Issues with Brick Veneer

Issues With Brick Veneer

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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 heavy 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 31 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.

Buck DurhamJADE Engineering & Home InspectionPresidentAlabama’s trusted leader in Engineering Inspections and Home InspectionsAlabamaUSinfo@jadeengineering.bizPhone: (256) 318-0982

 

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