Drip edges are critical for directing rainwater away from the fascia board and into the gutter. Nearly every roof has one, though it’s a choice rather than a code requirement.
Today we want to discuss drip edge sizes. Does the size matter? If so, what’s the standard drip edge size, and how do you determine the best size for your roof? We answer these and many other drip edge sizing questions below.
Drip edge flashing sizes
Roof drip edges are typically 10.5 feet long, though 8-foot or shorter edge flashing pieces are easy to come by. The overhang depth is typically 2-5 inches, while the flange over the decking is often 2.5 inches. However, these are industry averages. You can easily come across smaller and larger units.
What is a Drip Edge?
The drip edge is the metal flashing installed over the roof’s edge. You may not notice it if the gutter is already installed. Nevertheless, it takes advantage of surface tension and gravity to direct roof water away from the fascia into the gutter.
What Does a Drip Edge Flashing Do?
The drip edge flashing protects the roof and your home. The following are a few reasons you need one;
- Prevent damage to fascia and soffit: Storm water often splashes against an unprotected fascia board, increasing the risk of wet rot and insect infestation. It also weakens the fascia. Drip edges shield the fascia board from water damage.
- Stabilize the roof during winds and storms: The drip edge’s design deflects winds and storms above and below the roof, protecting the home from full-speed impact. Thus, it minimizes the risk of roof lift-off.
- Protects the basement and foundation: During storms, lots of water miss the gutter, instead splashing to the pavement and walkways below. The splashdown and water pooling can cause basement and foundation damage. Fortunately, the edge flashing eliminates this problem.
- Keep out small pests: Tiny pests, including ants and insects, love to creep into the gap between the shingles and decking or underlayment, where they establish colonies and damage various roofing components. An edge flashing keeps out most small pests.
- Protects roof deck edges: We’ve seen that storm rain can dampen and even damage fascia boards. Damp facia boards can easily transfer the water to the decking, causing rot. Thus, the drip edge protects the decking too.
Where is the Drip Edge Installed?
Drip edges are installed on the eaves and rakes of the roof, though the edge flashing installed on the rakes is commonly called rake edges.
Is the drip edge installed under felt? The drip edge is installed under the felt but above the decking material on the eaves. Meanwhile, the rake edge is installed above the felt. However, the requirements vary from one location to the next. So, it’s best to check your local building codes.
Does the drip edge go under or over metal roofing? The drip edge on the eaves goes under the underlayment, thus below the metal roof.
Does the drip edge go around the entire roof? Yes. The drip edge is installed along the entire roof perimeter to create a watertight seal along the roof’s edges.
Types of Drip Edges
Drip edge sizes depend on the edge flashing style. Therefore, it helps to understand the common edge flashing designs. The three main drip edge profile types are D-type, C-type, and F-type.
- Type D Drip Edge: Type-D drip edges are the best overall. They are shaped like the letter “T” with a flange at the bottom. The Asphalt Roofing Manufacturers Association (ARMA) recommends D-type drip edges as they keep water further from the fascia.
- Type C Drip Edge: Type C drip edges are classic L-shaped components bent at 90 degrees. Many feature a lower flange at the bottom to deflect water from the soffit. It’s an older style but still common in new roofs.
- Type F Drip Edge: Type-F drip edges are best for existing roofs. They feature longer leading edges that cover existing roof edges better. Many people call them gutter aprons.
You may also come across a rake edge and gable drip edge. These special-purpose edge flashing components are designed purposely for rakes and gable roof edges.
Drip Edge Types by Materials
Besides style, drip edges vary by material. The most common materials are aluminum, galvanized steel, copper, and non-metallic.
Aluminum drip edges are among the cheapest. They’re the cheapest among metal drip edges. Meanwhile, galvanized steel drip edges stand out for their durability. Galvanized steel edge flashing of the right thickness can last many years and potentially outlive the fascia board.
Finally, copper drip edges are premium elements adored for their beauty and charm. So, they’re a great choice if you wish to elevate your curb appeal.
What about non-metallic drip edges? International codes strictly demand metallic roof edge flashing, and we couldn’t agree more. Although some plastics, vinyl, and fiberglass grades are strong and durable, they are best for windows and doors.
Drip Edge Sizing
We strongly recommend working with a professional roofer or structural engineer to determine the best drip edge size for your roof. However, following industry standards and international code is another option.
In that case, the following are general guidelines from the International Residential Building Code (IBC).
Drip Edge Length
Most manufacturers sell drip edge flashing in 10-foot (120-inch) lengths. However, 8-foot-long drip-edge flashing is also common. The good news is that you can cut drip edges two resize them as appropriate.
If so, mark the cut line with a permanent marker. Then use tin snips and make a straight cut from the bottom of the drip edge.
Drip Edge Flange Size
The flange is the flat upper part of the drip edge that goes between the roofing panel/shingle and the underlayment. It’s also known as width and primarily prevents water from creeping up to the decking or underlayment.
Again, the flange size varies from one manufacturer to the next. However, the standard size is 2.5 inches wide. Wider sizes are available up to 5.75 inches (Union Corrugating) and 6.0 inches (Amrimax). But the choice comes down to what your local building codes say.
For instance, Texas adopts IRC guidelines which state that the drip edge shall extend “not less than 2 inches (51 mm) onto the roof deck.
Additionally, note that the flange provides the platform or surface for nailing the drip edge flashing onto the roof. So, you need enough space as nailing too close to the roof edge creates new leak issues.
Can you resize the drip edge flange? Unfortunately, no. Moreover, why shorten the drip edge when wider edge flashing provides better water protection? Instead, you should be worried if the flashing width is too short.
Drip Edge Vertical Height
The vertical edge is the section “hanging” below the roof, between the gutter and fascia board. We call it the height because it’s vertical to the house.
The correct height is critical to prevent water from reaching the fascia board or eaves in adverse weather. But more importantly, it prevents water from flowing back onto the decking. Thus, the drip edge must extend below the decking by at least 1/4 inch (6.4 mm).
For this reason, the standard size drip edge height is 1.5 inches, though 1 5/8 drip edges are also common. Deeper edges are available up to 3.5 inches. But, again, stick to the local building codes.
Drip Edge Lip Extension Size
The lip extension is only found in a Type-D drip edge. It is an extension of the flange but found on the opposite side of the vertical edge.
The drip edge lip extends over the gutter and is solely responsible for directing rainwater into the gutter system. Thus its size is partly determined by the gutter width.
For instance, a longer lip may block the gutter. Or worse, roof water may flow past the gutter onto the ground below.
That said, the standard drip edge lip extension is 0.5 inches. Speak with your roofer or a structural engineer to learn about other options.
Other Drip Edge Sizing Code Requirements
Beyond the length, width, and height, the following additional drip edge measurements apply;
Minimum Drip Edge Thickness (0.019 Inches)
The thickness of the drip edge material is just as important as the length, width, and height – and the IRC recognizes this.
IRC guidelines state that “where the flashing is of metal, it must be corrosion-resistant with a thickness not less than 0.019 inches. This is equivalent to 0.05 mm, or 26 gauge galvanized steel thickness.
The code must clearly spell out the required thickness, as most building supply stores only provide 0.011-inch edge flashing. This represents a 42% difference compared to the required 0.01-inch thickness.
Minimum Drip Edge Distance From Fascia Board (1/4 inch)
A properly installed drip edge leaves a tiny gap between the edge flashing and the fascia board. This gap is also known as the drainage gap and is an extra step to keep rainwater from the wooden fascia board.
The ideal drainage gap is 1/4 inch. A bigger gap can interfere with drainage as it pushes the drip edge far into the gutter. On the other hand, a smaller gap increases the risk of fascia water damage.
What Does the Fortified Home Guide say?
The Fortified Home Guide is a special guideline developed by the Institute for Business and Home Safety (IBHS) for areas prone to hurricanes and high winds.
First, it recommends a wider, 3-inch overlap between the first and next drip edge piece. This makes sense to prevent water creep and ensure a stronger structure.
Additionally, it recommends nailing the drip edge 4.0 inches on-center instead of 12 inches on-center. IBHS also suggests driving the roofing nails in a two-row W-pattern for extra attachment strength.
Finally, a sub-fascia between the drip edge and the main fascia board is advised to provide a solid nailing surface.
How to Install Drip Edges
Roof drip edge installation is best left to professionals. However, skilled DIYers can easily handle the task too. Here’s an overview of the installation process;
- Install a furring edge to keep the longer edge of the drip edge further from the home’s siding.
- Starting at the eaves, lay down the drip edge, aligning it, so water flows into the gutters
- Secure the drip edge using roofing nails. Nail high up on the drip edge, so the shingles cover the nails.
- Cut/trim the drip edge one inch from the overhang at the corner where the eave meets the rake. Then bend it at the overhang to form a corner.
- Install the roof underlayment. This way, the underlayment goes over the drip edge on the eaves but under it on the rakes.
- Install drip edges on the rake. When you get to the corners, bend the drip edge over the top of the existing flashing and cut/trim it to form a two-inch overlap.
Drip Edge Sizes FAQs
How far do you overlap drip edges?
Drip edges should overlap by an inch at least. Nail them every 12 inches or up to 16 inches at most. Then overlap the next drip edge by an inch. Be careful not to leave gaps between successive drip edges, as the spaces permit water backflow behind the gutter and onto the fascia.
If following the IRC guidelines, the document states that “adjacent edges of the drip edge shall not overlap by less than 2 inches (51 mm).”
What size drip edge for a shed?
There are no special drip edge sizes for sheds. For instance, standard drip edges are 10 feet or 8 feet long, which also applies to sheds. Meanwhile, the flashing is typically 2.5 inches to 6.0 inches. Consider wider flashing for maximum rain protection.
Summary
A standard roof drip edge is 10.5 feet long, extends 2.5 inches onto the roof decking, and overhangs the decking by 1/4 inch vertically. However, other dimensions are available depending on your building codes. Alternatively, stick by International Residential Building Code (IRC) guidelines.