For most do-it-yourselfers, framing the roof is the most challenging part of building a shed. But with a little understanding of roof styles, terminology and construction, roof framing is well within the capabilities of any weekend carpenter.
There are two basic ways to frame a shed roof. The traditional method is to cut and install all the parts—rafters, ridge board, collar ties, and ceiling joists—one board at a time. The advantage of this approach is that a single person can easily lift and nail the boards in place. However, you’ll spend a lot of time climbing up and down ladders, which can be exhausting.
The second option is to build the roof frame on the ground to form individual roof trusses. A roof truss is a prefabricated section of the roof frame that consists of a pair to angled rafters and one horizontal bottom chord, which forms the ceiling joist. Once assembled, the trusses are lifted up and fastened to the tops of the walls. Building and installing trusses is quicker and easier than piecemeal framing, but you’ll need help lifting the trusses into place. Now let’s take a detailed look at the three most popular styles of shed roofs: gable, saltbox, and gambrel.
A gable roof is by far the most common style of shed roof. It’s easily identified by its familiar A-shaped profile that has two sloping planes of equal length. Gable roofs are formed by pairs of common rafters that run at an angle from the tops of the walls up to the roof peak. A ridge board, if used, runs horizontally between the pairs of rafters where they meet at the peak.
Check your shed plans for the exact size and spacing of the lumber used to frame the roof. Most storage sheds are framed with 2×4 or 2×6 rafters, spaced 16 in. on center. The ridge board is often cut from a 1×6 or 1×8. When framing a roof with site-built trusses, you don’t need a ridge board. The rafters fit together tightly at the peak and are secured with plywood gusset plates.
Tip: Gable shed roofs look best with a roof slope of either 11-in-12 (40º) or 12-in-12 (45º).
A saltbox roof is similar to a gable roof except that one roof plane is slightly longer than the other. This unique design shifts the roof peak off-center so that it’s closer to the front wall, thus creating the distinctive saltbox roof. When framing a saltbox roof it’s important to follow two simple guidelines to maintain the roof’s proper proportions: First, run the rafters at 45º to create a 12-in-12 roof slope. Second, position the peak of the roof one-third of the way back from the front wall.
Tip: When framing the roof of a shed, be sure to set each rafter directly over a wall stud, which will transfer the roof load down to the foundation.
This design is often called a barn roof and is easily recognized by its distinctive double-sloping profile. It has two short, shallow roof planes that angle down from the peak, and then it breaks sharply to two steeper slopes that extend down to the tops of the walls. A gambrel roof is slightly more difficult to frame than other roof styles simply because it contains many more parts. The advantage though is that gambrel roofs create a very spacious interior with plenty of headroom above the ceiling joists, which can be utilized as a storage loft. Like most roof styles, a gambrel can be framed piecemeal one board at a time, or you can build trusses on the ground and then lift them into place.
Tip: When building a shed with a gambrel roof, it’s best to place the doors on the end wall because the sidewalls are typically too short to provide adequate headroom.
Shed Roof Sloping
A shed roof has a single sloping plane, making it the simplest of all roof frames to build. This style roof can be used on a freestanding outbuilding but is particularly well suited for sheds that are built up against another structure, such as a house, garage, stable or barn. In those situations, a horizontal ledger board is fastened to the existing wall to support the upper ends of the rafters. Shed roofs normally have with a relatively shallow slope, usually between 4-in-12 (18º) and 8-in-12 (33º).
Tip: When deciding on the slope of a shed roof, take into account the position of the doors. A steeply pitched roof comes down lower into the doorway than a slightly less-steep roof, and that could reduce headroom clearance.
Assembling the Shed Roof’s Substrate
The substrate is the surface where the roofing is applied. In many cases, a roof cover board is the best option for this, and there are several types. They are generally thin substrates which are installed between the insulation and membrane layers of the roof. They can help you avoid blistering in the roof system from the insulation off-gassing when coming into contact with certain adhesives being used for the roof.
The different types of roof substrates or cover boards are:
- Mineral fiber
- Wood fiber
- Gypsum fiber
- High-density polyiso
The substrate is installed by being fastened to the structural deck or to an underlying substrate. Many of the best installation techniques include staggering the joists of the cover board in each row and to the joints of the insulation below it. This reduces bridging and gaps between the layers.
Shed’s Roofing Materials
There are different types of roofing materials you can choose as you prepare to put the finishing touches on your roof.
- Three-tab shingles – This is the standard and it is also the most inexpensive option for a shed roof. The shingles are easy to install, which makes them a great do-it-yourself option. Many will include a warranty that lasts as long as 30 years.
- Metal – Metal roofs have a lot of advantages. They are lightweight and they often last longer than other types of roofing materials. They are weather-resistant, which is a great benefit. The only real drawback to metal is that it can be costly, but a lot of these roofing systems have 50+ year warranties.
- Cedar shakes – When cedar is properly maintained, it can last for as long as 35 years. This material is naturally insect resistant, and it also resists damage from the sun. It has a traditional appearance, and it could be a great option for those looking to pay mid-range prices for their roofing materials.
- Architectural shingles – Architectural shingles are actually two or more layers of asphalt that have been laminated together. They are much heavier than three-tab shingles, but they carry lifetime warranties. This type of shingle can bring an artistic element to the shed’s roof. They are usually used on residential buildings, which make them a popular option for sheds too.
How is Your Shed Roof Design Coming Along?
With the right materials, knowledge, and guidance, anyone can frame a shed roof. We hope that this guide has been helpful to you as you build your shed. We would love to hear about how your shed roof is progressing! Let us know in the comments!
Joseph Truini is a host on the Today’s Homeowner TV show and co-hosts the weekly Today’s Homeowner Radio Show. He has written three best-selling shed-building books and lives in Roxbury, Connecticut.