Minimum Roof Rafter Size

Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter.

Minimum roof rafter size.

There are several variables to consider when determining the proper rafter size. The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that. For rafters spaced 20 or more inches apart 1 2 or 5 8 inch plywood is recommended. This can be accomplished by providing a 38 140 mm 2 6 in.

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. Homepage metal roof metal roof purlins spacing and rafter distance details by rooflast posted on june 29 2020 june 29 2020 during the roof installation or re roofing process after the roof sheets are prepared it is time to support their framework by installing purlins. Building width up to 8 0 m. 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.

Rafter tied to joist every 1 2 m. Rafter tied to every joist. Roof snow load kpa. Roof snow load kpa.

While this clearly establishes the horizontal seat cut s minimum length its maximum length varies according to the size of the rafter and the pitch of the roof. For example the irc allows the ends of rafters to be notched as much as one fourth their depth r802 7 1 but on a shallow pitched roof this can result in a seat cut that s wider. Nominal ridge beam supported at 1 2 m 4 ft intervals by 38 89 mm 2 4 in. Building width up to 8 0 m.

This post may contain affiliate links. A roof that slopes less than 1 3 should be vertically supported at the peak. Rafters must be strong enough to hold the roof sheathing and the shingles. Roof snow load kpa.

For more information see our disclosures here. Roof snow load kpa. Nominal vertical struts see figure 84. Patio roof maximum beam rafter spans.

Building width up to 9 8 m. Supporting low slope roof rafters cmhc advice. An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.

Building width up to 9 8 m. Minimum number of nails not less than 75 mm long.