What Is Chimney Cricket?
A chimney interrupts the flow of everything draining down the slope above it. On its uphill side, water and debris decelerate and pile against the vertical masonry — a dam that holds wet leaves against flashing year-round and, in storms, pools water above the flashing's height. A cricket solves the geometry: a miniature ridged roof, framed and flashed (or formed entirely from metal on smaller chimneys), that splits the flow into two streams passing either side. The IRC requires one behind chimneys wider than 30 inches measured across the slope. Failure modes are absence — many older roofs simply never had one, and the leak behind the chimney gets endlessly re-caulked instead — plus seams opening on metal crickets and debris still snagging on flat-pitched ones. Homeowners can check from the ground or attic: a wide chimney with roofing dead-ending flat against its back is the finding. Retrofit during re-roofing is straightforward; standalone retrofit means opening that roof section.
Important Distinction
Note: Code (IRC) requires a cricket when the chimney is wider than 30 inches across the slope; narrower chimneys use a back pan flashing instead. A wide chimney with no cricket leaks behind itself by design, and no amount of re-caulking fixes the geometry.
Also Known As
These are the search terms and phrases that commonly refer to this topic, so you can find it however you describe it.
How Chimney Cricket Relates to Other Topics
Flashing handles the sides and downhill face of a chimney, but the uphill side collects water and debris; that is the cricket's job - a small peaked diverter that splits the flow around the masonry.
Related To Chimney Cricket
Efflorescence concentrated on the uphill face of a chimney is water telling you where it dams: that face takes the roof's runoff head-on, which is the same reason wide chimneys get crickets built behind them.
Questions about Chimney Cricket?
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