Because chimneys extend above the roof and are continually subjected to the elements, waterproofing is an important measure to take to keep moisture out and protect mortar joints. Waterproofing maintains the integrity of insulation and prevents staining, water damage, and ultimately structural failure. Chimney sweeps generally follow a number of steps when waterproofing a chimney.

Ways a Chimney Sweep can waterproof your chimney

First of all, a chimney sweep will test the material being applied in an inconspicuous spot to ensure that it adheres and dries properly and to the homeowner’s satisfaction. The surface will be thoroughly scraped and cleaned to remove debris and leave it ready for the taping of seams and the application of a coating material. Taping reinforces seams, cracks, and joints and prevents the seepage of water. A primer is then applied over the tape before a top coat is painted onto the chimney. Generally, this dries within a couple of hours and requires 24 hours to cure.

Most coatings need to be applied under sunny skies when temperatures are between 40 and 90 degrees Fahrenheit. High humidity and low temperatures increase the drying time. When having this maintenance done, it is best to wait for the proper weather so the treatment is not compromised.

It is also important to distinguish between brick sealers and waterproofers. Sealers leave a surface film on the chimney which is water resistant and traps water vapors. If these vapors cannot escape, they will eventually cause the brick to deteriorate, so it is essential for the coating to breathe. A good chimney sweep will discuss this with the homeowner.

Finally, mortar joints need to be in good condition before the waterproofer is applied. This may require tuckpointing, which involves fresh mortar being slathered into the damaged joint. If mortar cracks are relatively minor, it may be possible for the chimney sweep simply to brush on a sealant, similar to a caulk which dries clear. This generally works for gaps that are less than 1/8th of an inch.