The International Residential Code (IRC R1003.20) requires a chimney cricket — a small roof diverter behind the chimney — when the chimney is wider than 30 inches measured along the uphill side. Without one, rain sheets hit the back of the chimney and pool; debris builds up in the same spot and dams further water; over years, the deck behind the chimney rots and the roof fails at the most expensive place to repair.
What Is a Chimney Cricket?
A chimney cricket (sometimes called a saddle) is a small, peaked structure built onto the roof on the uphill side of a chimney. Its job is to divert water and debris around the chimney rather than letting it collect against the back wall.
A cricket has:
- Two sloped planes that meet at a ridge running perpendicular to the roof’s main slope
- A flashing system that ties into both the roof and the chimney
- A drainage path that directs water to the sides of the chimney, not into the valley behind it
Done right, you barely notice it. Done wrong or skipped entirely, it becomes the single most common source of chimney-related leaks.
When Does Code Require a Cricket?
Per IRC R1003.20 (and referenced in Georgia’s adopted code):
| Chimney Width (uphill side) | Cricket Required? |
|---|---|
| 30 inches or less | No (optional) |
| Wider than 30 inches | Yes |
The IRC R1003.20 language: “Crickets shall be installed on the ridge side of chimneys greater than 30 inches wide measured perpendicular to the slope.” See the 2024 IRC R1003 chimney requirements for the exact code text.
Important caveats:
- Measurement is along the uphill (high side) face of the chimney, not around it.
- Any chimney, regardless of width, benefits from a cricket if the roof slope is shallow or the chimney sits in a location that catches debris.
- Local jurisdictions can enforce stricter interpretations. Gwinnett County follows the IRC baseline.
What Happens Without a Cricket on a Wide Chimney?
The failure sequence, roughly in order:
- Debris dam. Leaves, twigs, and pine needles catch behind the chimney within the first year. Nothing clears them.
- Water pooling. After every rain, water pools against the back chimney flashing for hours instead of minutes.
- Flashing degradation. Prolonged contact with standing water breaks down sealant and corrodes step flashing from the top edge down.
- Leaks at the attic ceiling. The first visible symptom is usually a stain on the ceiling directly below the chimney.
- Deck rot. OSB or plywood behind the chimney swells, delaminates, and eventually loses nail-holding strength.
- Shingle failure. Rotted deck won’t hold shingles down; the area around the chimney starts to look wavy or bubbled.
- Rafter and framing damage. If caught late, the rafters behind the chimney can need sister-framing.
What starts as a missed 30-dollar diverter becomes a 3,000-5,000 dollar chimney rebuild with interior drywall and insulation replacement.
Specific Failure Patterns We See in Sugar Hill
- Debris dams during fall. Mature oak trees in older Sugar Hill neighborhoods drop a continuous layer of leaves October through December. Chimneys without crickets get buried on the uphill side.
- Ice damage (rare but real). Sugar Hill gets occasional hard freezes with precipitation. Without a cricket, pooled water behind a chimney can freeze into an ice dam, pushing water up under shingles.
- Post-remodel chimney widening. Homeowners occasionally reface or widen a chimney during a remodel without adding a cricket. If the new width crosses 30 inches, the cricket becomes required.
- Old chimneys, new roofs. During re-roofs, some contractors skip the cricket to save a day of labor. Always ask.
How Much Does a Cricket Cost to Add?
For most existing chimneys, adding a cricket to an already-installed roof runs 400-900 dollars depending on size and flashing complexity. The work involves:
- Framing the cricket structure with dimensional lumber and a deck skin
- Installing ice-and-water shield across the entire cricket
- New step flashing tied into both the chimney and the roof
- Counter-flashing or a reglet cut into the chimney masonry
- Matching shingles integrated into the surrounding field
When done during a full roof replacement, the incremental cost is lower — often 250-500 dollars — because the flashing and shingles are already being replaced.
Weighed against the cost of rot repair after years of water intrusion (2,000-5,000+ dollars for structural repair plus interior finish work), a cricket is one of the best ROI items on a roof.
When Can You Skip the Cricket?
- Chimney is 30 inches or narrower on the uphill side — code doesn’t require it.
- Chimney is at the ridge itself — no uphill water flow to divert.
- Chimney is on a very steep slope and water sheets off fast enough that pooling is not a concern — still a judgment call, and most roofers install one anyway on wider chimneys.
What to Ask Your Roofer
During any re-roof or chimney-adjacent repair, ask these five questions:
- “How wide is the chimney on the uphill side?”
- “If it’s over 30 inches, is a cricket in the scope?”
- “Will the cricket use ice-and-water shield underlayment?”
- “What flashing material — galvanized, aluminum, or copper?”
- “Will counter-flashing be reglet-cut into the masonry or surface-mounted?”
A contractor who answers these cleanly is someone who takes the detail work seriously. A contractor who dismisses the question or says “we never do that around here” should be crossed off the list.
Related Services
If your chimney is showing stains, loose flashing, or debris accumulation, a chimney-and-flashing inspection is worth scheduling before the next storm season. See our chimney repair service and roof inspection service for what’s covered in a walk-around.
Call for a Free Chimney Inspection
Not sure whether your chimney has a cricket or whether it needs one? Call (470) 888-0030 to schedule a free inspection.