What Is a Chimney Cricket, and Why Does Your Inspector Want One?
Most buyers have never heard the term. A chimney cricket is a small peaked roof structure with a specific job: keeping water from pooling against the back of a wide chimney. When it is missing, water has been finding another way in.
What It Is
A chimney cricket, also called a chimney saddle, is a small peaked structure built on the upslope side of a chimney where it meets the roof surface. Picture a tiny pitched roof, the same width as the chimney, sitting directly behind it. Its ridge runs perpendicular to the main roof slope, and its two sides angle down and away from the chimney face, directing water around the chimney rather than letting it collect behind it.
Without a cricket, the angle where the back of the chimney meets the roof creates a valley, a low point where water naturally accumulates during rain. Leaves, pine needles, and debris also collect in this same pocket. The flashing at the back of the chimney sits under constant moisture pressure every time it rains.
Current building standards require a cricket on any chimney wider than 30 inches measured perpendicular to the roof slope. Many older homes, and some not-so-old ones, were built without one, either because the standard did not apply at the time of construction or because it was simply skipped.
Why It Matters
The back of a chimney is one of the more vulnerable points on any roof. Flashing in this location has to manage water coming from above (down the roof slope) and water that wants to work under the flashing from the pocket that forms behind the chimney. A properly installed cricket eliminates that pocket. Without one, the flashing has to do all the work alone, and over time, it typically loses that battle.
Water that gets past the back flashing enters the roof system at the chimney base. From there it follows the path of least resistance, which usually means saturating the roof decking around the chimney, traveling down the rafters, and eventually showing up as water staining on the ceiling below or as moisture in the attic framing near the chimney.
By the time a ceiling stain appears, the leak has been underway for a while. Roof decking that stays wet deteriorates and eventually needs replacement. Framing members adjacent to the chimney can develop rot if the moisture exposure is prolonged.
In the Portland metro and SW Washington, where sustained rain is the norm for half the year, the cumulative effect of rain season after rain season without a cricket adds up faster than it would in a drier climate. This is not a finding to note and revisit later.
How Common Is This?
Common on homes built before the current standard was widely enforced, and occasionally on newer homes where it was overlooked. Russ documents missing chimney crickets regularly across the Portland metro and SW Washington on homes with wide masonry chimneys, particularly older homes in established neighborhoods where the chimney was built to original code standards that predated the cricket requirement.
What Correction Looks Like
Installing a chimney cricket is carpentry and roofing work combined. A qualified roofing contractor builds the cricket frame, typically from dimensional lumber, on the roof surface behind the chimney. The cricket is then sheathed, waterproofed with appropriate membrane, flashed into both the chimney sides and the surrounding shingles, and finished to match the existing roof surface.
The flashing integration is the detail that matters most. A cricket that sheds water correctly but is poorly flashed at its edges still allows water to find a path. A roofing contractor with chimney experience knows how the step flashing, counter-flashing, and cricket flashing all need to overlap and seal against each other.
At the same time, the contractor should assess the condition of the existing back flashing. If flashing that has been under sustained moisture pressure for years shows signs of deterioration, it should be replaced as part of the same scope, not left in place behind a new cricket.
Typical cost in the Portland metro and SW Washington: $500 to $2,000, depending on chimney width, roof pitch, access, and whether any existing flashing or decking needs to be replaced. A wider chimney needs a larger cricket. A steeper roof adds labor.
Chimney Cricket FAQ
