The gap problem
Water does not always fall straight off a roof. In light rain especially, it clings to the underside of shingles and the roof deck and follows the edge back toward the house (surface tension). If nothing stops it, it runs down the face of the fascia behind the gutter, soaks the wood and drips out behind the gutter onto the wall or the ground by the foundation. Over years, that means rotten fascia and roof decking, stained siding and a wet foundation, even with clean gutters.
Drip edge and gutter apron are flashing pieces that bridge the gap between the roof edge and the gutter and break that path.
Drip edge
Drip edge is a bent metal strip installed along the edge of the roof deck, under the shingles. Its lower flange sticks out past the fascia so water drips off away from the wood. Common profiles are:
- Type C (L-shaped): a simple bent angle.
- Type D (T-shaped or “D-style”): an angle with an extra outward kick at the bottom that throws water farther from the fascia. It is common on eaves above gutters.
- Type F (extended flange): a longer lower leg, used when re-roofing over existing drip edge or to reach farther out.
What the building code says
Since the 2012 International Residential Code, drip edge has been required at the eaves and gables of asphalt shingle roofs (section R905.2.8.5). The code language, as adopted in many states, says drip edge must overlap by at least 2 inches between pieces, extend at least 1/4 inch below the roof sheathing and at least 2 inches up the deck, and be fastened at no more than 12 inches on center. Underlayment goes over the drip edge at the eaves and under it at the gables. Local amendments vary, so check your jurisdiction.
The FORTIFIED standard from IBHS goes further: its re-roofing checklists call for drip edge installed over the underlayment and fastened about 4 inches apart in a staggered pattern, because the roof edge is where wind damage begins. See FORTIFIED roofs and gutters.
Gutter apron
A gutter apron is a flashing strip that slides under the first course of shingles (and often under the drip edge or in place of it on the eaves) and extends down into the gutter itself. Where drip edge sends water off the edge, the apron guides it all the way into the gutter. It is especially useful when:
- there is a gap between the roof edge and the back of the gutter;
- the roof has no drip edge or the drip edge is too short;
- the gutter hangs slightly low, so water misses it.
Some installers use a combination: drip edge on the rakes (gables) and gutter apron on the eaves where gutters hang.
How it should meet the gutter
The lower edge of the drip edge or apron should end over the gutter, not behind it. With most gutters, the back of the gutter sits against the fascia and tucks under the drip edge or apron flange, so water lands inside the trough. If the gutter hangs too low (common when installers skip the drip edge or set the slope too steep), water can run behind it anyway. See how to measure for gutters for slope basics.
Signs you are missing drip edge or apron
- Water stains, drips or moss on the fascia behind the gutter
- Peeling paint on the fascia and soffit
- Wet or dark roof decking at the eaves when viewed from the attic
- Streaks on the siding below clean gutters
- Gutters that stay dry while water drips behind them in light rain
Can it be added without a new roof?
Often yes. A gutter apron can usually be slid under the first course of shingles by carefully lifting them, which is easier on newer, flexible shingles than on old, brittle ones. Drip edge is harder to add later because it belongs under the underlayment at the eave, so it is best installed during a re-roof. If shingles are old and brittle, lifting them may crack them, and it may make more sense to add the apron when the roof is replaced.
When gutters are replaced, it is a good time to check the edge. If the fascia behind the old gutter is rotten, the missing flashing is often the reason. See fascia repair before new gutters.
Drip edge on the rakes
The gable ends of a roof (the rakes) do not have gutters, but they still need drip edge. There, it protects the edge of the roof deck from wind-driven rain and keeps water off the rake boards. On the rakes the code places the drip edge over the underlayment, the opposite of the eaves. Where a rake meets a gutter at a corner, the two pieces of flashing have to be lapped so water flows into the gutter end rather than behind it; a small kick-out or diverter at that corner is common on complex roofs.
Kick-out flashing: the other edge detail
Where a roof edge meets a wall, such as a lower roof running into a second-story wall, a kick-out flashing at the bottom of the step flashing directs water into the gutter instead of down the wall. Missing kick-outs are a common cause of rotted siding and sheathing below roof-to-wall intersections. If you see stains or soft siding just below where a roof meets a wall, ask the installer to check for one.
Materials
Drip edge and apron are usually aluminum or galvanized steel with a painted finish, sometimes copper on historic or high-end homes. Match the metal to your gutters to avoid galvanic corrosion, especially near the coast. See gutters near the coast. Colors can be matched to the gutters or fascia; see how to choose gutter color.
Guards and the roof edge
Many gutter guards rest on or slide under the drip edge or first course of shingles. Guards that lift shingles or require fastening through the roof edge can void shingle warranties or weaken the edge in high winds. Ask how a guard attaches before buying. See are gutter guards worth it?