Safe Spans For No 1 Roof Rafters

Dead load weight of structure and fixed loads 15 lbs ft 2.

Safe spans for no 1 roof rafters.

Contact a building control officerfor advice. Span calculator for wood joists and rafters also available for the android os. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. This type is used to determine the length of the common valley hip and jack rafters and the angles at which they.

1 psf lb f ft 2 47 88 n m 2. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. Span calculator for wood joists and rafters available for the iphone. 1 ft 0 3048 m.

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. For example 2 by 6 rafters made from select structural grade douglas fir that are required to support a live load of 20 pounds per square inch can have a maximum horizontal span of 11 feet 4 inches. Decreasing the distance between rafters to 12 inches however increases the maximum span to 14 feet 4 inches. The other type of table gives the actual length of a rafter for a given pitch and span.

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. Maximum floor joist span no. The maximum spans in the table above are for the horizontal distance the rafter can span not the diagonal distance or actual length of the rafter.

Let s use this example and find a size of rafter that will work. Type 1 figure 7 10 appears on the face of the blade. 2 are indicated below. Rafter table type 1.

So if your house is 26 feet wide and the roof ridge beam is centered on the house you will need a rafter that can span 13 feet. The tables below give maximum spans for rafters and beams. 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. Given in the table.