Roof Rafter Deflection Limit

You can also use af pa s span tables for joists and rafters.

Roof rafter deflection limit.

For sandwich panels used in roofs or walls of sunroom additions or patio covers the total load deflection shall not exceed l 120. The code section on working load deflection states. Supporting roof and floor. 2x4 2x6 2x8 2x10 2x12.

If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6. They are expressed as a fraction. 3 stud construction standard utility. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Floor joists ceiling joists rafters snow load rafters roof live load deflection limit. Ridge beam double span. Dead load weight of structure and fixed loads 15 lbs ft2. Ridge beam single span.

See the table below. L 240 for unplastered floor construction. 2 are indicated below. The deflection of floor and roof assemblies shall not be greater than l 360 for plastered construction.

Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection. For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360. This publication has a much more extensive. A floor joist appropriately selected to span 10 feet with an l 360 limit will deflect no more than 120 360 1 3 inches under maximum design loads.

And l 180 for unplastered roof construction. For continuous aluminum structural members supporting edge of glass the total load deflection shall not exceed l 175 for each glass lite or l 60 for the entire length of the member whichever is more stringent. The l is the length in inches of the clear span of the joists or rafters that make up the ceiling. So these are the limits set by the code.

1 psf lbf ft2 47 88 n m2. Spacing in 12 16 19 2 24. Roof beam double span. Live load is weight of furniture wind snow and more.

The maximum allowable deflection of a ceiling is expressed as a fraction in the format l x. Maximum deflection limits are set by building codes. L 720 l 600 l 480 l 360 l 240 l 180. Roof beam single span.

On a roof with a slope greater than 4 to 12 the live load limit is typically adjusted downward from 20 psf to 15 psf to allow for the relatively greater dead load on the steeper roof.