Q--Every time a wind-blown rain saturates our brick veneer home, water streams into the house. I have noticed that the wood floors in our living room are warping as well. The brick and mortar appear fine. What is causing the leaks? What, if anything, can be done to stop the water penetration?
A--I hate to tell you this, but you have some very serious problems. If they aren't corrected, serious structural failure will result. I'm quite confident that if I examined your brick walls, I would find serious workmanship errors.
Virtually every brick wall will allow water to penetrate. The water has three possible paths. It can enter directly through the brick, the mortar and/or the contact zone between the brick and mortar. The primary path of water into brick walls is the contact zone between brick and mortar and mortar joints that are not completely filled. Your wall leaks, I will wager, are most likely originating at the vertical joints between many of the bricks. Bricklayers call these "head joints."
The quality, type and moisture content of the mortar is a critical factor in preventing brick veneer wall leaks. The mortar for a brick veneer house needs to have a high lime and low cement content. The lime in the mortar, through the years, can actually heal tiny cracks that might develop between the bricks and mortar. Fresh mortar that is too wet or has too much cement can shrink as it dries. This shrinkage can produce tiny cracks that allow water to easily penetrate the wall.
Older brick houses were rarely built with brick veneer. Often their walls were two, three and sometimes four bricks thick, bonded with lower strength, high-lime-content mortar. The inner courses of brick were very soft and absorbent. Rain water would collect within the wall and then be released to the atmosphere once the storm passed.
Modern, single-thickness brick veneer walls deliver the wind-driven rain within a matter of minutes to the wood frame system adjacent to the brick. This water needs to be collected and transported immediately to the exterior of the house. This is accomplished by installing high-quality flashing materials at the base of the brick wall, above all doors and windows, and below all window and door sills.
The flashing must be continuous and be made from a material that allows joints to be permanently sealed. High-quality brick veneer flashings can be made from modified asphalt and high-quality polyethylene and copper/asphalt combinations. It shouldn't be the low-quality "garbage bag" or PVC-type plastic, which is useless.
The exterior of your wood-framed walls should be covered with a water-resistant membrane. Overlapping horizontal pieces of tar paper will work. However, there are many air and moisture barriers that will do as good a job--or better--at preventing the leaking water from contacting your wood framing.
These moisture barriers must be installed so they lap over the wall flashings. Weep holes at the bottom of all walls and at the top of windows and doors need to be no less than 4 feet on center; 2 feet on center is preferable. The cavity behind the lowest courses of brick needs to be free and clear of mortar droppings. This allows leaking water to easily escape through the weep holes. An ingenious, saw-toothed plastic netting can accomplish this task easily. It fits behind the first few courses of brick.
You may be able to be stop your leaks by applying high-quality water repellents that contain special chemicals called silanes, siloxanes or a blend of the two. First, you must closely examine your brick walls. Look for tiny hairline cracks in the vertical joints. Remove and install new mortar if you find obvious water entry points. After the joints dry, apply the water repellents according to the manufacturer's instructions.
If this does not solve your leak problem, I'm afraid that your only solution might be to reinstall the brickwork properly.
Have questions about the remodeling process? Write to Tim Carter, c/o The Chicago Tribune, P.O. Box 36352, Cincinnati, Ohio 45236-0352. Questions will be answered only in the column.
For a list of silane/siloxane water repellents, detailed brick veneer wall construction tips, and additional literature resources concerning brick veneer leakage, send $2 and your name and address to Tim Carter at the above address. Ask for Builder Bulletin No. 193.
For a list of past Builder Bulletins and a wide variety of individual job bid sheets, send a business-size, stamped, self-addressed envelope to the same address.
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