A cricket is a small raised section of roof, sloped on two sides, built to divert water around an obstacle such as a chimney or rooftop unit and toward a drain. Roofing guidance notes that crickets upslope of equipment, and saddles along low points between drains, reduce localized ponding. A cricket helps with a local water problem. It does not fix a roof with no slope or failed drains.
A flat roof cricket is a small, sloped section built into the roof to push water around something that would otherwise block it. Think of a little ridge, like a miniature roof, placed behind a chimney, a rooftop unit or another obstruction so water splits and runs to either side instead of stopping behind it.
What does a cricket do on a flat roof?
Water on a flat roof moves to drains, scuppers or gutters only if the surface slopes toward them. An obstacle on the roof blocks that path. Water arrives at the upslope side, stops, and sits there. That is the classic place for a pond.
The Asphalt Roofing Manufacturers Association says crickets upslope of rooftop equipment reduce localized ponding, and that saddles along the low points between drains do the same job (ARMA). Ponding means water that remains on a low-slope roof 48 hours or longer (ARMA). A cricket changes the shape of the roof at that spot so water has somewhere to go.
Crickets and saddles are usually made from tapered insulation, which is one of the ways the NRCA Roofing Manual, as quoted by ARMA, says positive slope is built into a roof (ARMA). That means a cricket is normally part of the roof system, covered with the same membrane as the rest, not something stuck on top.
Where do you see crickets?
- Behind a chimney, where water would otherwise stop against the masonry
- Upslope of a rooftop unit or a curb
- Along the low line between two drains, where the roof forms a shallow valley
- Beside a skylight or hatch on a roof that ponds
On some pitched roofs the same word is used for a small peaked diverter behind a chimney. The idea is the same.
Do you need a cricket?
Not every flat roof does. If water clears on its own within 48 hours and the roof drains, you do not need one. You may need one if you see the same pond again and again behind a chimney, a unit or along a line between drains. We cover why this happens in flat roof drainage and ponding water, and a cricket is one of the fixes on the list.
What a cricket does not do:
- It does not give slope to a roof built dead flat
- It does not unblock a drain
- It does not repair a membrane that has already been damaged by standing water
- It is not a pile of sealant or a patch. If it is not built to slope, it is not a cricket
On older flat roofs with a chimney in the middle, the pond behind it is one of the most common things we find. It is usually a combination of the obstruction and a drain that is partly blocked. Fixing only one of the two leaves the other.
What about permits and who builds it?
Adding a cricket changes the roof system, so treat it as roof work. The City says any work on low-slope roofs generally needs a permit (City of Chicago), so ask the Department of Buildings. Roofing work for hire in Illinois requires a licensed roofing contractor (Illinois law). If your roof leaks as well as ponds, read why Chicago flat roofs leak.
Our roofing crew can tell you whether a cricket, a new drain or a bigger slope change will fix your pond. The Chicago roofing guide covers the rest of the flat roof.
Common questions
A cricket diverts water around an obstacle, such as a chimney or rooftop unit, so it flows toward a drain instead of stopping behind it. It reduces ponding in that spot.
On a flat roof it is typically built from tapered insulation and covered with the same membrane as the rest of the roof. Tapered insulation is one of the ways positive slope is built into a low-slope roof.
No. A cricket handles local ponding at an obstacle or low line. If the whole roof has too little slope or the drains are in the wrong place, the fix is bigger. A roofer can tell you which applies.
Sources
- Asphalt Roofing Manufacturers Association: Ponding Water Basics
- City of Chicago: Guide to Building Permits: What Types of Work Do Not Require a Building Permit?
- Illinois General Assembly: Roofing Industry Licensing Act, 225 ILCS 335/9
Facts last checked: October 7, 2026.
This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.