In typical home construction, the house and chimney are set on different foundations. Over time, these foundations may move in different directions, causing a gap to form between the chimney and the roof. It is important to create a barrier between the chimney and roof that is waterproof and flexible to avoid leaking.
Chimney flashing is a thin metal barrier made from aluminum, stainless steel, copper or even lead. The thin, flexible sheets are wrapped around the chimney where it meets the roof shingles. As rain falls, it is directed over the flashing and away from the chimney/roof gap.
Chimney Flashing Parts
Chimney flashing has three main components:
The back (upper) side of the chimney flashing provides a special case:
Before You Start, A Word About Safety
Working on roofs can be dangerous. Make sure that you take proper safety precautions and consider the use of roof brackets to create a stable work platform. A personal fall arrest system (made up of a safety harness, rope and roof anchor) is a strong deterrent to dangerous falls.
Be sure to check the weather before you begin. Only begin a roofing project on days that are predicted to be dry and calm. Also, be aware of activity on the ground. Dropped material or tools can seriously injure anyone standing below.
On Sheet Metal
Chimney flashing is made from thin, flexible sheets of metal. If you've never worked with sheet metal before, consider having your chimney flashing parts professionally made. Once you've carefully measured for each of the components you'll need, look for a local sheet metal fabricator who can fashion the parts for you.
If you need to cut parts to fit, be careful around newly trimmed parts-the cut edges will be extremely sharp.
Installing Chimney Flashing
It's important to clean your chimney after a long winter of using your fireplace. If you don't want to have it done professionally, you can buy your own chimney sweep brushes and do it yourself. There are a few things you need to consider before you buy these brushes.
It happens about this time every year, the first cold evening and you want to build a nice roaring fire in the wood stove to warm up the house. Completely forgetting you never cleaned the chimney at the end of the heating season last year, that nice thick coat of creosote has had all summer to dry out.