How chimney leaks start
Chimneys interrupt the roof plane. Rain and melt water follow the path of least resistance — often behind loose step flashing or into gaps where counter flashing should be embedded in mortar.
New Hampshire homes with brick chimneys on north slopes see the worst ice buildup. Water freezes in small gaps, lifts flashing, and repeats every winter.
Signs to watch for
- Brown stains on ceiling or walls near the chimney chase
- Rust streaks on the chimney face below the cap
- Lifted or cracked caulk at the flashing edge (caulk alone rarely fixes it)
- Missing or bent step flashing visible from the ground with binoculars
- Musty smell in attic near the chimney framing
What a real fix includes
A patch might buy time, but lasting work usually means proper step and counter flashing tied into the shingle system, cricket or saddle on the uphill side for wide chimneys, and ice & water membrane in the valley.
On a full roof replacement, we rebuild chimney details from the deck up — not reuse bent flashing because it "still looks okay."