HOW DO I…Stop water from coming in through my chimney?

  • Posted: Tuesday, November 12, 2013 5:58 p.m.

One homeowner was sharing his story about a stubborn leak coming in around his chimney area and showing up as a water stain in his ceiling. He had recently had his roof replaced, but after every heavy rain the leak continued. After having the roofer come back several times to redo the flashing around the chimney, they were looking for other solutions.

On top of masonry chimneys, built during the time Nixon was being grilled over Watergate as well as years before and after, the top of the brickwork was capped with a bed of mortar that was installed with a crown built in to shed water from the chimney. The problem with that is the mortar cracks open and separates along the edge of the cap, allowing water to seep in and infiltrate down through the brick work where some amount of water can find its way inward toward the ceiling.

I have seen the results of this issue cause rot inside of walls. There are several ways to approach this problem. A quick and inexpensive method is to seal the cracks and edges with a flexible caulking sealant. This can work fairly well as long as the sealant is applied completely and thoroughly. The problem with this method is that sealants have a tendency to void open. That is, a slight crack can develop between the sealant and the mortar it is intended to seal. Another problem is that it won’t stop new cracks that may develop in the mortar cap.

A more thorough approach and a little more expensive is to coat the entire surface of the mortar cap with a coating that completely covers the entire surface of the mortar cap. There are several brands available on the market for this type application. Sure Coat and Solar Flex are a couple. The process involves applying a liberal application of the base coat, then while it is wet, embed the re-enforcing fabric into the wet base coat. Apply a top coat over the fabric, making sure to cover the entire surface very thoroughly. The coating can be applied with a brush or roller or the combination of both. Make sure to “push” the fabric down into the wet base coat with the brush and/or roller so that it becomes totally immersed within the coating, eliminating all air bubbles. It would be important to bring the bottom edge of the coating and fabric down below the edge of the mortar and onto the top row of brick so that the drip line would be below the old crack between the mortar and top of the brick chimney. If the color of the roof coating clashes with the color of the brick, you can recoat the exposed edge with paint that matches the brick more accurately.

One other option would be to fabricate a metal chimney cap and secure it to the top of the chimney. Usually this would be fabricated by a metal fabrication shop or a welding shop. I used to have them made by Southern Roofing’s metal fab shop back when Jim Wells was operating the business in Augusta. Depending on the overall size of the chimney, these chimney caps can be quite heavy and bulky to get up in place. The metal roof of these caps would direct the majority of rain water off beyond the edge of the brick work. The cost for this method is usually more than any of the other options and sometimes it can look clumsy and out of balance if not designed properly.

JD Norris is the owner/operator of DreamMaker Bath&Kitchen and a certified S.C. Master Builder, certified “Aging in Place” Specialist and certified Green Professional. If you have any projects that you would like discussed in an upcoming article, email me at jdn.dm@comcast.net.

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