Chimney Flashing Repair & Replacement in Pinecrest

Which Side Is Leaking? Flashing Failures Around the Chimney, Face by Face

Chimney flashing is not one part but four, and each one fails in its own way. An apron wraps the downhill face and laps over the roofing below it. Step flashing climbs the two sides, one bent piece per course of roofing. A back pan, or the metal on a cricket, handles the uphill face. Counter-flashing then covers the upper edges of all three. The base pieces are fastened to the roof and the counter pieces to the chimney, so the two structures can move a little without tearing the seal. That split is why the position of the water inside the house says so much about which piece let go.

The uphill face takes the hardest load, because every drop running down the roof above the chimney arrives there at once. Oak leaves, twigs and palm fronds pile up in the same spot and hold water against the masonry long after a storm has moved on. A failing back pan tends to stain the ceiling or attic on the upslope side and soften the roof deck behind the stack, rot that often stays hidden until the roofing around it comes up. On a wide chimney the lasting fix there is frequently a cricket to split the flow, not another layer of metal or sealant.

Side leaks behave differently. They usually follow the wind, show up on one side of the chimney only, and trace back to a single course where a step piece is missing, cut short, or nailed through low enough to let water past. The front apron is less often the culprit, since water is already moving away from the chimney there, so a stain on the downhill side often turns out to be something else. On a wood-framed chase with a stucco skin, water that gets in through a crack or the chase top runs down behind the finish and comes out at the roof line, where it passes for failed flashing even when the metal is fine.

Brick chimneys have a version of the same trap. Masonry above the roof that soaks up rain can carry that water down inside itself and release it below the counter-flashing, which is why brand-new metal sometimes does nothing for a leak. The scope of a flashing repair, and so its price, comes down to how many pieces have failed, what the roof is covered with, whether tile or shingles have to come up and go back down, whether the deck under the chimney has rotted, and whether a cricket has to be framed. Salt air and hurricane season mostly shape the choice of metal and how generously the pieces overlap against rain pushed sideways.

Why Flashing Is an Assembly, Not a Product

Flashing that works is two overlapping layers. Step flashing goes under each course of roofing and turns up the masonry; counter-flashing is cut into a mortar joint and laps down over it. Neither does the job alone, and sealant smeared across the junction is not a substitute for either.

Reglet depth decides whether the counter-flashing stays put. Cut too shallow and it works loose in the first storm season; cut into the brick instead of the joint and you have weakened the unit. We cut the joint, set the metal, and seal the reglet rather than the whole seam.

The failure signature is specific: water only after wind-driven rain, and often only from one direction. A leak that shows up twice a year is still a leak, and it is usually flashing rather than the crown.

Roof type changes the detail more than people expect. On barrel tile the flashing has to weave through the pans rather than lie on top of them, and a flashing job executed as though the roof were shingle leaks at the first storm regardless of how much sealant went in.

It also decides scope. Where tile has to come up for the work to be done properly, that is roofing alongside masonry, and we say so before starting rather than doing half a job that looks finished from the ground.