Short answer: a cricket is a small peaked structure built behind a chimney or other wide roof penetration to divert water around it instead of letting it pool against the upslope side. Chimneys wider than about 30 inches generally need one.
The problem it solves
A chimney interrupts the flow of water down a roof. On the upslope side, water, leaves and debris collect against the masonry. Without somewhere to go, that water sits, works into the flashing and eventually into the structure.
A cricket is a miniature roof, peaked in the middle, that splits the flow and sends it around both sides. It is simple, it is cheap when built with the roof, and it prevents one of the most expensive leak patterns there is.
When one is required
The widely used threshold is a chimney wider than 30 inches measured across the slope. Local code governs, and your building department is the authority for your address.
What we can tell you from experience is that plenty of Hill Country homes have wide masonry chimneys and no cricket, because it was skipped during the original build or lost during a previous re-roof.
What happens without one
- Debris packs against the chimney and holds moisture there permanently
- Flashing fails faster because it is constantly wet
- Water works into the masonry, then freezes and expands in a cold snap
- The decking behind the chimney rots, often discovered only at tear-off
- Ceiling staining appears near the chimney and nobody can find the source
Where else crickets apply
Any wide penetration can need one. Skylights, large curbs and wide mechanical units on low slope roofs all benefit from the same principle, which is giving water a path around rather than a pocket to sit in.
Adding one
The time to build a cricket is during a roof replacement, when the chimney flashing is being rebuilt anyway. Adding one later means opening the roof behind the chimney specifically, which costs more for the same result.
If you are getting quotes and your chimney is wide, ask directly whether a cricket is included. If a contractor does not know what you are asking about, that tells you something.
Check your chimney
From the ground, look at the upslope side. If you can see debris piled against the masonry after a rain, there is nowhere for water to go. That is worth a closer look.
Our chimney flashing guide covers the rest of the chimney water story. Book a free inspection or call (210) 245-4125.
