Learn How to Frame a Sloping Shed Roof with Common Tools
Constructing a sloped shed roof adds character to a storage building while promoting proper drainage. With some basic carpentry skills and common equipment, DIYers can frame their own slanted roof without breaking the bank.
Before picking up a hammer, check local building codes for any requirements related to roof slope, materials, or permits. Planning ahead also includes thinking about your climate. Steeper pitches allow heavy rain or snow to run off easily but require taller walls. Moderate slopes around 4:12 are fine in drier areas.
Choose Your Slope
Typical sloped shed roofs have a pitch ranging from 4:12 to 8:12. This ratio refers to the roof's vertical rise over its horizontal span. A 4:12 pitch rises 4 inches vertically for every 12 inches horizontally.
Higher slopes are better for wet climates but may require extra framing. Flat roofs can work for simple lean-to structures but don't shed water well and are prone to leaking.
Calculate the Rafter Length
The slope determines the rafter length needed to achieve the desired roof height. This formula shows how to calculate the length:
- Desired height x (12 divided by pitch)
- For example, a 4-foot high roof with a 4:12 pitch would need 16-foot rafters:
- 4 feet x (12 divided by 4) = 16 feet
Mark the Angles
Cutting the correct angles on the end of each rafter ensures a tight and weathertight roof. Use a speed square or protractor to mark the "plumb" and "seat" cuts on the rafter ends based on the pitch you choose.
Assemble the Rafter Frame
With your rafters cut, it's time to assemble them into a sloped frame. Begin by securing one rafter into the corner of the shed wall top plates. Temporary braces will support the rafters until you install the roof sheathing.
Space the rafters equally, usually 16-24 inches on center. Measure from the outside of one rafter to the outside of the next. Use metal hurricane clips or wood gussets reinforce each connection.
Add Collar Ties
Collar ties placed horizontally between each rafter pair add stability and prevent the roof from sagging under snow load. Notch the ties into the rafters and nail into place.
Build the Overhangs
Overhangs provide shade and protect siding from water drips. Notch and install lookouts or outriggers to extend the eaves. Framing overhangs is easier if done before sheathing the roof.
Install the Roof Deck
With the framing complete, the next step is decking the roof. Start by laying roofing underlayment such as felt paper across the rafters. This adds a secondary water barrier beneath the shingles.
Space sheets of plywood or OSB across the rafters, leaving a 1/8" gap between sheets for expansion. Ensure panels span at least two rafter bays and meet on the center of a rafter.
Secure the Sheathing
Nail the roof deck into place with 8d galvanized nails every 6 inches along the edges and every 12 inches in the field of the panel. Follow a nailing pattern to ensure even fastening across the roof.
For extra wind resistance, also nail gable end panels and use adhesive between sheets. Don't forget to cover any exposed panel edges.
Once the structural framing and sheathing are complete, finish things off by installing fascia, trim, and soffits around the eaves. Flashing against walls and openings will help keep water out. The roof is now ready for shingles!
framing a sloping shed roof is a very doable weekend project. Just take it one step at a time, work safely, and follow code requirements. Soon you'll have stylish new storage space ready for your tools and toys.