Flat Roof Framing Spans

Some roofs actually slope in several directions ensuring optimal water runoff.

Flat roof framing spans.

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. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. 2 4 rafters can span up to 7. Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center.

Flat roofs are always built at a slight incline at least 1 8 inch per 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. Continuing on from part 3. Surveyors span tables for designing roof rafters.

1 psf lb f ft 2 47 88 n m 2. For heavy loads 2x4s can span up to 5. For pitched roofs flat roofs and ceiling joists. Dead load weight of structure and fixed loads 15 lbs ft 2.

Let s consider a basic gable wood roof framing design. Here we have a wood framed gable roof. You can do this with a foam layer that exactly fits your roof. Floor beam span tables of residential structural design we will now look at roof rafter and beam design.

Also available for the android os. The 1 grade material is more expensive than the 2 grade but if you can use fewer or smaller 1 grade joists or rafters in your design you may actually save money. 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. When framing a flat roof you will need to create a slight incline.

Rafter spans are tabulated for the most common roof loads. Live load is weight of furniture wind snow and more. For light load roofs 24 o c. 2 are indicated below.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. 1 ft 0 3048 m. This will help you create a flat roof framing plan. Span calculator for wood joists and rafters also available for the android os.

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. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. 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.