How to Install Gutter Apron: Bridging the Gap Between the Roof and the Eavestrough
Gutter apron carries water from the roof edge into the eavestrough, and keeps it off the fascia when the gutter sits below or back from the edge.
- Intermediate
- 2 to 4 hours for a typical house
- Updated
The short answer
Gutter apron is a flashing with a long roof flange and a drip leg that kicks out over the back of the eavestrough. Fasten it to the deck at the eaves under the underlayment, with the lower edge extending about 1/2 inch into the gutter. Where the gutter is hung tight to the fascia, add back flashing behind it so water cannot run between the gutter and the board.
Gutter apron looks like a long drip edge, and on many roofs it plays the same role. The difference is in the geometry. A gutter apron has a wider roof flange and a longer, angled leg that kicks out away from the fascia, so water coming off the roof edge lands inside the gutter and not behind it. It is used where the eavestrough is hung low, set back from the fascia or fixed on brackets that leave a gap.
When water runs behind a gutter, it soaks the fascia and the rafter tails, and that is where rot begins. Fascia boards that rot from behind are the most common edge repair in wet climates like the Fraser Valley. A gutter apron, and where needed a back flashing, closes that gap.
Most of the installation is like drip edge, so read how to install drip edge for the layer order. This guide covers what is specific to the apron and its relation to the eavestrough.
Tools
- Tin snips
- Hammer or coil nailer
- Hand seamer
- Chalk line
- Tape measure
- Sheet metal brake (optional)
- Level
- Cut-resistant gloves
Materials
- Gutter apron, aluminum or galvanized steel, in 10 foot lengths
- Corrosion-resistant roofing nails
- Ice and water shield and underlayment
- Drip edge for the rakes
- Sealant compatible with metal
- Back flashing strip where needed
Safety first
- Stay tied off at the eaves. Gutters may be in place, and a ladder against a gutter can bend it or slip.
- Cut metal edges are sharp. Wear cut-resistant gloves and eye protection.
- If the gutters are loaded with debris or ice, do not lean on them or use them for support.
- Do not work above people. Metal scraps and tools fall quickly.
Step by Step
Step 1: Check how the gutter hangs relative to the roof edge
Look at where the water will land. A gutter that hangs level with or slightly below the roof edge and close to the fascia takes water easily. A gutter set out from the fascia, or hung lower, leaves a gap that water can run into. Note the gutter's back lip height and whether it is tight to the fascia.
Also check the gutter slope and condition. A gutter that sags or overflows soaks the fascia whatever flashing is fitted. See the gutter notes on the fascia and soffit page.
Step 2: Choose the apron or drip edge that suits the gutter
Standard drip edge is often enough for a gutter tight to the fascia. A gutter apron, with a longer leg and a wider kick, is better where the gutter is farther from the fascia, where the roof has a small overhang, or where the fascia is covered with cladding that leaves a gap. Many roofers use apron on any eave where a gutter will hang.
Choose a leg length that reaches into the gutter by about 1/2 inch without touching the bottom. Colour-matched metal looks best, since it is visible from the ground.
Step 3: Fasten the apron to the deck at the eaves
As with drip edge, at the eaves the apron goes on the bare deck, and the underlayment and ice and water shield lap over it. Nail along the upper part of the flange about every 12 inches. Do not nail through the leg, which must remain free of holes where water runs. See how to install ice and water shield for the layer order.
Keep the apron in a straight line, using a chalk line. The kick should angle down and out, so a drip falls into the gutter and not back onto the fascia.
Step 4: Set the leg so water lands inside the gutter
Bend the apron leg with a hand seamer or a brake so its lower edge reaches just past the back edge of the gutter. If it stops short, water runs behind the gutter. If it extends too far, it can collect debris or block the gutter outlet. Check at the low and high ends of the gutter, because slope changes the gap.
Some roofers add a hem on the lower edge to stiffen the metal and to prevent water clinging and running back.
Step 5: Lap the joints and cut corners
Joints should overlap about 2 inches, nailed through both layers high on the flange. At outside corners fold the metal, and at inside corners cut a mitre and lap the pieces. Seal with compatible sealant where the manufacturer allows, but rely on the overlap. At the eave to rake corner, the rake drip edge laps over the apron.
Step 6: Add back flashing where the gutter is tight to the fascia
Back flashing is a thin strip that goes up under the apron or drip edge and down behind the gutter's back lip, so water that runs around the end of the apron or over the back edge of the gutter is caught and directed into the gutter. It is especially useful where gutters are installed after the roofing, or where hanger brackets hold the gutter away from the wall.
Some installers combine the strip with the gutter, known as a gutter with an integral back flashing. Ensure the top of the strip is under the apron, not over it, so water sheds correctly.
Step 7: Reinstall or check the eavestrough
The gutter should slope toward the downspout, commonly about 1/16 to 1/8 inch per foot, and the front lip should be slightly lower than the back so overflow goes out the front, not over the fascia. Check that the gutter hangers are fastened into the rafter tails or the fascia firmly. Then water flows from the roof, over the shingle edge, onto the apron and into the gutter.
Gutter Apron vs Drip Edge
- Drip edge: short flange and leg, hugs the fascia. Suits a gutter tight to the fascia.
- Gutter apron: long kicked leg that reaches into the gutter. Suits a gutter set out, low or on brackets.
- Back flashing: separate strip behind the gutter. Used with either when water can get behind the gutter.
- Both: follow the same layer order: under the underlayment at the eaves, over it at the rakes.
Fraser Valley Notes
Long wet winters mean gutters run for months and overflow when clogged with needles and leaves from fir and cedar. Overflowing water is what finds gaps behind the gutter. Clean the gutters and check the apron leg each fall, and replace any fascia that was already wet. See how to replace a rotten fascia board.
Common Mistakes
- Apron leg stops short of the gutter. Water falls behind the gutter and rots the fascia.
- Apron over the underlayment at the eaves. Water that gets through the roof runs behind the metal.
- Nailing through the leg. It leaves holes where water runs.
- No back flashing where the gutter is set away from the fascia. Water finds the gap.
- Gutter sloped the wrong way. Overflow runs down the fascia anyway.
- Leaving out the kick. Without a drip angle, water clings and runs back under the metal.
When to Call a Professional
If the gutters are in place and need to come off, if the fascia is rotten, or if the eaves are high, hire a roofer or gutter installer. Gutter apron and gutters should be coordinated, and each affects the other's performance.
A contractor can also check the roof edge, the fascia and the gutter alignment together when the roof is being replaced.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Fascia and Soffit service or the towns we cover.
How to Install Gutter Apron: Questions
What is gutter apron?
Gutter apron is a metal flashing installed at the roof eaves. One leg lies on the roof deck and the other angles out and down over the back of the eavestrough, so water running off the roof falls into the gutter and not behind it. It is like drip edge but with a longer, kicked-out leg for gutters that sit away from the fascia.
What is the difference between gutter apron and drip edge?
They do similar jobs. Drip edge has a short leg that covers the fascia top and suits a gutter tight to the board. Gutter apron has a longer, angled leg that reaches into the gutter, so it suits gutters set out from the fascia or hung lower. Both go under the underlayment at the eaves.
Does gutter apron go under shingles?
The roof flange goes on the bare deck at the eaves, then the ice and water shield and underlayment lap over it, and the shingles go on top of those. Shingles overhang the metal slightly so water drips off their edge onto the apron and into the gutter. The leg below the deck edge is visible.
Do I need back flashing behind my gutters?
It helps where the gutter is hung away from the fascia or sits low, because water can run behind the back lip. A strip of flashing tucked under the apron or drip edge and hanging behind the gutter catches that water. If the gutter sits tight to the fascia under a good apron, it may not be needed.
Why is water running behind my gutters?
Usually because the drip edge or apron is missing or too short, the shingles do not overhang the edge, or the gutter is set too far from the fascia. Overflowing gutters also push water behind the back lip. Fixing it means lengthening the drip leg with apron or back flashing and cleaning the gutters.
Related Guides
All Roof Edges, Fascia and Soffit guides|The full How-To Library
This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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