Drip Edge: Matching the Method to Your Roof Shape

You measured the roof. Now you face the install day question: does this edge go under the underlayment or over it, which profile belongs here, and how do the pieces meet at the corners? The answer changes with the shape of the roof. This guide maps gable, hip, shed, gambrel, and mansard roofs to the right method for each edge.

Which edges does your roof actually have?

Every install method in this guide attaches to an edge type: eave or rake. Eaves are the low horizontal edges where water leaves the roof. Rakes are the sloped edges running up a gable end. Count which edges your roof shape has before you buy a single stick.

This inventory also decides your piece counts: every run becomes sticks on its own, so knowing that a gambrel gable end has two rake runs instead of one changes the order. The roof measurement guide shows how to record each run, and the worked example shows the run-by-run conversion.

What goes on eaves and what goes on rakes?

The core method pair is the same on every shingle roof. At eaves, the drip edge goes on the bare deck first; the underlayment then laps over the top flange, so water traveling down the underlayment lands on the metal. At rakes, the order reverses: the drip edge goes over the underlayment, closing the side path where wind-driven rain pushes water sideways under the shingles.

Code fixes the same order. The IRC requires underlayment over the drip edge along eaves and under the drip edge along rake edges, with joints overlapped not less than 2 in (51 mm), the metal extending not less than 1/4 in (6.4 mm) below the sheathing and not less than 2 in (51 mm) back onto the deck.

Profile choice follows the edge. Type C is the simple L bend used along eaves. Type D is the T style with a wider projecting lip for rake edges. Type F, sometimes called gutter apron, has a longer face and is the usual choice where the eave feeds a gutter. Profile letters vary by supplier, so confirm the shape on the label. The lowest edge of the metal carries an outward bent flange, sometimes called a kickout, that throws water clear of the fascia.

How do corners and end joints meet?

Adjacent sticks overlap not less than 2 in (51 mm) so water cannot find a joint. At an eave-rake corner, the rake piece laps over the eave piece: water running down the rake lands on the eave flashing and continues into the gutter instead of diving behind it.

Outside corners are mitered, not butted. The usual trade method is a 45-degree notch cut in the roof flange so the face folds around the corner in one continuous piece. On a hip roof, where every edge is an eave, each outside corner gets the same folded treatment so the metal wraps the corner instead of meeting at a loose seam.

Which edges never get drip edge?

Drip edge belongs only on free roof edges. Putting it where a different flashing works invites double coverage and trapped water:

• Roof-to-wall joints (sidewalls and headwalls) get step flashing or a headwall apron, not drip edge.
• Valleys get valley metal, not drip edge.
• Hips and ridges get ridge caps, not drip edge.
• The top of a mansard and skylight or curb edges get coping, gravel stop, or the curb's own flashing.

The high edge of a shed roof is the clearest case: it is a headwall, and step or apron flashing that tucks into the wall is the correct method there.

How do ice dams and high wind change the method?

In ice-dam regions, the standard eave order can let water backing up from a gutter dam reach the deck edge. The asphalt roofing industry's trade guidance describes a sandwich variant: a starter strip of self-adhering underlayment goes on the deck first, the drip edge is installed over it, and the main underlayment course then laps over the metal. The drip edge ends up between two plies of underlayment, protected from meltwater backing up from below and from above. Check the shingle manufacturer's instructions before using this variant; some approve it and some do not.

In high-wind zones, federal building-science guidance tightens the whole method. Drip edge goes over the underlayment at both eaves and rakes, joint overlaps grow to at least 3 in (76 mm), fastening spacing drops to every 4 in (102 mm) or less, and the eave edges are sealed with flashing cement.

How is drip edge fastened?

Fasten with roofing nails through the top flange, set high enough that the next layer covers the nail heads. Trade guidance calls for nails 8 to 10 in (203 to 254 mm) on center, which satisfies the code ceiling of 12 in (305 mm). Never nail through the vertical face of the metal. Shingle courses then overhang the drip edge by 1/4 to 3/4 in (6 to 19 mm) at both eaves and rakes, so water leaves the shingle tip and falls free of the metal.

Which mistakes does this guide prevent?

• Installing the eave method on a rake and the rake method on an eave, then wondering where the leak started.
• Treating a hip roof's outside corners as laps instead of folding one continuous corner.
• Putting drip edge on a headwall or valley where step flashing or valley metal belongs.
• Running one method everywhere and missing the ice-dam sandwich or the high-wind fastening upgrade your climate calls for.
• Ordering sticks from a perimeter total when the roof shape changes how many runs each edge has.