Chimney Flashing Repair in McMinnville, Oregon | Seal the Roof-Chimney Junction Right

Chimney flashing is a system of metal pieces that waterproof the gap between the chimney and the roof. The gap exists because the chimney and the roof are two separate structures that move independently. The roof expands and contracts with temperature changes. The chimney settles and shifts with the soil. Wind pushes on both. Over time, that movement separates the seal between them, and water finds the opening.

A typical chimney flashing system has two layers. Step flashing consists of L-shaped metal pieces woven into each course of roof shingles along the chimney’s sides. Counter flashing is a second layer of metal embedded in the chimney’s mortar joints that folds down over the top edge of the step flashing. Together, the two layers create an overlapping barrier that directs water down the roof and away from the junction. When either layer fails, water bypasses the barrier and enters the roof structure below.

In the Willamette Valley, flashing failures happen for a few consistent reasons. The sealant that bonds counter flashing to the chimney mortar joints dries out and cracks after years of sun exposure on the south and west faces. Galvanized steel flashing corrodes over time, especially on chimneys exposed to persistent moisture. Builder-grade installations on newer homes sometimes use inadequate materials or skip the counter flashing entirely, relying on caulk alone to seal the chimney-to-roof connection. Caulk on its own lasts three to five years before it pulls away from the chimney face.

We see flashing problems at every age of construction in this area. Older homes in downtown McMinnville and the established neighborhoods often have original flashing that’s been patched and re-caulked multiple times over the decades. The patches eventually cover so much of the original metal that the system no longer functions as designed. Newer homes in subdivisions around the Baker Creek area and the edges of McMinnville sometimes have flashing that was installed quickly during construction without proper step and counter flashing layering. In both cases, the fix is the same: remove the failed material and install new flashing correctly.

Our repair process depends on what’s failed. If the counter flashing has separated from the chimney face but the step flashing underneath is intact, we can re-embed or replace the counter flashing without disturbing the roof. If the step flashing has corroded or shifted, we lift the adjacent shingles, remove the failed step pieces, install new ones woven properly into the shingle courses, and lay new counter flashing over the top. For chimneys where the entire flashing system has failed, we strip everything and install a complete new system from scratch.

We use aluminum or steel flashing depending on the application and the existing roof materials. All counter flashing is set into reglets (slots cut into the mortar joints) and sealed with high-grade polyurethane sealant rated for exterior masonry adhesion. We don’t rely on surface-applied caulk as the primary seal. The mechanical connection into the mortar joint is what makes flashing last.

Signs your chimney flashing needs repair

Water stains on the ceiling near the chimney, particularly on the uphill side where roof runoff hits the chimney, are the most common indicator of a flashing failure. The stain may appear only during heavy rain or during storms with wind from a specific direction, which narrows the leak to the corresponding side of the chimney.

Visible gaps between the flashing metal and the chimney face are something you can spot from a ladder or sometimes from the ground with binoculars. If the counter flashing has pulled away from the mortar joint and you can see daylight behind it, water is getting in during rain. Rust stains running down the chimney from the roofline indicate the flashing metal is corroding.

If you’ve had roof work done recently and the chimney starts leaking afterward, the roofers may have disturbed the flashing during the re-shingle and not replaced it properly. This happens more often than it should because general roofing crews don’t always understand chimney flashing as a system. If the leak started after a roof job, the flashing connection is the first place to check. A Chimney Inspection will confirm whether the flashing is the source and how much of it needs replacement.