Chimney Flashing Repair in Brentwood: Written Report, Licensed Technicians

If you live along the Decker Canyon corridor or closer to the Lake Sherwood area near the Ventura County line approach, flashing repair on a standard single-story chimney typically runs between $450 and $1,200. That range depends on whether your chimney needs only step flashing replaced along the roof slope or a full counter flashing reset where metal is embedded into the mortar joints. Most homes in this stretch were built between the 1970s and early 1990s with aluminum flashing, which corrodes faster than lead in the salt-tinged air that pushes through the canyon. If the cricket behind your chimney has failed or was never installed, add $300 to $600 for fabrication and installation. We quote after a visual inspection, not over the phone.

Here is where energy efficiency and damper sealing change the math. When we open a chimney to repair flashing, we inspect the damper seal at the same time. A warped or poorly sealed damper lets conditioned air escape 24 hours a day, costing you more in annual energy loss than the flashing repair itself. If we find a failed damper during your flashing job, we can install a top-sealing damper during the same visit for a bundled price, typically $250 to $375 less than scheduling it separately. For homes near Decker Canyon that run their HVAC hard against summer canyon heat, that damper upgrade often pays for itself within two cooling seasons. We include this evaluation in every flashing repair scope so nothing gets overlooked.

Our technician starts by removing roofing material around the chimney base to expose the existing flashing. In the Lake Sherwood area and along the Ventura County line approach, we commonly find aluminum step flashing that has separated from the roof deck after years of thermal cycling. Canyon temperatures swing 25 to 30 degrees between morning marine air and afternoon heat, and that daily expansion and contraction loosens fasteners and breaks sealant bonds. We pull each piece of step flashing individually, inspect the underlayment for water damage, and replace any rotted decking before new flashing goes down. Step flashing gets layered shingle-by-shingle up the roof slope. Counter flashing is cut into a reglet ground into the mortar joint, then sealed with a flexible polyurethane caulk rated for UV exposure. We do not use silicone on masonry. It fails within three years in direct sun.

If your chimney sits on the uphill side of the roof, we install a cricket. A cricket is a small peaked structure that diverts rainwater around the chimney instead of letting it pool. Many Decker Canyon homes were built without one, and those chimneys show the worst leak damage we see. We fabricate the cricket from galvanized steel, flash it into the existing roof plane, and tie it into the new counter flashing. After the metalwork is complete, we check the damper from above with a mirror and flashlight. A damper that does not close flush means your home leaks air year-round. We document everything with photos and leave you a written report covering flashing condition, damper seal status, and any masonry concerns we spotted during the work.