Published on February 23rd, 2015 | by Henri0
Bricks falling off chimney
Q. Our home is 25 years old. We noticed pieces of brick falling onto the garage roof. We have had a waterproof liquid coating put on two times in the last year. It has now been recommended to rebuild the entire chimney (an expensive proposition). Is this the only way to correct this? What would be the harm in just leaving it? We see no leakage or any other observable problem.
A. Spalling of brick surfaces is caused by moisture in the bricks that freezes before the bricks have had a chance to dry out. If the coating applied on your chimney is truly waterproof, it was a mistake to apply it. That simply prevented any moisture that had been in the bricks from drying out.
If this situation is not corrected, damage will continue and, eventually, the chimney will be beyond repair.
If the damage is not too advanced, a competent mason may be able to remove and replace the spalled bricks. But the cost of doing so may be close to, or exceed, the cost of total replacement. New bricks can receive a water-repellent coating, but not a waterproofing coating. Be sure it is siloxane-based.by