Lumber Roof Spans

1 in 25 4 mm.

Lumber roof spans.

Allowable spans for 2x4 top chord trusses using sheathing other than plywood e g. For the initial calculation f can be estimated at 1 000. Tabulated spans apply to surfaced s4s lumber having dimensions which conform to the american softwood lumber standard ps 20 10. Also available for the android os.

Start with the 16 0 line in the spacing column at the left of the table then go to the right until you reach an appropriate span at least 15 feet 1 inch in this case. Live load is weight of furniture wind snow and more. These easy to use tables were compiled by the southern forest products association sfpa as a service to design build professionals and other southern pine users. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.

View size selection tables. Trusses must be designed for any special loading such as concentrated loads from hanging partitions or air conditioning units and snow loads caused by driftingnearparapetorslide offfromhigherroofs. So this table could accommodate a house with a total rafter span or house width of 32 feet. The lengths and sizes of joists vary depending on the species and quality of the lumber used.

The above spans are based on american softwood lumber standard sizes. Spaced sheathing or 1x boards may be reduced slightly. View allowable load tables. Use these two tables for roof rafters with a slope greater than 3 in 12.

1 psf lb f ft 2 47 88 n m 2. Live load 20 lbs ft 2 956 n m 2. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. The total load is 4 000 pounds.

Span calculator for wood joists and rafters also available for the android os. The spans in this table are based on a maximum supported rafter span of 16 feet where the supported span is the total horizontal distance spanned by the roof rafters divided in half not the diagonal distance or the length of the rafter. These sizes are as follows. Dead load weight of structure and fixed loads 15 lbs ft 2.

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. 1 ft 0 3048 m. F stands for the beam s fiber strength in bending which depends on the species of wood. For additional species of lumber check out the rafter span calculator from the american wood council website.

2 are indicated below.