Lumber Roof Spans

1 in 25 4 mm.

Lumber roof spans.

The total load is 4 000 pounds. Use these two tables for roof rafters with a slope greater than 3 in 12. 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. 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.

Live load 20 lbs ft 2 956 n m 2. 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 above spans are based on american softwood lumber standard sizes. Nominal actual surfaced size dry size 2 x 4 1 1 2 x 3 1 2 2 x 6 1 1 2 x 5 1 2 2 x 8 1 1 2 x 7 1 4 2 x 10 1 1 2 x 9 1 4 2 x 12 1 1 2 x 11 1 4 4. Live load is weight of furniture wind snow and more. 2 are indicated below.

For the initial calculation f can be estimated at 1 000. Using table f 2 figure 3 check each lumber size to see if a 16 inch spacing will permit a span of 15 feet 1 inch. 1 psf lb f ft 2 47 88 n m 2. Span calculator for wood joists and rafters also available for the android os.

Spaced sheathing or 1x boards may be reduced slightly. 1 ft 0 3048 m. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. For additional species of lumber check out the rafter span calculator from the american wood council website.

Dead load weight of structure and fixed loads 15 lbs ft 2. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders. View allowable load tables. Also available for the android os.

These sizes are as follows. F stands for the beam s fiber strength in bending which depends on the species of wood. In the example the beam spans the 10 foot width of the roof. The lengths and sizes of joists vary depending on the species and quality of the lumber used.

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.