Lumber Roof Spans

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.

Lumber roof spans.

Use these two tables for roof rafters with a slope greater than 3 in 12. Dead load weight of structure and fixed loads 15 lbs ft 2. 1 in 25 4 mm. In the example the beam spans the 10 foot width of the roof.

View allowable load tables. For additional species of lumber check out the rafter span calculator from the american wood council website. 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. Spaced sheathing or 1x boards may be reduced slightly.

The lengths and sizes of joists vary depending on the species and quality of the lumber used. F stands for the beam s fiber strength in bending which depends on the species of wood. Live load 20 lbs ft 2 956 n m 2. Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.

1 ft 0 3048 m. The above spans are based on american softwood lumber standard sizes. Span calculator for wood joists and rafters also available for the android os. The total load is 4 000 pounds.

Also available for the android os. 2 are indicated below. Tabulated spans apply to surfaced s4s lumber having dimensions which conform to the american softwood lumber standard ps 20 10. Live load is weight of furniture wind snow and more.

Allowable spans for 2x4 top chord trusses using sheathing other than plywood e g. 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. 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. 1 psf lb f ft 2 47 88 n m 2.

So this table could accommodate a house with a total rafter span or house width of 32 feet. 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. View size selection tables. These sizes are as follows.

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.