A chimney (see our chimney flashing installation detail) cricket is a small framed peak built on the uphill side of a chimney to divert water and debris around the chimney instead of letting it pool against the upper face. IRC 2024 Section R1003.20 requires a cricket on any chimney that measures more than 30 inches wide on the uphill side, measured parallel to the ridge. The install cost in 2026 runs from $800 for a small cricket added during a reroof up to $2,200 for a tall cricket built as a standalone retrofit with custom flashing. Without one, a wide chimney will leak no matter how good the flashing is.
The short version
- Code threshold: any chimney more than 30 inches wide on the uphill side needs a cricket per IRC 2024 R1003.20.
- The cricket is a framed mini-roof with two sloping planes that shed water around the chimney to either side.
- Slope target: cricket slope should match or exceed the main roof slope, with a minimum of 4:12.
- Install cost 2026: $800 to $2,200 depending on chimney width, cricket height, and metal choice.
- Required materials: 2×4 or 2×6 framing, 1/2-inch plywood, ice and water shield, step and head flashing, counter flashing.
- The single most common build mistake: framing the cricket too short or too shallow so it does not actually shed water past the chimney corners.
What a chimney cricket actually does
A chimney sitting on a sloped roof acts like a small dam. Water flowing down the roof field hits the uphill face, fans out sideways, and either flows around the chimney corners or pools against the back face. Debris (leaves, twigs, asphalt granules from aging shingles) collects in that pooled water and creates a wet wedge against the brick. Over time, the saturated debris breaks down flashing sealant, drives water sideways through reglet joints, and starts chimney flashing leaks that no amount of caulk will fix.
A cricket (see our roof cricket design and install (broader)) eliminates the dam. The framed peak takes the water flowing down the roof and splits it into two streams that bypass the chimney corners by 6 to 12 inches. Debris cannot accumulate because there is no flat catchment. Sealant lasts longer because it stays dry. A correctly built cricket extends chimney flashing service life by 10 to 15 years.
When code requires a cricket
The 30-inch threshold has been in the International Residential Code since the 2009 edition and is carried forward in IRC 2024. The measurement is straightforward: stand uphill of the chimney, measure the chimney width parallel to the ridge. If that dimension exceeds 30 inches, a cricket is required.
| Chimney uphill width | Cricket required? | Typical cricket height |
|---|---|---|
| Under 24 inches | No (saddle optional) | N/A |
| 24 to 30 inches | Recommended, not required | 4 to 6 inches |
| 30 to 48 inches | Required (IRC R1003.20) | 6 to 10 inches |
| 48 to 72 inches | Required, larger frame | 10 to 16 inches |
| Over 72 inches | Required, engineered detail | 16 inches and up |
Some jurisdictions follow IBC (commercial code) instead of IRC for chimneys on multi-family or mixed-use buildings. IBC 2024 uses the same 30-inch threshold. Local amendments occasionally tighten the rule, especially in high-snow regions where as little as 24 inches of width may trigger the requirement. Pull your local amendment before specifying.
Cricket geometry: how to size it
The cricket has three controlling dimensions: width (how wide it spans behind the chimney), length (how far it extends uphill from the back face of the chimney), and slope.
Width
The cricket should be at least as wide as the chimney itself, ideally 6 to 12 inches wider on each side so water exits past the rear chimney corners with clearance. A 36-inch-wide chimney calls for a cricket 48 to 60 inches wide at the base.
Length
The classic rule of thumb sets cricket length (uphill projection) equal to half the chimney width. A 36-inch chimney gets an 18-inch cricket. In practice, this minimum produces a cricket that is too shallow to drain well on low-slope roofs. Better practice: set cricket length so cricket slope matches main roof slope, never less than 4:12. On a 4:12 roof, an 18-inch-long cricket gives 6 inches of height, which is the practical minimum.
Slope
Minimum cricket slope is 4:12 (33%). Below this, water sheets rather than channels and debris collects in the valleys. On steep roofs (10:12 and up), match the main roof slope so the cricket reads visually as part of the roof, not an afterthought.
Worked example
A 42-inch wide chimney on an 8:12 main roof.
- Cricket width at base: 42 + 12 + 12 = 66 inches
- Cricket length uphill: half of chimney width = 21 inches
- Cricket height to match 8:12 slope: 21 x 8/12 = 14 inches at the chimney face
- Cricket falls to 0 at the uphill point
Materials list for a typical 36-inch chimney cricket
| Material | Spec | Quantity | Notes |
|---|---|---|---|
| Center ridge board | 2×6 SPF | 1 piece, 24 inches | Cut to cricket length |
| Hip rafters | 2×4 SPF | 2 pieces, 30 inches | From ridge to chimney back corners |
| Sheathing | 1/2-inch CDX plywood | 1 sheet (use scrap) | Two triangular panels |
| Underlayment | Ice and water shield | 1 roll partial | Full coverage, lapped onto chimney |
| Step flashing | Aluminum 4×6 inch | 8 to 10 pieces | One per shingle course up cricket sides |
| Head flashing | Aluminum, fabricated | 1 piece | Spans uphill cricket peak |
| Counter flashing | Aluminum or copper | Fabricated to fit | Saw-cut reglet bedded |
| Sealant | Polyurethane | 2 tubes | NPC Solar Seal 900 or similar |
| Roofing nails | 1.5-inch galvanized | 1 lb | Deck nailing only |
Total materials cost for a 36-inch cricket: $90 to $180 depending on metal choice. The rest of the install cost is labor.
Step by step: how to build a chimney cricket
This is the construction sequence a competent roofing crew will follow on a new build or full reroof retrofit. Skipping or reordering steps creates leak points.
Step 1: layout
Snap chalk lines on the roof deck for the cricket footprint: a triangle with the base running across the back of the chimney and the apex pointing uphill at the calculated length. Verify the lines are perpendicular to the chimney face and the apex is centered.
Step 2: cut and set the ridge board
Cut a 2×6 to cricket length. Set it on edge running from the back face of the chimney to the uphill apex. Toe-nail to the deck on the apex end. The chimney end of the ridge board butts against the brick. Trim the chimney end to match the slope of the main roof so it sits flat against the deck.
Step 3: cut and set hip rafters
Cut two 2×4 hip rafters running from the ridge board down to the back corners of the chimney. The bird’s mouth at the corner end should sit flush on the deck. Toe-nail each rafter to the ridge board and to the deck. Verify the hip lines are straight from corner to apex.
Step 4: sheath the cricket
Cut two triangular plywood panels from 1/2-inch CDX. Each panel covers one slope of the cricket. Nail to the ridge, hip rafters, and deck with 8d nails at 6 inches on edges and 12 inches in the field. Sheathing should butt tight against the brick face at the chimney end and end flush with the deck at the apex.
Step 5: ice and water shield
This is the most critical step and the one most often skipped. Apply self-adhered ice and water shield (Grace Ice and Water Shield, Henry Blueskin, GAF StormGuard, or equivalent) to cover the entire cricket sheathing, lapping at least 6 inches onto the main roof deck downhill, 4 inches up the chimney face on all sides, and extending past the cricket apex onto the deck above by at least 12 inches. See ice and water shield for membrane specs and application detail.
Step 6: install apron flashing across the back face of the chimney
This is the metal that catches the divided water streams coming off the two cricket faces and routes them around the chimney corners. Hem the lower edge to prevent capillary creep. Lap onto each cricket face by at least 4 inches.
Step 7: install step flashing up the cricket sides
Each shingle course up the cricket side gets one piece of step flashing, lapped 2 inches over the piece below, nailed only to the deck and only on the high side. Same detail as standard sidewall step flashing installation. The flashing turns up 4 inches onto the brick.
Step 8: install head flashing at the cricket apex
At the uphill apex, a head flashing piece spans across the peak of the cricket and runs up under the shingles above. Lap onto the membrane below.
Step 9: shingle the cricket
Shingles installed up the cricket faces in matched courses, woven into the main roof shingles at the cricket base. Cut shingles tight along the chimney face. Hand-seal all cut edges with asphalt sealant.
Step 10: counter flashing
Saw-cut a reglet groove in the chimney face at 1.5 inches depth along the cricket sides and apex line. Fabricate counter flashing to fold into the reglet and turn down over the step flashing. Bed in polyurethane sealant. See counter flashing for the install detail.
Cricket install cost 2026
| Project type | Chimney size | Cost | Time on site |
|---|---|---|---|
| Cricket added during new install | 30-42 inches wide | $800-$1,200 | 4-6 hours |
| Cricket added during full reroof | 30-42 inches wide | $700-$1,000 | 4-6 hours |
| Retrofit cricket (existing roof) | 30-42 inches wide | $1,200-$1,800 | 6-8 hours |
| Tall cricket (over 48 inches wide) | 48-72 inches wide | $1,500-$2,500 | 8-10 hours |
| Copper cricket with custom flashing | Any size | $2,200-$4,000 | 1-2 days |
Retrofit installs cost more because the existing shingles around the chimney have to come up, the deck has to be exposed, and matching shingles to the existing field is harder. If your chimney needs a cricket and your roof is over 15 years old, evaluate doing it as part of a full reroof rather than a stand-alone retrofit. See roof repair cost guide for broader context on bundling repairs.
Three common build mistakes that cause leaks
Mistake 1: cricket too short
Builders often install a cricket at the minimum size that satisfies the code letter but produces a slope that does not actually drain. A 4-inch-tall cricket on a 6:12 roof reads on inspection but holds water against the chimney. Always match cricket slope to main roof slope or set 4:12 minimum, whichever is steeper.
Mistake 2: no membrane wrap
Building a cricket with felt underlayment instead of self-adhered ice and water shield is a common shortcut. The cricket valleys see concentrated water flow and ice accumulation in northern climates. Felt fails in those zones. Ice and water shield is the only acceptable underlayment for a cricket.
Mistake 3: caulking instead of cutting a reglet
The counter flashing has to be bedded into a saw-cut reglet groove in the masonry. Turning the metal up against the brick and caulking the top edge to the face works for about 2 years. Then it leaks. Always insist on a saw-cut reglet for counter flashing on a cricket.
Alternatives to a true framed cricket
Two alternatives show up on smaller chimneys where a full framed cricket is overkill.
Built-up roofing cricket
Instead of framing, the roofer builds up a cricket shape using stacked layers of self-adhered membrane and tapered insulation board. Works on low-slope or flat roofs. Not appropriate on shingle roofs at residential scale.
Pre-formed metal saddle
For chimneys at the 24 to 30-inch threshold where a full framed cricket is not required, pre-formed copper or aluminum saddles can be ordered to size. These are folded metal triangles that sit on top of the deck without framing. Lifetime Tool makes a residential pre-formed saddle in stock chimney widths. Effective but limited in scale. See our roof saddle installation guide for the pre-formed detail.
Can you build a cricket yourself?
If you are comfortable on a steep-slope roof, can read framing layouts, and have done at least one full shingle install, a small cricket on an accessible roof is within reach. The framing and sheathing are basic carpentry. The membrane work requires care but is forgiving. The metal work is where DIY attempts go wrong: fabricating step and counter flashing without a metal brake, cutting a clean reglet with a grinder, and bedding sealant cleanly are all skills that take practice.
Realistic DIY scope: frame and sheath the cricket, install ice and water shield, shingle the cricket faces. Bring in a sheet metal pro for the flashing work. Total saved cost: $300 to $600 versus a full pro job. Total saved hours: zero (you will spend the same time you would have paid for).
Cricket vs no cricket: what happens long term
A 36-inch chimney without a cricket on an 8:12 roof in a northern climate will typically:
- Show flashing sealant failure at the back face within 5 to 8 years
- Develop a noticeable leak inside within 8 to 12 years
- Require full reflash within 15 years
- Show masonry deterioration on the back face within 15 to 20 years
The same chimney with a correctly built cricket typically:
- Holds flashing seal for 15 to 25 years
- Does not develop the back-face leak pattern at all
- Reflash interval matches the roof life (25 to 40 years)
- Masonry stays sound, requiring only periodic crown sealing
The economics are not even close. A $1,200 cricket prevents $4,000 to $8,000 in cumulative leak repairs, interior damage, and accelerated chimney deterioration over 20 years.
FAQ
Does every chimney need a cricket?
No. IRC 2024 requires crickets only on chimneys wider than 30 inches on the uphill side. A typical 16×16 single-flue chimney does not need one. A wider double-flue or fireplace chimney does.
Can a cricket be added without tearing off the roof?
Yes, but it costs more. The roofer will pull shingles in the cricket footprint plus a 24-inch perimeter to integrate the new membrane and step flashing into the existing field. Matching shingles to a roof more than 5 years old is the main challenge.
What slope should a cricket be?
Match the main roof slope, with a 4:12 minimum. Crickets shallower than 4:12 do not drain reliably and collect debris.
Is a cricket the same as a saddle?
The terms are used interchangeably in residential roofing. Some pros reserve “saddle” for pre-formed metal pieces and “cricket” for framed structures. There is no formal distinction.
Should I add a cricket if my chimney is exactly 30 inches wide?
Code requires a cricket only when width exceeds 30 inches. At exactly 30 inches you are not required but you are at the threshold where leak patterns start to appear. If your roof is steep (8:12 or more) and your climate is northern, install a cricket anyway. The marginal cost is small and the benefit is real.
Bottom line
The chimney cricket is the single highest-value 1,200-dollar upgrade you can make on a roof with a wide chimney. It is required by code at 30 inches and beyond, it solves a leak problem that flashing alone cannot fix, and it extends chimney service life by 10 to 15 years. Build it during a reroof if possible, because the labor overlap drops the cost by 30%. Insist on a properly framed slope, full ice and water shield wrap, and saw-cut reglet counter flashing. If your roofer wants to skip any of those three, find a different roofer. For broader flashing context, see what is flashing on a roof and roof flashing.