Lumber Roof Spans

F stands for the beam s fiber strength in bending which depends on the species of wood.

Lumber roof spans.

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. Dead load weight of structure and fixed loads 15 lbs ft 2. Live load is weight of furniture wind snow and more. These sizes are as follows.

In the example the beam spans the 10 foot width of the roof. 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. The lengths and sizes of joists vary depending on the species and quality of the lumber used. Span calculator for wood joists and rafters also available for the android os.

Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders. 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. The total load is 4 000 pounds. 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.

Live load 20 lbs ft 2 956 n m 2. 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. Also available for the android os. View allowable load tables.

1 in 25 4 mm. Allowable spans for 2x4 top chord trusses using sheathing other than plywood e g. View size selection tables. Tabulated spans apply to surfaced s4s lumber having dimensions which conform to the american softwood lumber standard ps 20 10.

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. For the initial calculation f can be estimated at 1 000. For additional species of lumber check out the rafter span calculator from the american wood council website. The above spans are based on american softwood lumber standard sizes.

Use these two tables for roof rafters with a slope greater than 3 in 12. 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. 1 ft 0 3048 m. 2 are indicated below.

1 psf lb f ft 2 47 88 n m 2.