Having a roof overhang on your shed can provide protection for windows and doors as well as allow for proper air ventilation for the roof if you have an attic space in the roof.
How much roof overhang is needed varies, most buildings have a 24 inch overhang. If the shed is small an overhang of 6 to 12 inches will be adequate, using a 24-inch overhang on a small structure will look out of place.
What are the Advantages of a Roof Overhang?
The main advantage is having the water run off from the roof fall away from the sheds walls and foundation especially if you’re not planning on using any type of guttering system to direct water away from the structure. In those regions where there is a lot of rain, you’ll shed the use of overhangs.
Another advantage is it allows for the installation of a vented soffit which lets air enter the roof cavity and exit thru the ridge venting preventing moisture from building up inside of the attic causing mold and rot.
The overhang vented soffit also prevents birds and other small animals from getting into the attic space and building nests. A screened vent is also used to prevent small insects like bees, wasps and other flying bugs from getting into the attic area.
The roof overhang is also part of a good design and makes the shed look more like the house. It also keeps rain from getting into doors, windows and helps keep wood siding from needing extra staining or painting. I use the overhang on my shed to protect some of my tools from the rain and it’s also a good place to stack some firewood for the winter. Check out my article The 7 Most Popular & Practical Shed Roof Designs for more information on different types of roofs.
How Far Can a 2×4 Rafter Overhang?
The maximum recommended overhang using 2×4 rafters at 24-inch centers is 24 inches that’s using a 1×6 facia board. If you use a 2×4 facia you can get another 4 to 6 inches, overhanging any more than that with a 2×4 rafter can cause problems especially if you live in a region that is subject to heavy wet snow.
You can increase the overhang to 30 inches if you put your rafters on 16-inch centers and use the 2×4 facia board. You also inch the strength of your roof overhang by using 5/8 inch or ¾ in plywood sheeting.
How Far Can a 2×6 Rafter Overhang?
Using 2×6 rafters you can increase your overhang to 36-inches to a maximum of 42-inches, if you need to have a roof overhang to go out to 4 to 5 feet, you’ll want to use engineered trusses that have the extra canter level supports built into them. That would be another 2×6 on top of the bottom chord going back twice the distance as the overhang. The problem with this is you may have to increase the pitch of the roof to allow for the extra framing for the added support piece.
How Far Can You Overhang Metal Roofing?
If you’re strapping your roof and using metal roofing you can extend the metal roofing 2 to 4 inches past the facia board. However, this will leave the unsupported metal subject to damage from ladders and ice damps. Depending on the thickness and rib design of the metal roofing your using will determine if you can extend the metal the maximum 4 inches pass the framing.
How Far Can You Overhang Shingles?
Fiberglass or asphalt shingles can overhang ¾ to 1 inch past the sheeting and eaves protection material. You can also extend the roof sheeting 3 to 6 inches depending on the thickness of the sheeting. This is not a recommended method to increase roof overhang as the plywood and shingles will sag over time.
How Much Gable Overhang Can I Use?
Gable overhangs add some nice appeal as well as providing protecting to the outside edge of soffits. The most common gable overhangs are between 12 inches and 24 inches with the odd roofs extending 30 inches. Depending on the sheds location and the wind that goes thru your region can affect the amount of overhang.
Extra anchoring and secure framing is required for the gable overhang especially in regions that hang lots of high winds. It’s always a good idea to talk to your local building authority before building the roof and overhangs.
How Are Gable Overhangs Made?
There are 2 types and depending on the type of roof framing your using will determine which method you can use.
Hand framing roof… This method uses a ridge board at the peak of the roof and rafters are attached there. If you’re wanting a gable overhang you will cut the ridge board longer to extend past the outside of the gable end the amount of the overhang you want, you would also extend the bottom facia past the same amount and then install the rafter in place.
If your shed is 10 feet or less in width then you won’t need any laddering supports, you can add a support block the same thickness as the rafter in the center of the rafter length for added support. The sheeting also reinforces the overhang giving the strength needed, if you live in a heavy snow load area you can add extra supports as needed.
Trusses… The main method to extend an overhang on the gable ends of a truss roof is to use a “drop gable” truss, the gable truss is made 1 ½ inches lower so you can nail 2×4 blocking from the full-size truss onto the drop gable truss which allows you to extend the blocking out to create the overhang.
The other option is to build a “ladder” which will require you to note out for 2x4s on the flat to create the overhang. For overhangs up to 12 inches going back to the first truss is required, if you’re going to be extending the overhang 24 inches then you’ll need to notch out 2 trusses to provide the strength for the wider overhang. Read my article Are Trusses a Better Choice for a Shed Roof? to find out if trusses are better then hand cutting your roof.
Having some roof overhang does provide protection and makes the shed look much more appealing and match most homes. It will add some extra cost for framing material and roofing material, if your on a budget you certainty can omit the overhang and use the savings somewhere else. If you want to save more money on your roof read my article What is the Cheapest Type of Roof to Build?