Lumber Roof Size

Dimensional lumber and modern building.

Lumber roof size.

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. This means the example porch would need a 6 inch by 8 inch beam. All the figures are based on roofing tiles or slates laid on timber laths over sarking felt. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.

If there is are any questions about anything else then you should contact your supplier or an engineer. 1 psf lb f ft 2 47 88 n m 2. Most interior beams need to include the roof load. The dead load is constant and is estimated as 10 pounds per square foot for wood framed construction.

It has been my experience to never use a beam smaller than a two ply 2 x 8. For a porch roof the beam needs to be. Last updated july 15 2018. This tells you the size of the beam needed to support the porch s roof.

In the example d calculates to 7 75. Live load is weight of furniture wind snow and more. Pitched roof timber sizes. Dead load weight of structure and fixed loads 15 lbs ft 2.

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 calculator matches up with 90 of the applications in the 2012 international residential code book. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. Before lumber companies began selling osb the standard choice for sheathing a roof with a 24 inch rafter spacing was 1 2 inch cdx plywood the letters cdx indicate that it is construction grade.

The term dimensional lumber came into popular use around the beginning of the 20th century to distinguish lumber cut to pre determined sizes from other types of wood such as corded wood for fireplaces during this period the building industry sought to control costs and minimize waste by developing standard sizes and grades for building timber. This sizing guide for roof rafters will help determine what you need for your small project. 1 ft 0 3048 m.