Roof Framing Rafter Spacing

Floor joists ceiling joists rafters snow load rafters roof live load deflection limit.

Roof framing rafter spacing.

Depending on the roof design and the roof rafter spacing. 3 stud construction standard utility. Rafters shall be framed to ridge board or to each other with a gusset plate as a tie. 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.

The same concept holds true for roof trusses. The provisions of this section shall control the design of truss roof framing where snow controls for buildings that are not greater than 60 feet 18 288 mm in length perpendicular to the joist rafter or truss span not greater than 36 feet 10 973 mm in width parallel to the joist rafter or truss span not more than three stories above. Subtract that number from the width of the panel and then divide by 2 to come up with the spacing for the rafters. Double the hill and valley width since this is the amount that the panel will overlap the one next to it on each side.

If you look at the rafter span chart you ll notice that 2x4s can be used for rafters on spans up to 11. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. The pitch and span of your roof will dictate how long of a rafter you ll need use maximum span calculator to help you find your rafter size. At all valleys and hips there shall be a valley or hip rafter not less than 2 inch 51 mm nominal thickness and not less in depth than the cut end of the rafter.

Spacing in 12 16 19 2 24. So if the pitch of your roof is 7 12 place one stair gauge on the vertical part of the framing square the tongue at the 7 inches 18 cm mark and place one stair gauge on the horizontal part of the framing square the body at the 12 inches 30 cm mark. 2x4 2x6 2x8 2x10 2x12. Ridge board shall be at least 1 inch 25 mm nominal thickness and not less in depth than the cut end of the rafter.

As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. So the space between rafters can be greater without reducing the maximum span. Rafter tie or collar tie spacing intervals connection specifications building codes such as the icc s 2012 international building code section 2308 10 roof and ceiling framing typically specify that where rafter ties are used they are required at intervals ranging from 12 to 24 o c. Anything beyond that you are looking at using 2x6s for most sheds.

L 720 l 600 l 480 l 360 l 240 l 180. This will give the framing square the angle you need to make the ridge cut.