Two-Thirds of "Chimney Leaks" Are Flashing
Water stain on the ceiling near the fireplace? Damp attic around the chimney? Homeowners assume the chimney is leaking. Two times out of three, the chimney is fine — it's the flashing that's failed. Flashing is the metal transition where chimney meets roof, and it's the most commonly botched detail in the entire roofing-chimney system.
The Four Ways Flashing Fails
1. Caulk instead of counterflashing. The all-time classic shortcut. Someone smears roofing caulk where metal counterflashing should be embedded in the mortar. It holds a year or two, then cracks — and water runs behind everything.
2. Surface-mounted counterflashing. Metal stuck to the brick face with adhesive instead of cut into the mortar joint. The chimney and roof move differently with temperature; surface-mounted metal separates, and the gap becomes a water channel.
3. Rusted-through step flashing. Old galvanized step flashing rusts, storm damage bends it, and some roofers reuse flashing that should have been replaced with the roof.
4. No cricket on wide chimneys. Chimneys over ~30 inches wide need a cricket — a peaked diverter on the uphill side. Without it, water ponds against the brick and forces its way in during every heavy rain.
What Proper Looks Like
Step flashing woven into the shingle courses, counterflashing cut and sealed into the mortar joints, quality metal throughout, and a cricket where the width demands one. Every layer laps over the one below. No caulk doing a metal's job.
Our flashing repair service | Describe your leak — where the water shows and when, and we'll diagnose it.