Chimney Flashing Repair in Brentwood: Written Report, Licensed Technicians

A straightforward step flashing repair on a standard masonry chimney in Brentwood typically runs between $450 and $1,200, depending on how many courses need replacement and whether the counter flashing has to be recut into the mortar joints. But if your home started with a prefab fireplace and you've since done a prefab-to-masonry conversion, the scope changes. Converted chimneys often sit on a chase that wasn't originally designed for the weight and thermal movement of real brick or stone. That means the flashing tie-in at the roofline may need a full rebuild, not just a patch. For homes along the Pacific Palisades hillside, where steep roof pitches meet tall chimney stacks, that rebuild can push the job to $1,800 or more because of access difficulty and the need for a properly sized cricket behind the chimney.

In the Riviera section, we see a different pattern. Many of those homes were built in the 1950s and 1960s with original masonry chimneys, but decades of minor seismic settling have pulled the counter flashing away from the brick face by fractions of an inch. Enough to let rain in, not enough to notice from the ground. A Level 2 inspection with a camera scan catches these gaps before they rot the roof deck. We use lead flashing on most Brentwood jobs because it conforms to irregular surfaces better than aluminum, and it holds up to the salt-heavy air that rolls in off the coast. Aluminum corrodes within five to eight years here. Lead, properly installed, lasts twenty or more. The price difference is roughly $150 to $300 per chimney, and it pays for itself in avoided callbacks.

The technician starts with a leak diagnosis, because flashing isn't always the culprit. A cracked crown or deteriorated mortar cap can send water down the chimney exterior in a way that looks identical to a flashing failure from inside the attic. We run a controlled water test, directing a hose at the chimney-to-roof junction for fifteen minutes while someone watches from below. Once we confirm the flashing is the source, we strip the old material completely. On prefab-to-masonry conversions, this step often reveals surprises: the original chase cap was sometimes left in place under the new masonry, creating a hidden channel where water pools. We remove any compromised substrate, replace rotted sheathing if necessary, and install an ice-and-water shield membrane before any metal goes down.

Next comes the step flashing itself. Each L-shaped piece of lead is woven between the shingle courses so that water hitting the chimney wall gets redirected onto the roof surface below. On steep Sunset Mesa rooflines, we overlap each piece by at least three inches instead of the standard two, because the velocity of rain runoff is higher on pitches above 8:12. After the step flashing is set, we cut a reglet groove into the mortar joint and seat the counter flashing with high-temperature sealant rated for masonry chimney repair. If the chimney is wide enough to warrant a cricket, we fabricate one on-site from sheet metal and tie it into the existing roof plane. We follow NFPA 211 inspection standards during every step, and we document the work with photos for your records and your insurance file.

Timing matters in Brentwood. SoCal's rain season typically starts in late October, and the ground along the Pacific Palisades hillside stays saturated well into March during heavier years. We recommend booking flashing work between June and September, when we can guarantee dry conditions for sealant cure times and membrane adhesion. Waiting until you spot a ceiling stain usually means the roof deck has already absorbed moisture, which turns a flashing repair into a flashing-and-sheathing repair.