Chimney Crickets

Chimney Cricket Moisture intrusion around chimney penetrations is a common issue. Large chimneys on a roof can collect snow, water, and debris on their uphill side. Water pooling at a chimney can deteriorate the roof covering material, flashing, and the chimney itself. Prolonged moisture buildup can eventually cause rook leaks and even structural damage in severe situations. Luckily chimney crickets, when properly installed, can significantly decrease the likelihood of moisture and debris buildup around chimneys.

A chimney cricket or “chimney saddle” is a small structure with two valleys and one ridge that is installed against the uphill side of a chimney.  The purpose of a cricket is to divert roof water runoff and debris away from the chimney where it could cause leaks and damage. In 2012, the IBC (International Building Code) began requiring that chimney crickets be installed for chimneys that are 30 inches wide or larger.

A common cricket construction will begin with removing the roof covering materials on the uphill side of the chimney. A wood frame that includes two valleys on either side of the cricket ridge is then installed. Next, the cricket structure will be flashed into the chimney side wall and a water-proof membrane is installed over the sheathed cricket frame. Finally, the cricket will have a roof covering material installed that matches the rest of the roof. Some crickets are premade from aluminum, steel, or copper. These preformed metal crickets are installed over the wood frame in place of a matching roof covering material.

Lack of a Chimney Cricket Many older homes have large brick chimneys that do not have crickets installed. Because roofs are often dangerous for a homeowner to access, it is common to find excessive amounts of debris accumulated behind chimneys. Home inspectors frequently find staining and wood sheathing deterioration around chimney penetrations during our inspection of the attic space. Debris and the associated moisture pooling on the back side of the chimney can be a contribution factor to these conditions.

It is recommended that chimneys 30 inches or wider have crickets installed regardless of the age of the home. Crickets should be installed by qualified roofing contractors. Improperly installed chimney crickets can potentially make moisture issues worse. If you have a moderate to large sized chimney for your home, we recommend that it be inspected to determine the presence or need for a cricket installation.