Caps · Flashing · Water at the chimney
Chimney caps and chimney flashing
A cap keeps rain, snow, animals and debris out of the flue. Flashing keeps water out where the chimney meets the roof. Both are roof work, and both are worth checking before winter.
What a chimney cap does
An uncapped flue is an open pipe into the house. Rain runs straight down it, wearing on the flue liner and the masonry, and birds, squirrels and leaves find their way in. A cap with a hood and mesh sides keeps most of that out while still letting the chimney draw.
Caps, crowns and flashing are different things
- Cap: the metal hood over the top of the flue, usually with mesh sides.
- Crown: the masonry or concrete top of the chimney around the flue, shaped to shed water.
- Flashing: the metal at the base of the chimney where it passes through the roof.
A leak that shows up near a chimney can come from any of the three, so it pays to check them together.
Signs your chimney needs attention
- Water stains on the ceiling or walls beside the chimney
- Dripping or rust inside the fireplace or on the damper
- Animal noises or nesting material in the flue
- Flashing that is lifting, rusted or patched with tar
- Cracks or missing pieces in the crown
Who does what
Caps and flashing are roofing and sheet metal work. The inside of the flue is a different trade: the NFPA 211 standard calls for chimneys, fireplaces and vents to be inspected at least once a year, which is a job for a chimney sweep. If the masonry itself is failing, a mason is the right call. Getting the cap and flashing right keeps water from undoing their work.
FAQ
Chimney caps: common questions
Do I need a chimney cap?
For most working chimneys, a cap is a simple way to keep rain, animals and debris out of the flue. A cap with mesh sides also helps stop sparks from landing on the roof if you burn wood.
What size chimney cap do I need?
It depends on the size and shape of the flue, and on whether the chimney has one flue or several. Single-flue caps fit over one flue; larger caps can cover a whole chimney top with multiple flues.
Why is water coming in around my chimney?
The most common cause is failed flashing where the chimney meets the roof. Cracked crowns, missing caps and porous masonry can also let water in, so all of them should be checked together.
- Phone
- (610) 432-9870
- Fax
- (610) 433-3863
- Message
- Use the contact form