Chimney Flashing and a New Roof in Springfield, MA

How chimney flashing works

• Step flashing: L-shaped pieces woven into each course of shingles along the sides of the chimney
• Counter flashing: metal set into the mortar joints of the chimney that laps down over the step flashing
• Front apron: one piece across the downhill face of the chimney
• Back pan or cricket: protection on the uphill side, where water and snow pile up

The two layers work as a pair. The step flashing moves with the roof, the counter flashing moves with the chimney, and the overlap keeps water out as the house settles and the seasons change.

Why reuse is a bad bet

Old step flashing is nailed in with the old shingles and is often bent or cut during tear-off. On many older houses in Springfield, Holyoke and Chicopee the original flashing has also been covered with tar or caulk over the years, which hides rust and holes. Reusing it puts a new roof next to a weak point.

What a cricket does

A cricket is a small peaked structure behind the chimney that splits water and snow around it. The building code calls for one behind wider chimneys. On a western Massachusetts roof it also keeps snow from piling against the brick, where it melts and refreezes.

Questions for your roofer

• Will step and counter flashing be new, and what metal will it be?
• Will the counter flashing be cut into the mortar joints, or surface-mounted?
• Does the chimney need a cricket?
• Is the ice barrier carried up around the chimney?