Flat Roof Rafter Spacing

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.

Flat roof rafter spacing.

If you get premium kiln dried lumber then you could span 10 5 with the same size of lumber and. For instance 2 grade 2x4s at 16 on center will span just over 9. Learn the 1 rafter design that will guarantee your roof that is safe and strong for years to come. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

For standard shed roof rafter spacing see rafter span chart. Rafter spacing is based on the width of the metal roofing panels. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. 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.

2 4 rafters can span up to 7. Boarding to be fastened on top of flat roof joists with a depth to width ratio greater than 4 the allowable clear spans have been calculated in accordance with bs 5268 2 2002 structural use of timber part 2. Live load is weight of furniture wind snow and more. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. For light load roofs 24 o c. Wider panels allow for greater spacing between rafters. Dead load weight of structure and fixed loads 15 lbs ft 2.

There is no standard spacing it depends on what size of rafters you want to use and the span of your shed. 1 psf lb f ft 2 47 88 n m 2. 2 are indicated below. Code of practice for permissible stress design materials and workmanship and bs 5268 7 2 1989 structural use of timber section 7 2.

Discover the pros and cons to multiple roof designs. This is our ultimate roof rafter guide for people designing and building an off grid cabin or tiny home. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof. 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.

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. Builders aren t bound by standard rafter spacing measurements. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.