Many of the homes around North Riverside have a factory-built fireplace housed in a wood-framed chimney chase — the tall boxed structure you see on the roof, often sided to match the house. On top of that chase sits a metal chase cover, and it is one of the most overlooked and most common sources of chimney leaks in prefab systems.
What a chase cover is
A chase cover is the metal lid that seals the top of a prefab chimney chase, with holes for the flue pipe to pass through. It is the prefab equivalent of a masonry crown. Cheaper builders installed galvanized steel covers that rust through in a handful of Chicago winters, and once they do, water pours straight into the chase and down around the metal chimney.
Signs a chase cover is failing
- Rust streaks running down the siding or brick of the chase
- Water stains on the ceiling near the fireplace
- A cover that has sagged or pooled water in the middle
- Daylight or gaps where the flue pipe passes through
- A musty smell from the firebox after rain
Why the material matters
A replacement chase cover should be stainless steel or aluminum, not galvanized, and it should be built with a slight slope and a water diverter so rain runs off instead of pooling. A quality cover lasts for decades and protects the whole prefab system underneath it. Pairing it with a proper cap on the flue pipe completes the seal.
Do not wait on a rusted cover
A failing chase cover does its damage out of sight, soaking the framing and corroding the metal chimney inside the chase long before you see a ceiling stain. If you can see rust on top or streaks down the chase, it is already leaking. Replacing it is far cheaper than repairing water-damaged framing and a corroded flue.
Homeowners in North Riverside can read more on our North Riverside chimney sweep page, or see our full chimney caps and crowns service.
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Call (708) 432-5330Frequently asked questions
What is the difference between a chase cover and a crown?
A crown is the concrete top of a masonry chimney; a chase cover is the metal top of a factory-built chimney chase. Both keep water out of the system.
How long does a chase cover last?
A galvanized cover often rusts through in five to ten years here. A stainless steel or aluminum cover lasts for decades.
How do I know if mine is leaking?
Rust streaks down the chase, pooling water on top, ceiling stains near the fireplace, or a musty firebox after rain all point to a failing cover.
Can a chase cover be repaired or does it need replacing?
A rusted-through cover is replaced, not patched. A new stainless cover with proper slope is the lasting fix.
Written by Adam Evans, owner of Chimney Sweep Brothers and a chimney technician with 12 years of experience serving La Grange, IL and the western suburbs.
Published: September 28, 2026