Minimum Roof Rafter Size

Rafter tied to every joist.

Minimum roof rafter size.

Minimum number of nails not less than 75 mm long. Building width up to 9 8 m. Nominal vertical struts see figure 84. A roof that slopes less than 1 3 should be vertically supported at the peak.

This post may contain affiliate links. For more information see our disclosures here. 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. If you live in the us our snow load calculator compares the total weight on your roof with the permissible load calculated according to the standards issued by the american society of civil engineers regarding the minimum design loads for buildings and other structures asce7 16.

This can be accomplished by providing a 38 140 mm 2 6 in. 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. 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. The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that.

Supporting low slope roof rafters cmhc advice. 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 rafters spaced 20 or more inches apart 1 2 or 5 8 inch plywood is recommended.

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. Building width up to 8 0 m. Rafter tied to joist every 1 2 m. Patio roof maximum beam rafter spans.

Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. If your local building authority has a rafter spacing code you may not space rafters wider than required by code. 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.

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. Roof snow load kpa. This sizing guide for roof rafters will help determine what you need for your small project. Rafters must be strong enough to hold the roof sheathing and the shingles.

Roof snow load kpa. Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.