The importance of chimney waterproofing is widely understood, but this does not make the task an easy one. With so many different types of products on the market and the different types of chimneys, there is enough information out there to confuse the average person. Making a selection starts with a number of questions. Is the chimney made of concrete blocks, bricks or stone? Is the chimney currently leaking? The way you answer these and other questions will tell you what steps to take.
If an examination reveals damage to the brick, or spalling, there is no point in trying to waterproof it. The first thing to do is carry out repairs, which may mean a replacement, and then you can protect it against water intrusion. Bricks are porous, but there are different types, so the type of waterproofing material will depend on the porosity. You will need a waterproofing product that allows the bricks to breathe. Any moisture that does manage to seep in will be able to evaporate.
The Chimney Crown
Most chimney crowns are made of mortar or concrete, so they are porous. Waterproofing the crown is a bit different from waterproofing other parts of the chimney. Some concrete crowns so well done that the surface is not porous, but you should not take this for granted. Exposure to the elements suggest that you should take more precautions with this section of the structure. It is best choose a waterproofing product made specifically for crowns. Clean the surface properly before application, and follow the instructions provided.
Even flashing that seems to be in good condition can benefit from some extra work. Again, there are waterproofing products specific to this area, so do not buy basic sealants to protect it. These products are usually resin based, and they form an effective seal to keep water out.
The Chimney Breast
This area might require more than one coating of the waterproofing material. Water based sealants are more effective on vertical sections of the chimney. On horizontal surfaces, repeated coatings may be necessary, or you should choose a solvent based product.
A qualified chimney sweep will be able to offer advice on sealant products. You can seal the chimney yourself, but sometimes it is best to leave it to an expert. Like other aspects of chimney maintenance, it is best to get the waterproofing out of the way early.
Lou Curley’s Chimney Service is a local, family-owned and operated company with two CSIA Certified Chimney Sweeps to better serve homeowners along the Main Line. Give us a call at 610-626-2439 to schedule an appointment for advice on chimney waterproofing, chimney cleaning or inspection. Also follow us on Facebook for even more great information about keeping your chimney safe for years to come.