Chimney waterproofing stops rain from soaking through the face of the brick. Brick and mortar are porous. On an exposed chimney, wind-driven rain gets absorbed into the masonry, moves down inside the chimney, and shows up as a stain on the ceiling next to the fireplace that looks exactly like a flashing leak.
We use a breathable water repellent, usually a silane or siloxane product, applied with a low-pressure sprayer from the crown down. Breathable matters. Paint, clear acrylic sealers and cheap concrete coatings trap moisture inside the brick, and when that trapped water freezes, it pops the face off the bricks. A siloxane repellent lets water vapor out while keeping liquid water from getting in.
Before we apply anything, the chimney has to be sound. Open joints get chimney tuckpointing, and a cracked top gets chimney crown repair. Fresh mortar needs to cure first, so on a full restoration we schedule the waterproofing as a second visit.
We do a simple test on every job: spray the brick with water and watch where it darkens. Brick that turns dark fast is soaking up water. Call (833) 583-1301 to set up chimney leak repair and waterproofing.
