Rafters must be strong enough to hold the roof sheathing and the shingles.
Rafter spacing for slate roof.
If your local building authority has a rafter spacing code you may not space rafters wider than required by code.
As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
Rafter and roof joist spacing is only one part of a complex roof design that works together to form a structure that meets building codes and can hold up the weight of the roof and roof load.
Wider panels allow for greater spacing between rafters.
For pitched roofs flat roofs and ceiling joists.
In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face.
A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel.
Rafter spacing is based on the width of the metal roofing panels.
Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings.
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.
Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.
Builders aren t bound by standard rafter spacing measurements.
Learn the 1 rafter design that will guarantee your roof that is safe and strong for years to come.
The boards creating the slope of the roof are wider than lumber used to build trusses 2x8s 2x10s and 2x12s are most common in rafters vs.
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.
This is our ultimate roof rafter guide for people designing and building an off grid cabin or tiny home.
Other imposed loads roof snow load and short term point load altitude not exceeding 100m.
Surveyors span tables for designing roof rafters.
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.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
Rafter boards are fastened to the ridge board at the peak and the top plate where they join the wall.
This is the distance between rafter centres.
