The interior of the home; that’s where a family spends most of the time during everyday living. Jade Home Inspection understands how important safety and comfort are to a family’s well-being…we have families of our own! That’s why we take our job seriously as we inspect each home for possible safety issues and potential problems. Here are just a few areas that our Interior Inspection covers when it comes to interior issues: Carbon Monoxide Dangers, Aluminum Wiring, Hardwood Floor Problems, Sheetrock Cracking, Particle Board Issues, Foul-Tasting Water, Mold, Dust, Mites, and Dust Mites.
Carbon Monoxide Dangers
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. [/learn_more]
Aluminum Wiring – Potential Fire Hazard
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.[/learn_more]
Hardwood Floors – Problems and Cures
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
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. [/learn_more]
Particle Board
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. [/learn_more]
Foul-Tasting Water
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. [/learn_more]
Mold, Dust and Mites
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 [/learn_more]