Drip Edge

A drip edge is a length of bent sheet metal, usually aluminium, galvanised or coated steel, or copper, installed along the roof edges. One flange lies on the roof deck; the other turns down over the edge, often with a small outward kick, so water dripping off the roof falls clear of the fascia and into the gutter rather than wicking back onto the deck edge and fascia board. It also stiffens and protects the edges of shingles and closes the gap between deck and fascia against wind-driven rain and pests.

US code requirements

The International Residential Code (section R905.2.8.5 in recent editions) requires drip edge at eaves and rake edges of asphalt shingle roofs; trade press dates the requirement to the 2012 edition. As adopted in Connecticut's 2022 code, for example, requirements include:

• adjacent pieces overlapped at least 2 in (51 mm);
• the metal extending at least 1/4 in (6 mm) below the roof sheathing;
• extending back onto the roof deck at least 2 in (51 mm);
• mechanically fastened to the deck at no more than 12 in (305 mm) on centre.

Some shingle manufacturers recommend closer fastening. States and cities can amend the model code: Virginia's building code, for instance, does not prescriptively require drip edge, but it must be installed where the shingle manufacturer calls for it.

Eaves versus rakes

The lapping order differs between edges:

• At the eaves, the underlayment goes over the drip edge so that water on the underlayment drains onto the metal.
• At the rakes, the drip edge goes over the underlayment.

Where an ice barrier is used at the eaves, manufacturer instructions specify whether the membrane goes under or over the drip edge.

Profiles and regional terms

Common profiles include the L-shaped, the T-shaped "D-style", and the gutter apron, which extends down into the gutter. In the UK, eaves trays, eaves carrier strips and verge trims perform related functions, and on tiled roofs the underlay is often carried into the gutter over a fascia board or eaves support tray.