Span Width Roofs Strength

While pitch and slope are used interchangeably they are not the same span also known as gable width this is based on the total footprint of the house and refers to the distance between two exterior walls.

Span width roofs strength.

For heavy loads 2x4s can span up to 5. Span calculator for wood joists and rafters also available for the android os. 2 4 rafters can span up to 7. Wood beam calculator american wood council website rafter and joist span faq.

Also available for the android os. Roof load width rlw and floor load width flw can be determined from as1684 or from the images below. The appropriate length of span varies according to the type of corrugation which refers to the folds or waves in the metal that give them their strength. F stands for the beam s fiber strength in bending which depends on the species of wood.

Spacing should be interpreted as the centre to centre distance between adjacent parallel members. Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. The lengths and sizes of joists vary depending on the species and quality of the lumber used. The total load is 4 000 pounds.

In the example the beam spans the 10 foot width of the roof. L stands for the span of the beam in feet. Panels with deep corrugation are usually stronger and can be used in longer spans than shallow corrugation. A 2x12 with an e of 800 000 psi and fb of 790 psi also works since it can span 15 feet and 10 inches.

While every effort has been made to insure the accuracy of the information presented and special effort has been made to assure that the information reflects the state of the art neither the west coast lumber inspection bureau the american wood council nor its members assume any responsibility for any particular design prepared from this online span calculator. 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. Fill in the parts of the formula that are already known. 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.

As the table shows no 2x8 s meet the span and spacing requirements but a 2x10 with an e of 1 300 000 psi and fb of 1093 psi can span 15 feet 3 inches more than enough. Required size for a given span. 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. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof.

For the initial calculation f can be estimated at 1 000. The width of panels depends on the type of corrugation.