By The Roofing Brief Team | Last reviewed: October 2026
A chimney chase cover is the sheet-metal lid over a framed chimney chase, with a collar for the flue pipe. As of October 2026, standard 24-gauge stainless covers cost $264 (12 x 18 in) to $1,161 (54 x 78 in).
Key takeaways
- Rockford Chimney Supply’s standard 304 stainless chase covers price at about $8.80 per inch of length plus width: 30 x 42 in and 36 x 36 in both cost $633 (Rockford standard-size listing, Oct 2026).
- The same listing specifies 24 gauge with 22 or 20 gauge optional, diagonal creases, a 3 inch skirt with drip edge and a 2 inch collar, and a hole 1/2 inch larger than the pipe.
- Rockford says galvanized tops hold water in a low spot until “the metal starts to rust,” staining the siding, and that water may leak inside before rust shows (Rockford chase cover page).
- Factory-built chimneys must be installed and terminated per the maker’s instructions, and decorative shrouds are banned on them unless listed for that system (IRC R1005.1 and R1005.2, 2021 IRC as adopted in New Jersey).
- DuraVent’s DuraTech Chase Top Flashing “encloses the top of a chase while providing ventilation air passage to the chase” (DuraTech brochure DV-DT-BR-001E), so check chase venting before fitting a sealed cover.
Chimney chase cover key numbers at a glance
Seven numbers decide whether a chimney chase cover fits and drains: the measuring tolerance, the 1/4 inch allowance, the hole oversize, the skirt and collar heights, the gauge and the code’s minimum flashing thickness. Each row names the listing, maker document or code section it comes from, all accessed October 2026.
| Figure | Value | Source |
|---|---|---|
| Measure each side to | Nearest 1/8 in, all four sides | Rockford custom stainless listing |
| Allowance added to length and width | 1/4 in | Rockford custom stainless listing |
| Hole size for a round pipe | Pipe outside diameter plus 1/2 in | Rockford standard and custom listings |
| Skirt height | About 3 in, with a 1/2 in drip edge | Rockford custom stainless listing |
| Collar height | 2 to 3 in | Rockford custom stainless listing |
| Standard gauge | 24 ga, with 22 and 20 ga optional | Rockford standard-size listing |
| Code minimum for metal flashing | 0.019 in (No. 26 galvanized sheet) | IRC R903.2.1 |
What is a chimney chase cover, and what does code say about it?
A chase cover is the metal top of the framed box, or chase, that encloses a factory-built metal chimney; Rockford also sells them as lids over brick crowns. The IRC chapters we read (9 and 10) have no chase cover section, so the rules come from R1005.1 (install and terminate per the chimney maker), R1005.2 (listed shrouds only) and R903.2.1 (0.019 inch minimum metal flashing).
The chase is a wall with a roof on it. Its siding and framing are combustible, and the metal chimney inside must be listed: IRC R1005.3 requires Type HT chimneys under UL 103 where solid fuel is burned, and R1005.4 requires UL 127 compliance for chimneys serving factory-built fireplaces. DuraVent’s DuraTech, for example, is listed to UL 103 HT and needs 2 inches of clearance to combustibles (DuraTech Install Guide L923).
The cover itself is flashing, so the general flashing rule applies. R903.2.1 says metal flashing “shall be corrosion resistant with a thickness of not less than 0.019 inch,” equal to No. 26 galvanized sheet (2021 IRC Chapter 9, New Jersey adoption). Gauge numbers run backwards, so the 24, 22 and 20 gauge covers Rockford sells are all heavier than that floor.
Two parts sit on top of the cover. The flue pipe ends in the chimney maker’s listed cap, which DuraTech’s guide installs by pressing it “into the last section of pipe,” and a storm collar seals the gap where the pipe passes through the cover. Masonry flue caps, sizing and mesh rules are covered in our sibling guide to the chimney cap.
Why do chimney chase covers rust and leak?
Rockford traces galvanized chase cover failures to standing water. Its chase cover page says galvanized tops hold water in a low spot, “after a while the metal starts to rust,” rust runs down and stains the siding, and water may enter the chase before the rust is visible. The table pairs each of 6 symptoms with the feature or part that Rockford and DuraVent specify for it.
| What you see | Likely cause | Fix | Source |
|---|---|---|---|
| Orange streaks on the siding below the chase | Galvanized top rusting where water ponds | Replace with 304 stainless or copper | Rockford chase cover page |
| Dished or sagging center, puddles after rain | Flat top with no creases | Cover with diagonal creases “for increased strength and water run-off” | Rockford standard-size listing |
| Water stains on the ceiling or wall beside the chase | Leak through the top before rust shows, or at the pipe collar | Inspect cover, collar seam and storm collar | Rockford chase cover page; DuraTech guide L923 |
| Gap or daylight around the flue pipe | Missing storm collar or failed sealant | Storm collar sized to the pipe OD, sealed with high temperature silicone | DuraTech guide L923, step 13 |
| Rotted trim at the top of the siding | Skirt too short to cover exposed wood | Skirt of about 3 in with a 1/2 in drip edge | Rockford custom stainless listing |
| Animals inside the chase | Unscreened vent openings | Chase air intake with rodent guard | DuraTech brochure |
Galvanized steel protects itself with a zinc coating that is used up over time, and Rockford backs only its stainless and copper covers with lifetime rust warranties; the coating process is explained in our comparison of galvanized vs galvalume roofing. Once the stain reaches the ceiling, tracing it back to the chase rather than the roof is covered in our guide to a water stain on the ceiling.
Galvanized, stainless or copper: which chase cover material?
304 stainless is the default replacement: Rockford makes its standard covers in 304 stainless at 24 gauge and backs them with a lifetime warranty it says transfers to the next homeowner. Copper is a custom order for looks, with options listed up to $1,879.99. Rockford says galvanized covers rust quickly and need frequent replacement, which is why it recommends stainless instead.
| Material | Gauges or sizes offered | Price seen, Oct 2026 | Warranty | Source |
|---|---|---|---|---|
| 304 stainless, standard size | 24 ga (22, 20 optional); 12 x 18 to 54 x 78 in | $264 to $1,161 | Lifetime, transferable | Rockford standard-size listing |
| 304 stainless, custom | 24, 22, 20 ga; to 120 x 60 in (24, 22 ga) or 120 x 48 in (20 ga) | $348.84 to $1,042.77 across listed options | Lifetime against rust, corrosion and defects | Rockford custom stainless listing |
| Copper, custom | 16 x 16 to 96 x 48 in | Options listed to $1,879.99 | Lifetime against rust and defects | Rockford custom copper listing |
| Galvanneal steel | 22 ga; around 15% of the covers HY-C makes (the other 85% are 22 ga 304 stainless) | Not priced | Not stated | HY-C chase cover guide |
| Galvanized steel | Not in Rockford’s chase cover listings | Not priced here | Not stated | Rockford custom stainless listing |
The custom listings show configured prices without size labels, so treat those ranges as the spread of listed configurations, not a size chart. Our guide to the stainless steel roof explains how 304 compares with other grades, and copper’s weathering is covered in our copper roofing guide.
What features should a chimney chase cover have?
Rockford’s listings specify five features: diagonal creases or a cross break so water runs off, a skirt of about 3 inches that covers the top of the siding, a 1/2 inch drip edge that throws water clear, a welded and sealed collar 2 to 3 inches tall, and a storm collar sealing the pipe. Rockford includes the creases and drip edge at no extra charge.
| Feature | Spec | What it does | Source |
|---|---|---|---|
| Diagonal creases (cross break) | Creased top, standard | Adds stiffness and sheds water off the top | Rockford standard-size listing |
| Skirt | About 3 in; HY-C reports 68% of its covers at 3 in, 28% at 4 in, 4% at 2 in | Covers exposed wood and takes the fasteners | Rockford custom stainless listing; HY-C guide |
| Drip edge | 1/2 in on the skirt | Kicks water away from the siding | Rockford custom stainless listing |
| Collar | 2 to 3 in, rolled, spot welded, silicone sealed | Raises the pipe opening above the deck | Rockford custom stainless listing |
| Storm collar | Sized to pipe OD, e.g. 4 in collar fits 3 7/8 to 4 3/8 in pipe | Closes the gap between pipe and collar | Rockford custom stainless listing |
| Seams | Welded and sealed | No lapped joints left open on the top | Rockford standard-size listing |
A chase cover is not the place for a decorative metal shroud around the flue. IRC R1005.2 says decorative shrouds “shall not be installed at the termination of factory-built chimneys” unless they are listed and labeled for that specific chimney system, so a shroud-style cover needs the chimney maker’s listing. A chase wider than 30 inches on the ridge side also needs a cricket under R903.2.2, explained in our chimney cricket install guide.
How do you measure for a chimney chase cover?
Measure all four sides of the chase top to the nearest 1/8 inch, take the longer of each pair, and add 1/4 inch to both length and width. Then measure the pipe’s outside diameter and add 1/2 inch for the hole, and record the distance from the hole’s edge to each side unless the pipe is centered. Rockford’s measuring rules set every figure in these steps.
- Measure both long sides and both short sides of the chase top to the nearest 1/8 in.
- Use the longer long side as the length and the longer short side as the width.
- Add 1/4 in to the length and to the width.
- Measure the flue pipe’s outside diameter and add 1/2 in for the hole; for an oval, square or rectangular clay flue, add 1/2 in to each dimension.
- Measure from the edge of the hole to all four sides, unless the hole is centered.
- Order the storm collar by the pipe’s outside diameter.
Custom covers are made to order and non-returnable, with fabrication of about 1 to 2 weeks for stainless and about 2 weeks for copper, so a measuring error costs the whole cover. Rockford places an off-center hole at no extra charge and will make a cover with no hole, one hole or several. HY-C’s guide reports that 89% of its covers need 1 hole, 9% need 2 and 2% need 3, so count the metal flue pipes first.
How much does a chimney chase cover cost?
As of October 2026, Rockford’s standard-size 24-gauge stainless chase covers run $264 for 12 x 18 inches to $1,161 for 54 x 78 inches, and the price tracks length plus width at about $8.80 per inch. Custom stainless options listed $348.84 to $1,042.77 and copper options reached $1,879.99. Labor is extra.
| Standard size (in) | Area (sq ft) | Price, Oct 2026 | Price per sq ft |
|---|---|---|---|
| 12 x 18 | 1.50 | $264 | $176.00 |
| 24 x 24 | 4.00 | $422 | $105.50 |
| 36 x 36 | 9.00 | $633 | $70.33 |
| 48 x 48 | 16.00 | $844 | $52.75 |
| 54 x 78 | 29.25 | $1,161 | $39.69 |
The pricing pattern is our arithmetic from Rockford’s 59-size table: every listed price divides by length plus width to between $8.78 and $8.80. That is why a 30 x 42 inch cover and a 36 x 36 inch cover both list at $633, and why price per square foot falls from $176.00 to $39.69 as covers get larger.
| Size (in) | Length plus width (in) | Price | Price per inch of length plus width |
|---|---|---|---|
| 12 x 30 | 42 | $369 | $8.79 |
| 21 x 21 | 42 | $369 | $8.79 |
| 30 x 42 | 72 | $633 | $8.79 |
| 36 x 36 | 72 | $633 | $8.79 |
| 48 x 72 | 120 | $1,056 | $8.80 |
The worked example prices a chase that measures 29 3/4 x 41 3/4 inches, which becomes a 30 x 42 inch order after the 1/4 inch allowance. Labor is shown as wages per crew hour at the Bureau of Labor Statistics May 2025 median for roofers, $26.65 an hour (BLS Occupational Outlook Handbook), because no primary source we opened publishes chase cover install hours.
| Line | Amount | Basis |
|---|---|---|
| Chase measured | 29 3/4 x 41 3/4 in | Input |
| Order size | 30 x 42 in | Add 1/4 in to each (Rockford) |
| 304 stainless chase cover, 24 ga | $633.00 | Rockford standard-size listing, Oct 2026 |
| DuraTech storm collar, 5 or 6 in pipe | $35.02 | Rockford storm collar listing, Oct 2026 |
| Materials subtotal | $668.02 | $633.00 + $35.02 |
| Wages per crew hour, 2 roofers | $53.30 | 2 x $26.65 (BLS median, May 2025), before contractor overhead and margin |
Rotted chase framing or sheathing under a leaking galvanized top is carpentry priced separately from the $633 cover, so have the chimney and chase inspected before ordering; see our sibling guide to chimney inspection cost.
How do you install a chimney chase cover?
Installing a chase cover is a roof job in 6 steps: remove the listed chimney cap and old storm collar, lift off the old cover, set the new cover so its skirt laps the siding, fasten through the skirt, then slide the storm collar down and seal it with high temperature silicone before refitting the cap. DuraTech’s guide sets the collar and cap steps.
- Remove the chimney cap from the top pipe section; DuraTech’s guide takes its cap off for cleaning by removing 4 screws.
- Remove the old storm collar and the old cover, and check the top of the chase framing for soft or wet wood.
- Set the new cover over the pipe so the skirt laps the top of the siding on all four sides.
- Fasten through the skirt into the chase sides, which the roughly 3 in skirt is sized to take.
- Slip the storm collar around the pipe, slide it down to the collar and apply high temperature silicone where it meets the chimney (DuraTech step 13).
- Press the chimney cap back into the last section of pipe (DuraTech step 15).
Work on a chase top happens at the roof’s highest point. OSHA’s construction ladder rule, 29 CFR 1926.1053, requires ladder side rails to extend at least 3 ft above the upper landing. Flashing where the chase meets the roof is a separate detail, covered in our guide to step flashing installation.
Which chimney chase cover should you buy?
Start with the chimney maker’s manual, then the size. If the manual lists its own chase top or a chase ventilation part, use it or match its venting. If the chase matches one of Rockford’s 59 standard sizes, a standard 24-gauge stainless cover is the cheapest route; otherwise order custom stainless to the 1/8 inch, or copper where looks decide.
| If your situation is | Do this | Rule behind it |
|---|---|---|
| Chimney manual lists a chase top or chase air intake | Use the listed part, or keep the venting it provides | IRC R1005.1; DuraTech brochure |
| Galvanized top with rust streaks or ponding | Replace with 304 stainless, creased top | Rockford chase cover page and listings |
| Chase within 1/4 in of a standard size | Standard-size stainless, $264 to $1,161 | Rockford standard-size listing |
| Odd size or off-center pipe | Custom stainless, measured to 1/8 in plus 1/4 in | Rockford custom stainless listing |
| Chase longer than 120 in | Spliced custom cover by quote | Rockford custom stainless listing |
| Copper trim or roofing to match | Custom copper, about 2 weeks to fabricate | Rockford custom copper listing |
| Decorative shroud wanted on a factory-built chimney | Only a shroud listed for that chimney system | IRC R1005.2 |
| Chase wider than 30 in on the ridge side | Add a cricket | IRC R903.2.2 |
How we compiled this
We compiled this page in October 2026 from 12 documents: the 2021 IRC chapters 9 and 10 as adopted in New Jersey, DuraVent’s DuraTech install guide and brochure, five Rockford Chimney Supply listings and pages, HY-C’s chase cover guide, the BLS roofer wage page and OSHA’s ladder standard. We did not test or install any cover; the price-per-inch and per-square-foot figures are our arithmetic from Rockford’s published size table.
Frequently asked questions
What’s a chimney chase cover?
It is the metal lid that closes the top of the framed box around a factory-built chimney, which HY-C’s guide calls a “pan-like metal sheet with a hole” for each flue pipe. Rockford’s standard covers add diagonal creases to shed water and a 3 inch skirt with a drip edge over the siding. The flue pipe still needs its own listed cap.
How much does it cost to replace a chimney chase cover?
As of October 2026, Rockford Chimney Supply lists standard 24-gauge 304 stainless covers at $264 (12 x 18 in) to $1,161 (54 x 78 in), about $8.80 per inch of length plus width, and a 5 or 6 inch DuraTech storm collar at $35.02. No primary source we opened publishes install labor; BLS puts the median roofer wage at $26.65 an hour (May 2025).
What is the difference between a chimney cap and a chimney chase cover?
A chase cover is the flat sheet-metal lid over the whole framed chase; a chimney cap is the small hood and screen on the flue outlet, which on a factory-built chimney must be the maker’s listed cap under IRC R1005.1. HY-C’s guide notes that on a masonry chimney the crown does the chase cover’s job. A chase with a metal flue pipe needs both.
Where can I buy a chimney chase cover?
Chimney supply retailers sell them made to order. Rockford Chimney Supply lists 59 standard 304 stainless sizes plus custom stainless and copper covers, fabricated in about 1 to 2 weeks, and HY-C points buyers to online shops and dealers. Custom covers are non-returnable, so measure all four sides to 1/8 inch and add 1/4 inch before ordering.
What is the best material for a chimney chase cover?
For a replacement, 304 stainless steel, which Rockford uses for its standard covers and backs with a transferable lifetime warranty; HY-C reports that 85% of the covers it makes are 22-gauge 304 stainless and 15% are 22-gauge galvanneal. Copper is the custom option chosen for looks, listed up to $1,879.99. Rockford says galvanized covers rust quickly.
How long does a chimney chase cover last?
No maker document we opened publishes a service life in years. What is published is the warranty: Rockford gives its 304 stainless covers a lifetime warranty against rust, corrosion and defects and its copper covers a lifetime warranty against rust and defects. Rockford describes galvanized as the material that rusts and needs frequent replacement.
Can I install a chimney chase cover myself?
The fitting is simple: about 3 inches of skirt takes the fasteners, a storm collar sealed with high temperature silicone closes the pipe gap, and the cap presses back into the pipe (DuraTech guide steps 13 and 15). The hazard is the roof. OSHA 1926.1053 requires ladder rails 3 ft above the landing, and covers are non-returnable if mismeasured.
Can you put a chase cover on a brick chimney?
Yes. Rockford describes its covers as an external top for “a pre-fab chimney or a brick chimney,” fitting over a masonry crown like a lid, with the collar matched to a square or rectangular clay flue tile so a single-flue cap can still mount. On masonry, IRC R1003.9.1 still requires the crown itself to be sloped with a drip edge.
Sources
- Rockford Chimney Supply, Chimney Chase Cover: Standard Size (304 stainless, 59 sizes), accessed Oct 2026
- Rockford Chimney Supply, Stainless Steel Chase Covers (custom), accessed Oct 2026
- Rockford Chimney Supply, Copper Chimney Chase Covers (custom), accessed Oct 2026
- Rockford Chimney Supply, Chimney Chase Covers overview, accessed Oct 2026
- Rockford Chimney Supply, DuraTech Storm Collar 5 to 8 in ($35.02 to $38.71), accessed Oct 2026
- HY-C, A Comprehensive Guide to Chimney Chase Covers (blog guide with HY-C order data), accessed Oct 2026
- 2021 International Residential Code, Chapter 10 (R1003, R1005), New Jersey adoption (UpCodes), accessed Oct 2026
- 2021 International Residential Code, Chapter 9 (R903.2), New Jersey adoption (UpCodes), accessed Oct 2026
- DuraVent DuraTech Install Guide L923, accessed Oct 2026
- DuraVent DuraTech brochure DV-DT-BR-001E (06-24), accessed Oct 2026
- U.S. Bureau of Labor Statistics, Occupational Outlook Handbook: Roofers, accessed Oct 2026
- OSHA 29 CFR 1926.1053, Ladders, accessed Oct 2026