Custom Chimney Chase Cover
This is a custom chase cover, cut and formed to your measurements, for the top of a chimney chase. A chase is the framed, sided box that hides the chimney pipe of a factory-built fireplace, and the cover is the metal pan that seals its top. The original one is usually thin galvanized steel, and when it rusts through, water goes straight into the chase, the framing and the fireplace below. This one is stainless steel or copper, so it does not rust, and it is built to your chase, your pipe and your hole positions. Enter the measurements in the configurator above, choose the material and gauge, place the holes, and the price updates as you go. The Export PDF button saves a drawing of your cover to check on the roof or hand to your installer.
- Fits: framed chimney chases and flat masonry chimney tops, one to three chimney pipes, virtually any length and width.
- Material: 304 stainless steel in 24, 22 or 20 gauge, or copper. Powder coat in any RAL color over stainless.
- Built in: 3-inch skirt, X bend across the top, half-inch drip edge.
- Holes: round or rectangular, each with a 2-inch collar, placed exactly where your pipes are. Storm collars optional.
- Mounting: pre-drilled holes in the skirt, or in the top, if you want them.
- Built to order for you. Not returnable.
How to measure
Everything is measured on the roof with a tape measure, to the nearest quarter inch. The cover fits over the chase like a lid on a box, so all measurements are on the outside.
| Measurement | Where | What to enter |
|---|---|---|
| Length and width | The outside of the chase at the very top, edge to edge, the long way and the short way, including the siding or trim the skirt will cover. | Length is the longer number, width the shorter |
| Skirt | How far down the side of the chase the cover should reach. 3 inches is the standard and covers the top of the siding. | Skirt (S) |
| Pipe diameter | The outside diameter of the chimney pipe where it passes through the top of the chase. | Diameter (D1) |
| Hole position | From the outside of the chase to the nearest side of the pipe, on all four sides. | The four edge distances, or Centered if the pipe is in the middle |
Three things to check while you are up there. Squareness: measure each side at both ends and the two diagonals, and use the largest numbers. The top of the chase: the cover needs a flat, solid top to sit on, so rotten framing or a sagging old cover should be dealt with first. The pipe: note whether it has a storm collar and whether the cap is worth keeping.
Not sure? Send us the numbers and a photo of the chase top before you order, and we will check them. Every custom cover is checked by a person before it goes to the shop.
Choose your cover
Cover type
Single, double or triple hole, one for each chimney pipe that comes through the chase. Each hole is placed and sized on its own.
Material and gauge
304 stainless steel is the standard: it does not rust, needs no maintenance, and weathers to a soft grey. 24 gauge suits most chases; step up to 22 for large covers or heavy snow, and to 20 for very large chases. Copper is made to order for homes with copper accents. Powder coat over stainless comes in any RAL color, to match the siding, the roof or the cap.
Chase box
The skirt is the vertical edge that drops over the chase, 3 inches as standard. The X bend is a shallow crease across the top that stiffens the pan and sends water to the edges instead of letting it pool. The half-inch drip edge is a fold at the bottom of the skirt that throws water clear of the siding. Both are on by default.
Holes
Each hole can be round, for chimney pipe, or rectangular, for a masonry flue or a square termination. Every hole gets a collar, an upstand 2 inches high as standard, so water on the cover cannot run down the pipe. Add a storm collar if the pipe does not have one: it is the cone that sits above the collar and sheds water over it. Place each hole by its distance from the edges of the chase, or center it with one tap.
Mounting holes
Skirt holes are the usual choice: the screws go sideways through the skirt into the framing, where they cannot leak. Top holes are for a cover on a flat masonry crown that cannot be screwed from the side. Leave both off if your installer prefers to drill on the roof.
What arrives
- The cover, formed to your measurements, with the collars fitted.
- Storm collars, if you added them.
Custom covers are built after you order. We will confirm the build time and shipping date when your order is checked.
Installation
A one-person job for anyone comfortable on the roof, with a drill, a screwdriver and a caulk gun. Take the chimney cap off the pipe. Lift the old cover off, or cut it free if it was screwed down, and check the top of the chase for soft wood. Set the new cover over the chase and lower it until the skirt sits down over the siding. Fasten through the skirt with stainless steel screws, three or four per side; ordinary screws rust and streak the siding. Seal the collar to the pipe with high-temperature silicone, slide the storm collar down onto it and seal that too. Put the cap back on.
- Use stainless steel screws and a high-temperature sealant only.
- Do not screw through the top of the cover unless you ordered top holes, and seal every top screw.
- Keep the pipe's clearances to the framing as the fireplace manual shows; the cover does not change them.
Specifications
| Type | Chimney chase cover, custom size, one to three holes |
|---|---|
| Material | 304 stainless steel, 24, 22 or 20 gauge; or copper |
| Finish | Bare stainless, powder coat in any RAL color, or copper |
| Skirt | 3 inches standard, adjustable, with half-inch drip edge |
| Top | X bend cross break, on by default |
| Holes | Round or rectangular, collar 2 inches high standard, storm collar optional, positioned by edge distances |
| Mounting | Pre-drilled skirt holes or top holes, optional |
| Returns | Made to order; not returnable |
Questions people ask
How do I know I need a new chase cover?
Rust streaks down the siding below the chimney, water stains on the ceiling near the fireplace, or a rusted or dished pan when you look from the roof. The original covers on many factory-built fireplaces are thin galvanized steel and rust through in 10 to 15 years. A stainless cover ends the problem for good.
Which gauge should I choose?
24 gauge is the standard and is right for most chases up to about 4 feet on the long side. Choose 22 gauge for larger covers, heavy snow, or a cover that people will step on while sweeping. 20 gauge is the heaviest and is for very large chases and commercial work.
Where exactly do I measure the pipe hole?
Measure the outside of the chimney pipe, not the inside, and enter that as the diameter. Then measure from the outside of the chase to the nearest side of the pipe on all four sides and enter those as the edge distances. The configurator checks that the numbers add up to your length and width, so a mistake shows before you order.
What is the collar for, and do I need a storm collar?
The collar is a short upstand around the hole, 2 inches as standard, that keeps water on the cover from running down the pipe into the chase. A storm collar is the separate cone that sits on the pipe above it and sheds water over the collar. Every chimney pipe should have one; if yours is missing or rusted, add it here.
What are the X bend and the drip edge?
The X bend is a shallow crease pressed across the top from corner to corner. It stiffens the pan and gives water a direction to run instead of pooling in the middle, which is what dishes and rusts a flat cover. The drip edge is a half-inch fold at the bottom of the skirt that throws water clear of the siding. Both are on by default, and we recommend leaving them on.
My chase is not square, or has more than one pipe
Measure each side at both ends and the two diagonals, and enter the largest length and width. For two or three pipes, choose the matching cover type and enter each hole separately; the edge distances place them exactly. If a hole is rectangular, for a masonry flue tile or a square termination, choose Rectangle for that hole.
Skirt mounting holes or top mounting holes?
Skirt holes, for almost everyone: the screws go sideways through the skirt into the chase framing, above the siding, where they cannot leak. Top holes are for a cover that sits on a flat masonry crown and cannot be reached from the side. Every screw through the top needs sealant under its head.
Copper or powder coat?
Copper is made to order and weathers from bright to brown to green over the years; choose it to match copper gutters or valleys. Powder coat goes over the stainless steel and comes in any RAL color, so the cover can match the siding, the roof, or the cap. Bare stainless needs nothing and weathers to a soft grey.
Can I keep my old chimney cap?
Usually, yes. The cap clamps to the chimney pipe, not to the cover. Take it off, fit the new cover, and put the cap back. If the cap is rusted too, this is the moment to replace it.
Can I return it?
No. Every cover is cut to your measurements after you order, so it cannot be returned or exchanged. Measure twice, save the PDF of your configuration, and send us photos if anything looks unusual. We check every order before it goes to the shop.