cover the ground beneath the house. Water can seep under or through the foundation walls into the crawl space. So, adequate drainage around the outside of these walls is very important to keep the ground from becoming saturated. Another source of moisture can be an air conditioning condensate drainage pipe that incorrectly drains water into the crawl space. It should be made to drain outside the home.

Water in the crawl space can promote the growth of mold, mildew, and fungi that actually eats and weakens the wood of the floor substructure. Wood is a hygroscopic material so it readily absorbs water vapor. Wood absorbs water slowly, and it can take a considerable amount of time before dry wood can absorb enough moisture to be in danger of decay.

A particularly dangerous source of water in the crawl space is any kind of hot water leak. Steam seems to promote rapid bacterial and fungal growth.

Mold and mildew belong to a large botanical classification known as fungi. Mildew is a black fungus that grows on the surface of wood and darkens it over time. Although it doesn’t cause damage, it is a tale-tell sign of a high moisture condition. Mold and mildew often grow on surfaces when the relative humidity (RH) near the surface is above 50 per cent.

Decay organisms are also fungi, but they typically take longer to get started than mold or mildew. Decay fungi can attack wood and other materials when the moisture content(m.c.) is above 20 percent. The percentage of RH is different from the percentage of m.c. In most homes the m.c of the building material is considerably less then the RH of the air surrounding it. The m.c. of wood is expressed as a percentage of the wood’s oven-dried weight.

A living tree contains a certain amount of water. For example, the m.c. of a birch tree might be 75 percent. By the time the lumber from the tree reaches consumers the wood has usually dried to about 19 percent m.c (15 percent for kiln-dried products.) The wood in a home continues to lose moisture over time until it reaches equilibrium with the climate it is in; the m.c. of wood in most homes is typically less than 10 per cent.

Decay problems occur when wood remains wet for an extended period. For example, if there is a plumbing leak under a bathtub the floor can be wet for many months. Remember that wood absorbs moisture easily, but slowly. If there is enough moisture present for a long enough period of time, the m.c. of the wood can rise above 20 per cent and decay is a strong possibility. If a leak is temporary, the wood won’t be wet long enough for decay organisms to attack it.

The best way to cure a moist/humid crawl space is to close off the foundation vents, cover the ground surface with a seamless vapor barrier, attach the vapor barrier to the perimeter foundation walls and interior piers, then insulate the perimeter foundation walls and heat and cool the crawl space using the home’s central heating and cooling system. When this is not possible, you can place a specialty dehumidifier in the crawl space — one designed for this specific application, and be sure to direct the collected condensate outdoors.

A fireplace adds warmth to any home. Whether lying before a quiet romantic blaze or huddling near a roaring conflagration, humans have made fireplaces part of home designs since it was first figured out that being warm was better than being cold.

That fact hasn’t changed over the years. Neither has fireplace making. It still involves stacking blocks or bricks in a way that will allow fuel to be burned efficiently, heat to be conducted into the room, and smoke to be ushered up the chimney. And this is important, too: that stack of bricks, usually weighing ten or more tons for even a modest chimney, has to stand up straight.

So you’re out eyeballing the old home place. You admire the straight lines of your home. Lack of sag is usually a good thing. But something is amiss. You take a closer look. It’s your chimney! It’s…leaning! Get a grip. Calm down and feel the firm earth under your feet. Wait a minute! Maybe that’s the problem. How firm is the earth under your feet?

Leaning chimneys are usually caused by settlement or bearing soil failure. It doesn’t take much. For example, if the outer edge of your chimney’s footing sinks just 1/4 of an inch, the resulting crack between the chimney and the roof can be as much as two to three inches! Tiny slip at bottom equals huge gap at top. Through that gap can come all sorts of trouble. And that trouble is usually in the form of water.

The sandy silty clay soils often found in Alabama normally provide a firm foundation and usually stay put. It’s when the footing is placed on soil that has been “disturbed” during construction, or, worse yet, soil that has been contaminated by building debris or other foreign matter, that the problems often begin.

Even such susceptible soil, though, usually needs a reason to move. And that reason is usually in the form of water.

While you’re trying to figure out why your chimney is out of plumb, take a look at how water drains around your little piece of paradise. Is water moved away from your house? Do your gutters keep it away from the foundation of your chimney? Highly plastic clay soils can shrink or swell due to changing moisture conditions. Winter rains usually mean swollen soil. Summer soil is comparatively dry, or desiccated.

Such movement, as natural as it is, is detrimental to masonry structures and provides an opportunity for the chimney to rock back and forth and separate from the home. Usually this is nothing to worry about if the chimney footing bears deep into the ground.

Exaggerate this motion by poor drainage, however, and you’ve got a problem. Make sure water drains away from your house. Make sure that runoff from the roof does not saturate the ground around your foundation.

And before you exclaim that your chimney’s lean is due to nothing so mundane as water drainage (Thank you!), consider that the more exotic reasons, such as wind and lightning, rarely ever turn out to be the true cause. That is unless you’ve just come through a horrific storm. Even then, it was probably the copious rain and not the abundant breeze that made your chimney totter.

If lightening had struck your pile of bricks, there would likely be an explosive type of damage rather than an outward lean.

Wind? Probably not. If wind caused your chimney to lean, it would have to have been some fantastic and memorable wind, as in “You remember the wind of ’95. Put the part on a different side of my hair. Blew my chimney crooked, too.”

Not likely. Note that chimneys usually have only small areas subjected to the wind. Most of the structure is protected by the house and roof. The force of wind is usually negligible compared with the weight of the chimney.

So the gap between your chimney and your house continues to let water ravage your roof, your floor, your walls. You know water. And on top of that, your chimney might go ahead and fall on over. What can you do?

Call a professional. The inspectors at JADE Engineering will be happy to visit your less-than-perpendicular pile of bricks and tell you if the problem is worth fixing. A JADE engineer will even arrange a soil test to reveal just what kind of dirt you’re dealing with. If the underlying soil is an expansive clay or pile of rubble — as in former dump — then an appropriate repair can be developed.

Keep in mind, though, that trying to straighten a leaning chimney is not a do-it-yourself proposition. Your JADE engineer will be able to recommend people who are experts at this complicated and exacting task.

Here’s one way a professional might go about straightening your chimney. Vertical shafts are drilled several feet deep along the edge of the chimney’s foundation. These are then filled with reinforced concrete. The pour is stopped about 12 inches beneath the footing bottom and the concrete allowed to cure. The solid concrete pier can then become a surface for jacking the original chimney footing back to level. Once the footing is level, or plumb, then the remaining space between the original footing and the pier cap can be filled with concrete.

Once your chimney is level, you can then repair the displaced roof flashing. Remember: seeping water is never idle.

If the inspection reveals that your chimney is too far gone, then you can dismantle it and rebuild. This time make sure the footing is made competent by being big enough to spread the massive weight of the chimney over a large enough area. And make sure you have dug deep enough to reach undisturbed soil that will bear your chimney’s weight over the long haul.

The effect of hailstone impact on roofing materials has been studied by several different authorities, including the U.S. Department of Commerce. Their findings, published in a paper entitled, “Hail Resistance of Roofing Products,” indicates that damage to shingle roofing should not be defined as cosmetic surface indentations. Only actual fractures in the surface coating or base material should be defined as damage. Superficial scuffing does not interfere with the performance of the roofing product. The Commerce Department’s tests further revealed that fiberglass-asphalt shingles, as opposed to the older organic-mat shingles, have excellent resistance to hailstone impact — at least for hailstone less than or equal to two inches in diameter. The reason is that the fiberglass mat provides greater tensile strength and toughness inside the shingle.

The amount of hail damage suffered by a roof depends on its age and on the type shingle used. The older and weaker organic felt-based shingles are known to undergo rapid natural deterioration from ultraviolet radiation exposure. The deterioration is usually manifested as cupping or curling of the individual shingle and/or extreme loss of granular surface material. When hailstones strike the surfaces of these older, brittle materials, they can actually break through the shingle. This leads to a rapid degeneration and material breakdown, increasing the chance for leakage.

Small indentations on shingles, therefore, are not considered damage, if the fiberglass base mat is not fractured. Breaks in the base mat will allow leaks, while surface dents and dings will not affect the shingle’s ability to repel water.

Hailstones with diameters of 1-1/2 inch or more are usually required to break shingles or knock holes in them.

Accompanying high winds can damage roofs by blowing off deteriorated or loose shingles, and cause other problems as well.

A common problem with assessing wind damage is that strong wind is often blamed for damage to a home that existed before the wind, but was never noticed until a storm or the close proximity of a tornado prompted scrutiny.

Besides knowing that a direct hit by a tornado will shatter and scatter almost any building, or that direct hits by tornado-launched debris can inflict much damage, most people know little about any other effect a tornado can have.

Research conducted by the University of Chicago, The National Weather Service, the Institute of Disaster Research, and others has established common rules about tornadoes and dismissed some of the myths, such as atmospheric over pressure damages to residential buildings, with the book most often cited being, Tornado: An Engineered Oriented Perspective. This book describes tornado damages as always increasing from the “outside in” and the “top down.” Residential buildings invariably suffer much worse exterior damages than interior damages and invariably these damages are also worse on the upper levels. The primary destructive components of a tornado are wind pressure and flying debris. Therefore, a tornado is likely to damage the roofing and exterior siding of a building prior to causing damage to the interior or foundation structure. Hence, unless exterior damages are significant, the likelihood of interior damages are very small.

Yet, many people insist that a passing tornado “twisted” their home, or lifted it off the foundation and set it back down, causing damage.

This discovered damage is often the result of years of poor maintenance, noticed only after a tornado has passed.

EIFS (exterior insulation finish system), often called Dry-vit, coats a home or office building with a hard, rigid covering that can be applied to a flat surface of any shape. Available in hundreds of colors and several textures, EIFS is a versatile alternative to brick veneer or vinyl siding. Its use in construction allows an architect to employ design shapes and angles that would be impractical if stone, brick or other conventional siding were used. EIFS is also less expensive to install than many conventional exteriors. And, it can provide the most thermally efficient exterior wall covering available.

When properly installed, EIFS can provide an attractive protective shell for the building’s substrate, be it wood or metal. If manufacturer’s installation guidelines are not strictly followed, however, EIFS can develop cracks and leaks that allow water to get behind the textured facing and damage the substructure. Water intrusion behind the EIFS is its most common problem.

Proper installation is critical around doors and windows, with the EIFS stopped about 3/8-1/2 inch from the door or window frame and an expansion joint placed there. The joint should consist of a closed cell back-up rod and flexible sealant at least 3/4-inch deep.

Moisture intrusion can also take place where the EIFS intersects horizontal and vertical surfaces. According to the manufacturers, the EIFS system should be held no closer than two inches from the top surface of the roofing shingles. This prevents roof-shed moisture from contacting the bottom surface of the EIFS and rising up through it. At any point where the system terminates against a dissimilar material, such as siding or masonry, a minimum 3/4-inch gap must be left for an expansion joint and caulking.

The most common type of Exterior Insulation and Finish System (EIFS), sometimes referred to as synthetic stucco, typically consists of five components: adhesive, insulation board (attached to substrate with the adhesive), a base coat into which a fiberglass mesh is imbedded, and a decorative finish coat in the desired color. This type system, called a face sealed barrier EIFS, resists water penetration at its outer surface. It is not intended to drain water from behind, however, and in this way it differs from some other types of cladding that have a weather resistant barrier behind the cladding and may have air spaces between the cladding and substrate.

The base and finish coat known as the Lamina, is quite water-proof, so, once moisture intrudes behind the lamina, there is no where for it to go. Such water intrusion in wood-framed, EIFS-clad houses has become a major issue to EIFS makers, applicators, home builders, code officials, real estate agents, homeowners and home buyers.

The EIFS marketplace suffers from an abundance of inadequate and misleading information, according to the NAHB (National Association of Home Builders), which conducts EIFS Remediation Seminars to demonstrate when and how EIFS and substructure repairs should be made. One of the most common myths about EIFS is that any water intrusion requires complete removal of the cladding.

Good EIFS maintenance starts with regular visual inspections, preferably two per year. Even when properly installed, sealant areas require periodic inspection and maintenance. The effective life span of sealant varies greatly, depending on environmental conditions, sealant type and installation. It might be as short as three years under severe conditions. Under more typical conditions, the sealant might not need replaced until after 8-10 years. Check for missing, damaged, or deteriorated sealant between the EIFS cladding and windows, doors, and around electrical fixtures, electric meter bases, hose bibs, refrigerant lines and vents — any opening in the lamina.

Only polyurethane or silicone sealant meeting the ASTM C920 Standard Specification for Elastomeric Joint Sealant should be used. Any replacement sealant should be of the same type that was originally used. Polyurethane sealant, for example, should not be used to replace silicone sealant because polyurethane does not bond well to surfaces contaminated with silicone. However, silicone can be used to replace polyurethane, so silicone is a safe choice if you do not know which kind was originally used. Inspection of the lamina might reveal cracks, holes, and discoloration, requiring the services of a qualified EIFS installer or repairer. Staining might also occur, often from soil back-splash or from sprinkler over-spray or from mildew and mold. Proper installation of EIFS requires that it be terminated at least eight inches above grade. Avoid bare earth near the structure, and remove any vegetation that might prevent the lamina from drying after a rainstorm.

Stains and mildew are not usually associated with moisture intrusion and can be washed off. Consult the manufacturer of your system to get their specific cleaning recommendations. Dry-vit, for example, recommends a solution of 1 gallon of water, 1 quart of bleach and 1 cup of trisodium phosphate. Before you clean, make sure the surface is in good shape and there is no missing sealant (to avoid introducing moisture behind the cladding.) Since the finish coat of many EIF Systems is noncementitious, washing should be done as quickly as possible to avoid softening the finish coat. The finish coat can be damaged by harsh chemicals, strong cleaners, many solvents and extremely hot water. A mild liquid detergent is typically safe to use with a soft-bristled brush. Do not use wire brushes or other abrasive tools.

Damage can be significant if moisture intrusion goes undetected. Inspection of an EIFS-clad building by an engineer or other qualified professional should be routine. The location of water entry is often difficult to see, and any damage to the substrate and structural members behind the exterior often cannot be detected by visual inspection. Inspections should be done annually, using both a non-invasive moisture meter and a probe-type meter that penetrates the lamina. Such meters are usually the only way to detect moisture behind the lamina.

For more information concerning EIFS damage and repair, contact the NAHB Research Center’s HomeBase Hotline, at 800-898-2842, or their website at www.nahbrc.org.

Remember that even EIFS installed scrupulously, following manufacturer’s guidelines, can develop problems. Conversely, EIFS that was not installed to the letter of the guidelines can, with proper maintenance, provide satisfactory service.

There are two primary roof framing systems used by local home-builders: rafters and trusses, as well as two primary roof shapes: gables and hips.

Rafter-framed roofs consist of individual rafters (sawn lumber members), usually spaced from 12 to 24 inches on center, which span from the exterior walls or roof-eaves up to the roof top or ridge, or into the sides of the main hip rafters. This style of roof construction is often called “stick-framing”. The most common rafter size is a 2×6; unfortunately, this small-size member cannot span very far and must typically be braced near mid-span. A structural analysis will usually show that the roof-bracing system picks up most of the roof load (weight). Hence, it is very important that the roof braces land (rest) on only designated interior “load-bearing” walls. Unfortunately, it appears as though many builders/framers do not realize this since they often support the roof bracing systems on the closest or most convenient interior room partition wall. This can lead to long-term floor sag because most floor joists are not sized for roof loads.

The ridge board located along the peak of the roof typically does not provide any structural support for a rafter-framed roof system; it simply serves as a convenient bearing-plate or nailing plate for the opposing rafters. However, it is important (and a Code requirement) that the ridge board be deep (tall) enough to provide full contact to the cut face of the mating rafter and that opposing rafters meeting at the ridge directly align with one another. Whenever the ridge board is non-structural, it is absolutely necessary that the roof rafters be lapped alongside and connected to the underlying ceiling joists at the exterior wall plate; moreover, the ceiling joists that extend across the home must be properly lapped and connected to one another because they provide a critical “tension-tie” across the home. If the ceiling joists do not provide this critical tie or if they span transverse to the roof rafters (which is often the case), the roof ridge will likely sag and the exterior walls will likely lean outward.

The latter is a common problem with stick-framed cathedral roofs/ceilings. In this type of roof system, the rafters and roof decking also serve as the interior ceiling. Since a conventional rafter-framed roof exerts outward forces on the supporting exterior walls, a structural ridge beam (board) is required for cathedral ceiling construction because there are no ceiling joists to provide the normal cross-tie. In other words, if the ridge beam is capable of providing vertical support to the rafters, then they do not exert an outward thrust on the supporting exterior walls. A structural ridge beam normally consists of either glue-laminated timber (glu-lam), laminated veneer lumber (LVL) or structural steel. Seldom will a solid-sawn lumber beam or built-up lumber beam suffice-especially for long ridge beam spans.

Failure to provide a structural ridge beam in cathedral ceiling construction always results in roof sag and corresponding outward lean in the exterior walls which support the rafters. Although I have never witnessed the collapse of an improperly constructed cathedral ceiling, I suspect that it can happen. The reason why complete failures don’t occur is probably because the distortions that slowly develop inside the home, from leaning walls and sagging roofs, gives the homeowner plenty of time to hire a professional to develop a corrective repair. Hence, this condition should never be ignored, no matter how slight the distortions.

Roof Trusses

Truss-framed roofs consist of pre-engineered, light-gage-metal-plate-connected sawn lumber members which are fabricated inside a controlled environment, per some proprietary engineering design and delivered to a construction site on flat bed trucks or special “cradle trailers.” These structural units/frames are designed to withstand numerous Code-specified structural load combinations and, because of their engineering and close fabrication tolerances, often provide the best solution to complex roof shapes or difficult roof framing configurations. Trusses usually transfer all of their load to the outer bearing points (exterior walls); because of this, they do not need any support from interior room partition walls. Because roof trusses are designed to span across the entire width of a home, the top chord of the truss and oftentimes many of the interior web members are placed into compression. The compressive forces try to make the truss members buckle or distort out of plane and, unless they are properly braced and held straight during erection, the entire truss may warp and distort. This can lead to reduced load-capacity, increased deflection, and the possible transfer of roof load to interior room partition walls. Once the roof decking is nailed to the truss assembly, the top chords become permanently braced. The very long compression web members (interior diagonal members between the top and bottom chords) still require some sort of permanent bracing to prevent them from distorting. Many home builders and framers do not realize this. Another problem with trusses is that very long/large trusses are usually flimsy and somewhat fragile and hard to handle at the job site. Unless the trusses are handled and stored very carefully in the field, and later during actual erection, the metal-plate connections may detach from the wood members. If this occurs, the truss has been compromised and will no longer behave as designed unless repaired properly/immediately. Also, if any truss member(s) are cut or damaged during construction or later by other trades (electricians, plumbers, HVAC), the truss will be compromised and rendered somewhat ineffective. In either case, the end result is usually roof distortion, ceiling distortion or the creation of isolated floor sag.

It is nearly impossible to prevent cracks from developing in concrete slabs on grade, especially exterior slabs. The reasons are explained herein.

First of all, whenever concrete changes from a semi-liquid or plastic (i.e. from fresh, ready-mix concrete) to a hardened state (i.e. cured-out), it undergoes a volume shrinkage. This volume shrinkage is primarily related to loss of water. Concrete generally consists of sand, portland cement, gravel and water. The water combines (chemically-reacts) with the portland cement to create the rock-like, hardened mass we call concrete. During this process, much of the water is used up. In addition, a significant amount of water is lost to either evaporation or seepage into the subgrade. To help prevent rapid loss of water in freshly placed concrete, especially during warm/hot/windy days, the finished surface of the concrete should be kept moist and covered with plastic or wet burlap for several days. (This helps to maintain moisture to slow down the moisture loss process.)

In spite of extended curing [in a moist state], the eventual loss of water in fresh concrete will cause a significant volume change (reduction) from the ready-mix to the final, hardened state. In relatively thin concrete slabs on grade, this volume change results in a significant dimension change in the surface (plane) of the slab. As the slab shrinks, frictional forces can be generated along its bottom face (due to contact with the subgrade); this can set-up tensile stresses in the concrete. Also, if the concrete loses moisture through the surface only, due to the presence of an underlying plastic vapor barrier, the top face of the slab will shrink more than the bottom. This causes the slab to curl up around the perimeter edges. Both of these conditions can lead to cracking, because both (dimension shrinkage and curling) set-up tensile stresses in the slab.

Tensile stresses are detrimental because, while strong in compression, concrete is very weak in tension; i.e., it is relatively easy to “pull-apart” plain (unreinforced) concrete. Therefore, steel (wire mesh) is embedded in concrete to provide it with the tensile strength needed to control crack formation. Effective steel reinforcement, however, is more easily attempted than accomplished. Unless the wire mesh is held up by closely-spaced chairs, it is not likely to remain properly positioned near the top-center of the hardened slab (the position at which it is most effective). The success of wire mesh in crack control depends upon whether the contractor/finisher systematically reaches down through the concrete mix with a hooked bar and pulls the steel mesh off of the ground and up into the plastic mix. Unfortunately, as is well documented, test cuts consistently show that these precautions are not taken; more often than not, the wire mesh is found lying on the ground, barely embedded in the concrete. Under these circumstances, it serves no purpose. It is also necessary to realize that larger slabs require larger steel for crack control. Engineers may be mindful of this, but few concrete finishers are.

Once an exterior concrete slab on grade is placed, finished, and cured, it is subjected to perpetual, direct weather exposure, including periodic (and sometimes drastic) changes in temperature and humidity. Because concrete tends to absorb and/or give off moisture according to the surrounding weather conditions, weather changes affect the concrete’s moisture content; and, along with any moisture content change comes a volume (dimension) change. Concrete also expands/contracts with changes in temperature. Hence, once hairline cracks form in concrete, the effects of Mother Nature usually start to take their toll: initially small, invisible shrinkage cracks later enlarge. Crack enlargement facilitates direct moisture penetration into the crack, which can lead to isolated subgrade saturation or freezing expansion of trapped water during extremely cold weather. (Everyone knows that water expands upon freezing; hence, trapped water inside concrete cracks can pry cracks apart during freezing weather.)

In addition, moisture that seeps into the subgrade beneath a slab on grade can affect the behavior of some soils–especially highly plastic or silty-clays. Highly plastic clay soils exhibit an electro-chemical affinity for water, actually incorporating water molecules into their chemical structure (crystalline lattice). Thus, these soils are typically called expansive clays. During the winter, which is the normal rainy season in North Alabama, these soils take on moisture and expand in volume. Soil expansion can lift up or heave a slab-on-grade. During the summer, when droughts and hot weather frequently occur, the soils desiccate and shrink in volume, causing slabs to sink or settle. Hence, changes in the subgrade moisture content can cause slabs on grade to “move” throughout the year. Fine-grained soils, like silts and clays, are also very weak when wet or saturated and easily yield (deform) under a load. Hence, placing concrete slabs directly on top of highly plastic clay soils is a bad idea–especially for driveways which support heavy vehicle wheel loads. There are many types of highly plastic silty and expansive clays in North Alabama. They typically occur above/around limestone bedrock deposits. Contact the county extension agent at the nearest USDA Soil Conservation Service to learn more about the locations of expansive clay soils in your area.

In addition to the adverse effects of shrink-swell soils beneath driveway slabs, consider the problems that water beneath slabs can cause. Water that penetrates slab cracks can puddle beneath slabs; then, whenever a heavy vehicle crosses the slab, it will deflect under the wheel load and force water from the underlying puddle through the cracks (this is called “subgrade pumping”). The water usually carries fine-grained soil particles from the ground with it. After a sufficient amount of erosion has occurred, a void typically forms beneath the slab; then, when a heavy wheel load crosses the slab, it could cause an isolated portion of the slab to collapse into the eroded hole, resulting in pavement failure.

Generally, closely-spaced control joints are installed in slabs to prevent/conceal unsightly cracks. Either pre-formed or saw-cut, control joints create pre-planned planes of weakness in concrete slabs, thereby predetermining straight (as opposed to random, jagged) lines in the slab surface.

Whenever an engineer or architect is left out of a concrete slab construction project, the concrete contractor is responsible for providing proper control joint spacing. A rule of thumb states that control joints should be spaced at intervals (measured in feet) equal to three times the slab thickness (measured in inches). In other words, in a 4 inch thick slab, control joints should be spaced at (4” x 3 = 12′) 12 foot intervals. Moreover, control joints should be placed in areas of abrupt slab dimension change. In order to be effective, saw-cut control joints must penetrate ¼ of the slab thickness. Hence, a 4 inch thick slab must have 1 inch deep, saw-cut control joints. In narrow pavements, like sidewalks, control joint spacings should range from what to no more than twice the width of the sidewalk. If wider control joint spacings are desired, steel reinforcement can be utilized to prevent random shrinkage cracking.

Another cause of concrete cracking is structural overload. Concrete slabs should be placed on well-compacted beds of gravel. This helps to provide uniform bearing pressure beneath the slab whenever it is exposed to surface loads. Heavy wheel loads, for example, are transferred through the slab and onto the subgrade. If the subgrade consists of weak or saturated soil, it will likely deform under the pressure. This can set up bending stresses in the concrete slab which, in turn, can generate adverse shear and tensile stresses. Under some heavy loads and poor subgrade bearing conditions, concrete slabs crack. As stated, this lets water seep into the subgrade and the application of future heavy wheel loads leads to a worsening condition (see the preceding discussion of “subgrade pumping”).

In summary, large, crack free, unreinforced concrete slabs on grade are rare. To have a long-lasting, aesthetically pleasing concrete slab on grade: utilize a high quality concrete mix with proper air-entrainment (see section on surface defects), place the slab on a well-compacted layer of gravel (subgrade), saw cut control joints at a close-spacing (throughout the slab) within 12 – 24 hours of placement (in order to provide pre-planned planes of weakness for crack control), then properly cure the slab for several days. You’ll find that, in a relatively short time, cracks will form at each of the control joints. You can seal these cracks with a commercially-available concrete crack sealer/caulking to preclude water entry. Other construction precautions include utilizing a quality concrete ready mix during placement and adding the least amount of water possible to the delivered concrete prior to placement. Proper curing entails wetting the surface of the concrete after finishing, then covering the slab with plastic or wet burlap. The concrete should be kept moist in this manner for as long as possible–at least three to seven days. If this is impossible, spray the slab with a commercial concrete sealer (according to directions of the sealer manufacturer). You’ll generally find that a very generous application of sealer is required to form a thick layer of surface sealer, i.e., one capable of preventing excessive moisture loss through the slab. Lastly, finished slabs should drain freely onto the adjacent ground or designated areas which direct runoff away from the slab.

For more information you can check out the web site called Concrete Basics from the Portland Cement Association.

A home-buyer transferring into the Huntsville metropolitan area once asked me, “What is the most common residential foundation problem that you see in your home inspection business?” I answered, “Differential foundation settlements (movements) due to expansive clay soils.” “Not so much expansion,” I explained, “but the opposite actually-or what we commonly call ‘shrinkage.’”

The residential foundation problems are related to volume changes in the clay soils which underlie the house. These particular clay soils have what engineers call a ” high plasticity”. This is a term that is used to describe a clayey soil which remains “plastic” (or in a “moldable” state), neither turning liquid nor crumbling apart, over a wide range of moisture contents. This is unlike other fine-grained soils (mixtures of sands, silts and clays) which either liquify or crumble apart at the extreme ends of a fairly small range of plasticity (moisture contents.) Liquifying or fluid flow occurs at the wet end of the moisture scale, whereas crumbling occurs at the dry end. Many of you might compare a highly plastic clay soil to the popular child’s toy, “Playdough®” in that highly plastic clays can be molded into various shapes or, when worked in between the thumb and index finger, one can form a long, thin “ribbon” of clay.

The reason why these soils remain plastic over such a wide range of moisture contents, is because they have an “affinity” or attraction for water. Actually, they have an attraction for the H2O water molecule. In order to understand this, you must understand that unlike silts or sands, clay particles are microscopic in size. We cannot see them with our naked eye. Walk along the beach and grab a handful of sand and you can easily sort out individual sand particles. You can’t do this with clay. The clay particles (actually platelets) are microscopic in size. They are, in essence, ions or molecules and they bond together (to one another). Most clay ions also chemically react or interact with the H20 water molecule. They usually want to bring in (attach) water molecules to their crystalline lattice (or molecular structure/chain).

Clay soils usually evolve from the weathering of minerals and, therefore, take on the mineral’s crystalline structure or chemical make-up. Typical clay minerals in our area are -silicates of either iron, magnesium or aluminum. Some clay soil minerals have a very high attraction for water. Instead of wanting to add one or two water molecules to their structure, they want to add many more. These are the expansive clays. When this happens, the individual clay ion’s crystalline structure or lattice dramatically grows in size. When all the millions and billions of clay ions/molecules underlying a foundation footing absorb large numbers of water molecules, the soil dramatically grows in size. In the real world, where we live, this volume change can be significant. The reverse is also true. And here is where the foundation problems seem to arise. Whenever the clay ions give up attached water molecules (from evaporation or plant root uptake) they shrink in volume. Extreme examples of this type of shrinkage are the formation of large cracks in the ground surface and/or the ground pulling away from a home/foundation during the hot, dry summer months or during droughts. Examples of foundation problems are differential settlements caused by shrinkage of the clay soil.

A simple analogy for this phenomena would be, “clay soils are like sponges”. Whenever sponges soak up water they swell in volume. When left on the counter to dry, however, they shrink back down to a very small size…only to puff-up again when placed into contact with water. Clay soils are also like sponges in that when they become wet, they become soft or softer. When dry, they become very hard. Place a heavy load on dry clay soil and it goes nowhere or settles very little. The ground will support a sky-scraper! When wet or saturated however, don’t even think about driving a riding lawn mower across the ground. It will sink up to its axle.

Hence, when living in a house constructed on highly plastic clay soils (particularly swelling clay soils) it is very important that the owner make sure that the drainage conditions around the home are monitored and maintained annually, so that surface water runoff always flows away from the home and never stands or ponds beside it. If this ever occurs, and the ground alongside and beneath a home (foundation footing) becomes wet or saturated during heavy rains or throughout the rainy season (due to poor drainage conditions, overflowing gutters, lack of gutters, etc.), then the house may slowly settle into the ground in the areas where the clay soil has become softest. This, alone, can lead to differential (or uneven) foundation settlement. But another, and often more serious problem occurs during the following summer or fall after the hot, dry weather we typically experience in the North Alabama geographic area. The soils that stayed extremely wet throughout the year, and swelled accordingly, shrunk dramatically by the time July and August rolled around. The portion of the house resting on this formerly wet ground also settles (dramatically) along with the shrinking clay.

Believe it or not, however, this common problem can always be avoided during foundation construction if builders would simply admit that these soil conditions exist and recognize that they need to have each building site evaluated by a professional soil scientist or geotechnical engineer prior to house construction. If not, it is likely that the builder will utilize the standard shallow-bearing foundation, and place the footings or foundation just below or within a few feet of the ground surface. Soil shrinkage-related settlements or movements will eventually lead to foundation settlement cracking and/or the formation of large cracks in brittle construction materials such as brick veneer and sheetrock. This is almost a guaranteed.

In my next article, I’ll discuss why plastic clay soils can cause 20 to 30 year-old houses to suddenly develop foundation settlement damage. I’ll also explain how to live in and/or deal with a home constructed on highly plastic clay soils by controlling the seasonal movements associated with shrinking clays, and I’ll tell how to go about repairing severely cracked and damaged houses.

It has been my experience that whenever an older home (say 15 to 20 years or more) that is constructed on highly plastic clay suddenly experiences cracking in brick or sheetrock, after many years of crack-free service, and there’s no other obvious answer to the problem, it’s probably related to drying shrinkage of underlying expansive clay subsoils. These subsoils probably remained wet each year, throughout the life of the home. Or, at least, the moisture change that did occur each year in the underlying massive clay soil was not sufficient to cause enough building distortion to, in turn, cause building material cracking. If the home suddenly develops cracks, however, there’s probably been some major change in the drainage conditions or landscape surrounding the home. For example, if the house originally had gutters and these served their purpose for many years, then, for some reason (frequent leaf/debris clogging hassles and subsequent rusting deterioration?), the owner removes them, the moisture conditions around the house suddenly change. My personal experience suggests that the effects of water falling beside the home will eventually begin to take its toll by eroding more and more surface soil– thus exposing the foundation footing and/or the underlying plastic clays to more and more solar radiation. At some time, say 20 years after construction, the effects of normal summertime drying shrinkage may finally cause soil shrinkage sufficient to create enough foundation distortion to bring about enough building distortion to in turn cause sudden building material cracking, such as cracks in brick or sheetrock.

Another problem that I’ve noticed over the past twelve years of inspecting houses, is that if a particular part of the crawl space or foundation remains moist or under standing water during most or part of the year, as evidenced by dark, water/algae stains on the concrete or concrete block foundation system, then the adverse effects of a summer drought are most pronounced on the underlying bearing soils in these wet areas. In other words, these soils go from the extreme wet end of the moisture scale to the dry end. Imagine: the larger the moisture change, the more the soil shrinkage and, therefore, the greater potential for foundation settlement.

A third problem is related to large trees. If hardwoods are planted near a home soon after construction, it is likely that in 20 to 30 years, the trees will overhang the house-which means that their roots underlie the house. These roots are going to contribute to soil desiccation during a drought by robbing the soil of all available moisture. Hence, whenever a hardwood or pine tree overhangs a home/roof built on a highly plastic clay soil site, the tree should probably be removed.

Regardless of trees and poor drainage conditions, if a house is initially built on a shallow foundation system which bears on expansive clay soils, then the house will likely move and distort from day one. Moreover, it is unlikely that this movement will be uniform because the moisture content around and beneath the home will not be uniform. It will vary because of different drainage conditions that exist, the varying degree of solar exposure and the presence of large trees or shrubs. As stated, trees are especially capable of desiccating (completely drying) soil during drought periods. In time, the effects of uneven foundation movement, or differential foundation movement/settlement, or simply building distortion, will take its toll on the home and cracks will begin to form in the more brittle materials. The cracks form to relieve the built-up stress of distortion.

What can be done to control the distortion?

The most economical way to deal with expansive clay soils underlying a home is to try and maintain a uniform moisture content in the ground (clay soil) throughout the year. This is best accomplished by letting nature takes its course throughout the wet winter, when rainfall is greatest and evaporation is lowest — then adding water via irrigation, as required, during the dry periods of the year. Drip irrigation tubing laid alongside the foundation footings, covered with thick beds of mulch, typically works well to do this. By applying water slowly, via the drip tube, the ground can absorb water previously lost or given up to evaporation and plant root uptake. One has to be careful, however, not to over-water or saturate the ground because as stated, this can soften the bearing soils and lead to foundation settlement. Any irrigation contractor should be able to come up with an automated drip irrigation system. In other words, moisture detectors can probably be buried below/beside the foundation and utilized to activate (automate) a drip irrigation system using a conventional lawn irrigation control panel. The buried sensors tell the irrigation control panel when to turn valves on and off. The irrigation contractor should work closely with a professional soil scientist to determine the range of soil moisture content readings that should be utilized to activate/deactivate the irrigation system.

In some instances, when the amount of differential foundation movement has been so severe that a foundation component has cracked and faulted, when doors and windows start to bind, or when the brick veneer has cracked, faulted and/or pulled away from the home, it might become necessary to underpin the distorted foundation so that future movements do not make matters worse. Foundation underpinning can also be used to uplift and/or relevel a settled (distorted) foundation.

Underpinning typically entails digging or drilling a vertical shaft into the ground, alongside and beneath an isolated part of the foundation, then filling the excavation with concrete. These shafts are usually spaced several feet apart so as to not undermine the entire foundation, which would obviously lead to collapse. In some instances the concrete is simply placed into the shaft until it contacts the footing, thus preventing future or additional settlement. In other cases, the concrete placed into the excavation is stopped a foot or more beneath the footing and allowed to harden or cure for several days. Large hydraulic jacks are then placed beneath the footing, on top of these concrete piers or shafts, and the footing is carefully jacked upward, extending the jacks in proportion to the amount of settlement at each point. It’s a real art (and danger) to relevel a settled house/foundation, so this type of repair should be left only to professionals.

A similar method of foundation repair entails the use of helical augers which are turned or twisted into the ground and stopped whenever the driving torque reaches a certain level — indicating that the blades on the auger have reached a sufficient bearing capacity with the deeper soil strata to provide a substantial amount of vertical support. Steel brackets are fitted over the auger shaft and under the foundation. The auger shaft is usually threaded, so large nuts placed below the bracket are turned in order to lift the footing upward.

There are many firms which specialize in this type of repair: Foundation and Structural Renovations (Huntsville), Hollis Kennedy House Moving (Athens), Alabama RamJack (North Alabama), AFS (North Alabama), Steve Reeves Construction (Decatur), and others.