Flat Roof Framing Spans

2 4 rafters can span up to 7.

Flat roof framing spans.

Floor beam span tables of residential structural design we will now look at roof rafter and beam design. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof. 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. Continuing on from part 3.

Some roofs actually slope in several directions ensuring optimal water runoff. For pitched roofs flat roofs and ceiling joists. Let s consider a basic gable wood roof framing design. For roof live loads less than 20 pounds per square foot psf rafter spans and required e values tabulated for 20 psf shall be permitted to be adjusted in accordance with the fol lowing table.

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. Live load is weight of furniture wind snow and more. 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. For heavy loads 2x4s can span up to 5.

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 can do this with a foam layer that exactly fits your roof. Flat roofs are always built at a slight incline at least 1 8 inch per foot. 2 are indicated below.

1 ft 0 3048 m. 1 psf lb f ft 2 47 88 n m 2. Span calculator for wood joists and rafters also available for the android os. Dead load weight of structure and fixed loads 15 lbs ft 2.

This will help you create a flat roof framing plan. Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. Here we have a wood framed gable roof. Rafter spans are tabulated for the most common roof loads.

When framing a flat roof you will need to create a slight incline. The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. Surveyors span tables for designing roof rafters. The loads are based on adjusted roof snow loads from the governing building code.

For light load roofs 24 o c. For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine. Also available for the android os.