The homeowner's concern
Water staining appeared on the interior chimney chase during the first heavy rain of the season, then again three weeks later. The homeowner had already had the chimney crown sealed by a masonry company with no change.
What the inspection found
- Step flashing on the uphill side of the chimney had been face-nailed and sealed with mastic that had cracked
- No cricket behind the chimney — water was ponding against the masonry on the high side
- Counterflashing was surface-mounted with sealant rather than let into a reglet joint
- Shingles in good condition with useful field life remaining — no replacement warranted
- Attic inspection showed staining limited to the chase framing, no sheathing rot
Scope of work performed
- 1Removed shingles around the chimney perimeter to expose the deck
- 2Fabricated and installed a sheet-metal cricket behind the chimney to divert water
- 3New woven step flashing on both sides, integrated shingle-over-flashing in correct sequence
- 4Cut a reglet into the mortar joint and installed let-in counterflashing, sealed with polyurethane
- 5Relaid shingles with new starter and ice-and-water membrane at the transition
Materials specified
26-gauge painted galvanized step flashing and custom-fabricated cricket
Let-in counterflashing with polyurethane sealant
Self-adhering ice-and-water membrane at the chimney transition
Color-matched GAF Timberline HDZ shingles for the repair area
Project photos
All photos on this page were taken by our crew on this job in San Diego County.
Outcome
The leak was traced to the flashing detail rather than the masonry, which meant a one-day repair instead of a chimney rebuild or a premature roof replacement. The chase was dry through the remainder of the rainy season and the repair carries a written workmanship warranty.