What is a roof cricket?

What it is

Water running down a sloped roof stops when it meets the flat back of a chimney. Without help it pools there, carries leaves and grit into the corner, sits against the flashing and, in winter, freezes. A cricket is a miniature gable — two small sloped planes meeting at a ridge that runs from the chimney back up to the main roof — framed, sheathed, flashed and covered with the same materials as the roof. It turns the pooling joint into two short valleys that drain to either side of the chimney.

The model code makes it mandatory for larger chimneys. The IRC, Section R1003.20 requires a cricket where the chimney's dimension parallel to the ridge is more than 30 inches and the chimney does not intersect the ridge, and its Table R1003.20 sets the cricket's height as a fraction of the chimney width by roof slope. The same rule appears among the roof-assembly flashing requirements in Section R903.2.2, which extends it to any roof penetration more than 30 inches wide.

What it costs and who does it

A cricket is a small framing-and-flashing job, priced as a line item: carpentry to frame and sheathe it, sheet metal or membrane to flash it, and roofing to cover it, plus the step flashing and counterflashing at the chimney it protects. Built during a re-roof it is cheap because the crew and the open deck are already there; built on its own it carries a service call and the cost of opening and re-closing the surrounding roof. A roofing contractor does the work; the counterflashing let into the brick is sometimes a mason's. The directory's roof repair cost guide describes how small jobs like this are priced.