Flashing Takes Flight

Chimneys are one of the most common spots for roof leaks, and the reason comes down to a small but persistent problem. Wherever sheet-metal flashing wraps around a chimney's four corners, it has to be cut and bent in three directions, which leaves a tiny pinhole at each corner. Installers usually cover these with sealant or plastic corner pieces, but that sealant can fail over time, letting water into the roof below.

A design called winged flashing tackles this differently. Instead of relying on sealant to plug the pinholes, the metal is shaped with triangular "wings" that steer water around the corners entirely, away from the weak points. The wings also fold over and enclose any raw cut edges of metal, making the whole assembly stiffer and more resistant to water getting in, not just at the corners but overall. Getting the proportions right matters: bigger wings shed water better but can look bulky, while smaller ones blend in but do less to protect the upper corners, which take the brunt of water flowing down the roof.

For homeowners, the practical point is this: if you're having a roof redone or chimney flashing replaced, ask whether winged flashing is an option, since it's a more durable, leak-resistant approach than standard sealant-dependent flashing. It's also common practice, and sometimes required by code, to add a small peaked structure called a cricket on the uphill side of wider chimneys to route water around rather than let it pool against the chimney face.