A chimney chase is the long, narrow space that runs from the fireplace up the chimney and through the roof. The chimney chase houses the flue pipe. It’s what you probably think of when you hear the word “chimney,” that rectangular structure on the roof of your house that smoke comes out of. They are usually constructed with steel studs or wood with the exterior made of lathe and stucco, wood siding, or brick/ stone veneer.
WHY IS A CHIMNEY CHASE IMPORTANT?
- A well-built chimney chase:
- Reduces the risk of fire
- Keeps your home warmer
- Supports its exterior
- Contains the chimney pipe safely
- Prevents water and pests from entering the house
Common issues associated with poorly designed chimney chases include:
Water buildup behind the siding
Unsecure framing to support the exterior
Problematic chase cover (a metal casing on the top of a chimney meant to keep out water and pests)
Insufficient fire blocking
Flashing installed incorrectly (Flashing is the sheet metal used to waterproof the angle between the chimney and the roof)
Lack of cricket (a ridge that diverts water from where the chimney meets the roof)
The most common problem with wood-framed chimney chases is poorly-installed top flashing that isn’t sloped to drain correctly.
Another problem associated with chimney chases can be the chase cover or chimney cap. If you have a prefabricated chase, then your chase cover came with the chase. Usually made of galvanized metal, chase covers wear quickly, some as soon as five years.
An initial indication of a faulty chase cover is rust. Rust stains are a bad sign because they could mean water is getting on the inside of the chase cover and inside the chase, which can cause wall damage inside your house. Rust on a chase cover necessitates immediate replacement.
While galvanized metal is the most cost-effective material, you can also get chase covers in stainless steel or copper for more durability and aesthetic appeal.
WHEN TO REPLACE A CHIMNEY CHASE
If you have cold air circulating in or around your chimney, chances are it may be time for a new chimney chase. In the 70s and 80s, many prefabricated chimneys came with chase covers that were improperly installed. Manufacturers built chimney chases with cheap materials and chase covers that only lasted a few years. And once the chase cover goes, if not replaced in a timely fashion, you will begin to have problems with your chase, as water can soak into the wood or drywall.