Chimney cap may be reason of bricks absorbing water
Q. I have an existing brick chimney that absorbs water. The water comes through and ends up around the roof line near the ceiling of my Deck house. As it absorbs more water, it keeps moving down through the bricks. A new shingle roof was put on this 1984 house two years ago. The roofer put a sealant on the outside of the chimney in the fall of last year, and it still leaks. How can he resolve this problem?
Via e-mail
A. The roofer may not be the person to solve the problem. There are several possibilities for the leakage. The chimney cap on a 23-year-old chimney may have cracks that admit water and melting snow, and the mortar joints between the bricks may need pointing up. Or the roofer may have used the wrong sealant. There may be a flashing problem, although this seems less likely, since you seem to think that the water permeates the bricks above the roof flashing.
Most chimney caps are made with mortar left over from the building of the chimney. The mortar is spread over the top of the chimney and is usually feather-thin at the perimeter. The mortar eventually chips away and breaks up along the edges, and cracks develop over the entire cap.
The best caps are those built of a minimum 2-inch-thick (preferably thicker) concrete, which overhangs the chimney by an inch or so and has a kerf under the overhang to prevent water from following the underside of the cap by surface tension and wetting the bricks. The mortar joints must be checked carefully and tuck-pointed if needed.
The best products to coat a brick chimney with are siloxane-based. One such coating is Amteco's Silox Seal A -- a one-part sealant that can be applied over similar aged sealants. Amteco also manufactures Silox Seal Masonry Water Repellent, which comes in parts A and B and needs to be mixed. The application of these products will not affect the color of the bricks but must be applied carefully by following the directions in order to be effective. Amteco's Silox Seal A and Silox Masonry Water Repellent can be purchased as follows: Midwest region: Amteco, Inc. 800-969-4811; West Coast region: FSC Distributors, San Diego, Calif., 800-579-8459; South and East Coast region: MFG Sealants, Atlanta, Ga., 800-297-7325.
Q. The recent nor'easter resulted in 6 inches of water in my basement. This is the only time in 25 years that such a flooding occurred. I am planning a drainage system and am not sure which is the best for my situation. Only one side of my home is typically affected when substantial rain falls. The neighbor on that side has always retained water but has French drains, a sump pump and a dry well. I have none of the above. Our collective problem is due to the sloping nature of the land. I am considering an outside underground system to collect the water before it enters my home. But how deep should the pipe be set? Or would an alternate internal system be more appropriate?
Union, N.J.
A. If your basement leaks during substantial rainfalls, it is likely caused by surface water. The simplest and least expensive solution is to check the grade on the affected side of the house. It may need to be raised, as long as you will be able to do so and keep the soil a minimum of 8 inches away from any wood that is not pressure treated. You may need to swale the ground to direct the water's flow to the lower slope of the natural grade.
However, if the leakage occurs several hours or days after such substantial rainfalls, it is likely caused by a subsurface water source. This is trickier to control. Probably the simplest way to deal with it is to have a basement-waterproofing contractor install a fiberglass trough against and at the base of the basement walls, leading to a sump pump. French drains can be helpful, but there is a lot of digging involved, and you can't ever be sure they will solve the problem.
Q. We want to get our basement finished and met with an Owens Corning contractor yesterday. He went over the pluses and minuses. But his estimate was well over double that of a Sheetrock basement. My question is how much, if at all, better is Owens Corning for a basement?
Via e-mail
A. There are a number of conveniences about the Owens Corning Basement Finishing System, but you pay dearly for them. If your basement is absolutely dry and has never leaked, you can safely finish it with regular construction methods; i.e. studs and drywall.
With standard construction, you will have to add insulation if you want to improve the comfort of the finished basement, but there is a very important caveat that also applies to the Owens Corning System: Adding full-wall insulation to a basement can cause foundation problems if you are in an area with significant frost. By reducing the heat loss through the foundation, frost can penetrate deeper into the ground and push the walls in. This is a particularly serious problem with concrete or cinderblock walls.
A conservative practice is to insulate to only 2 feet below grade unless you are absolutely sure that the backfill around the foundation is coarse, that there is a working foundation drain, and that the grade against the foundation is sloping away from it to allow fast disposal of surface water before it has a chance to percolate deeply.
© 2007, United Feature Syndicate, Inc.