Clay Lamb

Diagnose Your Chimney's Leaking Problem



Posted: Saturday, June 05, 2010

by Clay Lamb
Fireplace and Chimney Supply

Water that enters the home can cause many problems from unsightly stains to unhealthy mold growth. Tracking the source of water entry should always be a process of elimination, beginning with the least expensive repair. When you are beginning to diagnose the problem, be looking for tell-tale signs of water entry, such as loose mortar joints, cracked brick, or a shifting foundation. All of these areas and more can allow water to enter into your home, making the diagnosis and correction of water problems very difficult.

Any obvious cracks in the brick are a starting point for inspecting points of entry of water. You can check to see if cracks are your issue by waiting for the interior to dry completely and begin spraying your chimney with water from the foundation up, gradually moving to see if, at a certain height on the chimney, moisture begins to appear in the home once more. If you come to diagnose your problem at a particular height on the chimney, you should seal the cracks with a brick sealant, repair any loose mortar joints between the brick, and apply a water repellent to the entire chimney.

Choosing the right water repellent is sometimes half the battle. Be sure that your water repellent will not trap vapors inside the brick, as this would only worsen your problem. Utilizing water repellents, like those manufactured by ChimneySavers, which form a semi permeable membrane over the brick is ideal. Such water repellents will allow vapors that naturally occur in small percentages in the brick to escape will still preventing new precipitation from entering the home.

If the integrity of the brick seems sound, and the foundation seems to be proper, you may want to inspect your flashing. ChimneySavers has an interesting product called FlashSeal, a flexible flashing sealant with an easy brush-on application, specially formulated to seal your flashing and prevent water entry. This sealant forms a permanently flexible membrane such that it will not cause damage to the roof or the flashing as fluctuations in temperature cause the materials to expand and contract. Temperature changes between day and night and from season to season cause shingles, flashing, and even brick to expand and contract on a molecular level. Sealants must be flexible or else they will cause damage to the shifting particles of the roof.

One gallon of FlashSeal covers approximately 28 sq. ft. You must apply the product in temperatures that are above 45 degrees Fahrenheit, and apply it with a brush. This product, FlashSeal, permanently adheres to most materials; metal flashing, asphalt shingles, brick, etc. This product is another option in the process of elimination to diagnose exactly where water is penetrating your home.

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Clay Lamb is a chimney expert and owner of American Chimney, in Cincinnati, OH. In 1981 he started a part-time chimney cleaning company. That was over 28 years and more than 75,000 service calls ago. He has helped thousands of homeowners solve problems with brick repair and chimney repair.
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Top-level comments on this article: (1 total)
» left by Jennifer Stewart
 1 year 329 days ago.
151 fans.
I think it's great to have this kind of knowledge - even if you don't want to fix a problem yourself, you can at least know whether the contractor you use knows what they're doing.
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