Chimney Flashing Repair in Walnut Creek, CA

Chimney flashing is the layered metal system that ties a chimney into the roof plane. It starts with apron flashing on the low side, step flashing woven into each course of shingles up both sides, and counter-flashing cut into the masonry.

On mid-century modern homes from the 1950s and 1960s, we usually find the original tar and roof cement dried to a crust. Water wicks behind it, soaks the decking, and rots the rafter tails long before a stain shows on the ceiling.

Contemporary homes built in the 1990s and 2000s often have a metal chase instead of masonry. Those joints tend to fail at the fasteners, not the metal.

Spanish and Mediterranean revival style homes add stucco to the mix. Stucco moves at a different rate than roofing does, which is exactly where counter-flashing earns its keep.

Strong afternoon winds drive rain up under the flashing on the windward side, and occasional hail dents aluminum until it lifts off the sealant bead. Copper and lead cost more and outlast several rounds of the same patch job.

Not every chimney leak is a flashing problem. A face-nailed drip edge, a valley that dumps straight onto the chimney, or an ice dam at the eave all show up as a ceiling stain near the fireplace.

We check pipe boots and vent boots above the chimney too. A cracked boot flashing at a plumbing stack leaks in the same spot and gets blamed on the masonry every time.

We also look at what sits next to the chimney. Soffit and fascia rot below it usually starts at the gutter, not the roof.

A ridge vent cut too close to the chase, a sagging ridge beam, or a parapet joint on a commercial building will all send water to the same ceiling stain.