Shed Roof Rafter Design

Half building width minus 1 2 ridge thickness.

Shed roof rafter design.

For an 8 10 shed one sheet of plywood should be fine. Now you have extra 2 4 hanging over the bottom chord. However architects have recognized the potential of this form of design and now the shed roof is becoming a common feature among modern homes. It is possible to calculate a birdsmouth near the top of the rafter for a freestanding shed roof by checking the kneewall checkbox and entering a setback for the kneewall that positions the upper birdsmouth in the desired location.

This will allow them to join and form the peak of the roof and let the other end fit nicely at the 60 degree angle of the bottom chord. A shed roof slopes in one direction only. The exact length and angle of your rafters will depend on the overall size of your shed as well as the style and slope you ve chosen. A simple gable shed roof is often built using 2 4 or 2 6 lumber for the rafters and 2 4 for the collar ties.

The roof on this shed is a 4 in 12 slope which makes it a 18 and one half degree angle on the board ends. Measure your rafter boards for your preferred roof style and pitch. Print full scale rafter cut templates and birdsmouth templates fold template over rafter to mark or cut through. The rule of thumb is that the gusset should be twice the width of the wood you use for your rafters.

A gable roof for a shed can be built with rafters with a 1 6 ridge board or using trusses. The ridge end of the rafter and often the eve end will need to be cut to the angle of the roof slope. An alternative method of roof framing using purlins and roof trusses. A rafter or speed square will have marks for both of these angles.

Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. Easy rafters is designed to calculate shed roofs that are framed to a ledger board nailed against a vertical wall not freestanding shed roofs supported by walls at both ends. See rafter run to outer wall calculator below. So roughly 7 8 long for a 2 4.

By tying the rafters across at eaves level you stop the deadly eaves spread mentioned in method 1. So use your speed square and measure your angle. The rafters on a steeply sloped roof for instance will be much longer and have more end cuts than those on a flat roof. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.

You are going to cut out triangles that will cover the apex of each set of rafters. Then cut the rafter angle at 30 degrees for two 2 4 s. Trussed rafters this method of gable shed roof design makes each set of rafters into a lightweight truss.