If the roof is not completely square you can decrease the space between joists but never increase the space.
Lean to roof joist spacing.
A roof joist is always spaced no more than 16 inches apart from another roof joist.
1 ft 0 3048 m.
Dead load weight of structure and fixed loads 15 lbs ft 2.
Enter this measurement into the calculator and select a roof pitch and the length of the rafter will automatically returned along with the rise.
2 are indicated below.
Spacing in exterior exposure.
Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.
A 4 by 10 can usually span up to 12 feet between posts.
In other words if there is a 1 1 2 ridge board nailed into the wall and the width of the lean to is 96 then the run will be 94 1 2 96 1 1 2 94 1 2.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
Span calculator for wood joists and rafters also available for the.
If you move up to 4 by 8 you re usually allowed to span up to 10 feet between posts.
Live load is weight of furniture wind snow and more.
1 psf lb f ft 2 47 88 n m 2.
Keep in mind that these figures depend on the size and spacing of joists and the overall structural loads.