What Is a Chimney Cricket? Why Your Chicago Home Might Need One

A chimney cricket is a small, peaked, roof-like structure built on the high side of a chimney where it meets the roof. Picture a miniature gable roof or a wedge-shaped tent pressed against the back of the chimney. Its single job is to take water and snow flowing down the slope above and split it into two streams that run cleanly around either side of the chimney, rather than slamming into the flat back wall and pooling there.

The terms chimney cricket and chimney saddle describe the same thing and are used interchangeably by roofers and chimney technicians. You may also hear it called a backer or a diverter. Whatever the name, the principle is identical: redirect water away from the most vulnerable seam on your roof. A cricket is typically framed in wood and sheathed, then covered in the same roofing material as the rest of the roof, or finished in metal flashing for a watertight seal. On larger or custom chimneys, a cricket may be fabricated entirely from soldered sheet metal such as copper or galvanized steel.

Without a cricket, the back of a wide chimney becomes a dam. Water, leaves, pine needles, and snow collect in that pocket, stay wet for days, and work their way under the shingles and flashing. In Chicago, where a single winter can deliver dozens of freeze-thaw cycles, that trapped moisture is exactly what cracks flashing, rots roof decking, and rusts fasteners.

The damage a missing cricket causes rarely shows up overnight. It builds quietly over several Chicago winters until a ceiling stain or a failed chimney inspection finally reveals it. Here is what a properly built cricket prevents:

• Roof and ceiling leaks: Standing water behind the chimney eventually finds the smallest gap in the flashing and travels into the attic, staining ceilings and soaking insulation.
• Flashing failure: Pooled water and ice expansion pry apart the step and counter flashing that seals the chimney to the roof. This is one of the most common sources of chimney leaks in older Chicago homes.
• Wood rot and structural decay: Constant moisture rots the roof decking and framing around the chimney, leading to expensive carpentry on top of the masonry work.
• Masonry deterioration: Water held against brick soaks into the mortar joints. When it freezes, it expands and spalls the brick face, the same process behind many chimney repair calls for crumbling brick across Cook and DuPage counties.
• Ice dams and debris buildup: A flat back wall traps snow and leaves, creating ice dams that back water up under the shingles.

For homeowners in heavy-snow communities like Winnetka, Highland Park, and Arlington Heights, a cricket is not a luxury detail. It is the difference between a chimney that sheds Chicago winters and one that slowly absorbs them.

Building codes do not leave crickets to guesswork. The International Residential Code (IRC R1003.20), which Chicago and its suburbs follow, sets a clear threshold: any chimney wider than 30 inches measured perpendicular to the roof slope must have a cricket or saddle where it intersects the roof. The wider the chimney, the larger the dam it creates, so the code scales the requirement to the width.

There is one practical exception. If the chimney passes through the roof at or very near the ridge, water already sheds to both sides naturally and a cricket may not be required. But the vast majority of Chicago chimneys, especially on the brick bungalows, two-flats, and Victorians common across Oak Park, Berwyn, and the North Side, sit partway down a sloped roof where a wide chimney absolutely needs a cricket.

The required cricket height also depends on roof pitch. A steeper roof needs a taller cricket to divert water effectively. A licensed contractor will size the cricket to both the chimney width and the roof slope, and in Chicago this work typically falls under a roofing or building permit. A reputable company will pull the correct permit when a cricket is added during a re-roof or chimney rebuild.

Whether you have an older home that never had a cricket or one whose cricket has failed, the warning signs are usually visible from the ground or the attic. Watch for:

• Water stains on the ceiling or walls near the chimney chase, especially after a heavy rain or snowmelt.
• A dark, persistently damp streak on the brick directly behind the chimney where it meets the roof.
• Debris piles of leaves and needles collecting on the high side of the chimney that never seem to wash away.
• Rusted or lifting flashing on the back of the chimney.
• Spalling or flaking brick concentrated on the up-slope face, a sign water has been sitting against the masonry. Our article on spalling bricks on your chimney explains how that freeze-thaw damage progresses.
• Ice buildup behind the chimney in winter that lingers long after the rest of the roof has cleared.

If you see any of these, the back of your chimney is holding water it should be shedding. A professional chimney inspection can confirm whether a missing or failed cricket is the cause before the damage spreads to the decking and framing.

A chimney cricket can be built in a few different ways depending on chimney width, roof pitch, and budget. Here is how the common approaches compare:

Regardless of type, the critical detail is the flashing. The cricket must be properly integrated with step flashing along the sides and counter flashing let into the chimney mortar joints. A cricket that looks right but is flashed poorly will still leak. This is why crickets are best installed by a contractor who handles both roofing and chimney repair, rather than treating the two trades separately.

Pricing depends on chimney width, roof pitch and height, material choice, and whether the work is done on its own or bundled with a re-roof or chimney rebuild. The ranges below reflect typical 2026 pricing across the Chicago metro:

The most cost-effective time to add a cricket is during a roof replacement or a chimney rebuild, when crews and access are already in place. If you are weighing larger masonry work, our Chicago chimney rebuild cost breakdown can help you plan the combined project. Adding a cricket as a standalone job is still well worth it when leaks are active, since the repair cost of rotted decking and interior water damage dwarfs the price of the cricket itself.

For a precise quote on your home, call Widen Chicago at (224) 343-1991. We serve Chicago and more than 100 suburbs across Cook, DuPage, and Lake counties.

A cricket is low-maintenance, but it is not maintenance-free. Because it sits at a seam where two slopes meet, it deserves a look during your seasonal roof and chimney checks. Keep the valleys on either side of the cricket clear of leaves and needles so water can run off freely. After major storms or heavy snow, watch for any new staining near the chimney inside the home. And any time you have a chimney sweep or roofer on site, ask them to confirm the cricket flashing is still tight.

Pairing cricket care with broader moisture protection pays off in Chicago. Many homeowners combine a cricket with masonry waterproofing and a quality chimney cap to seal the chimney against water from every direction. Our guide to chimney waterproofing costs in Chicago covers how those measures work together to extend the life of your chimney. If you would rather have a professional assess your roof line, call (224) 343-1991 to schedule an inspection.