Drip Edge Requirements — Where It Goes & How It Laps

Drip edge stopped being optional in the IRC years ago — asphalt shingle roofs must have it at both eaves and rakes. The trick most installers get wrong is the layering: underlayment goes over the drip edge at the eaves but under it at the rakes, so water always drains onto metal, never behind it.

Worth knowing

• An easy way to remember the layering: think about where the water is. At the eave it is on the underlayment heading down, so metal goes under. At the rake it is being blown sideways across the surface, so metal goes over.
• In ice barrier territory, the ice and water shield at the eave laps over the drip edge the same way underlayment does — set the metal first, then membrane onto it.
• Gutter apron and drip edge are different profiles. At an eave with gutters, a gutter-apron style that directs water into the gutter beats a standard D-profile hanging behind it.
• Re-roofs count: tearing off to the deck triggers current code, so a 1990s roof that never had drip edge gets it on the new roof.

Common questions