Counter flashing repair fixes the part of a chimney flashing system people see from the street: the metal band set into the brick that laps down over the step flashing. When it pulls loose, water gets behind it and runs down inside the flashing instead of over it.
The right way to install counter flashing is to grind a reglet, a slot about an inch deep, into a mortar joint with an angle grinder and a masonry blade. The top edge of the metal is bent back into that slot, wedged, and sealed with a polyurethane or butyl sealant rated for masonry. On a sloped roof the counter flashing is stepped so each section follows a mortar course.
What we find on a lot of leak calls is counter flashing surface-mounted with a bead of silicone and a few masonry nails. Silicone does not bond well to dusty brick, and sun cracks it within a few seasons. Once the bead lets go, the chimney leaks every time it rains sideways.
We replace bent or rusted pieces, regrind the reglet where the old mortar is soft, and reset the metal. If the brick itself is crumbling where the slot goes, we handle that with chimney tuckpointing first. Call (833) 583-1301 for chimney flashing repair on your roof.
