Chimney Leaks
A chimney is a hole in the roof with a brick tower on top of it, and it leaks in four distinct places. Knowing which one you have decides whether this is a roofing repair or a masonry one.
The four sources
- Step flashing up the sides — individual pieces woven into the shingle courses. If they were replaced with a continuous strip and caulk, that is the leak
- Counterflashing, which should be let into a mortar joint rather than sealed to the face of the brick
- The crown — the concrete cap on top. Cracks there let water straight into the masonry
- The masonry itself, on older chimneys where mortar joints have eroded and brick has spalled
The cricket question
A wide chimney on a sloped roof needs a cricket — a small peaked structure behind it that diverts water around rather than letting it pile against the back. Many Sacramento homes that need one do not have one, and the back of the chimney is where they leak.
Adding a cricket is more involved than replacing flashing and it is sometimes the only repair that actually works.
What a correct repair involves
- Shingle courses lifted and new step flashing woven in piece by piece
- Counterflashing let into a cut mortar joint, not surface-sealed
- Crown repaired or replaced where cracked
- Rotted sheathing behind the chimney replaced, which is common because the back is where water piles
- A cricket added where the chimney width and roof pitch call for it
What does not work
Tar or sealant across the joint between chimney and roof. It is the most common thing we find and the most common reason a chimney leak was never fixed. It looks like a repair from the ground and it has a life of a few seasons.
Common questions
Why does my chimney leak only on one side?
Usually the back or the uphill side, where water running down the roof piles against the masonry. That is the side that needs a cricket, and the side where sheathing rot is most often found.
Is a chimney leak a roofer's job or a mason's?
Flashing and sheathing are roofing. A cracked crown, eroded mortar joints and spalled brick are masonry. We will tell you which you have, and we hold a General Building licence so both can sit under one contract where both are needed.