Roof Rafter Deflection Limit

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.

Roof rafter deflection limit.

The deflection of floor and roof assemblies shall not be greater than l 360 for plastered construction. Clear span in inches l over a given number. Supporting roof and floor. Roof beam double span.

The l is the length in inches of the clear span of the joists or rafters that make up the ceiling. Default deflection criteria for the following members. For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360. Ridge beam double 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. Ridge beam single span. If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6. Floor joists ceiling joists rafters snow load rafters roof live load deflection limit.

You can also use af pa s span tables for joists and rafters. Roof beam single span. Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection. 2 are indicated below.

For sandwich panels used in roofs or walls of sunroom additions or patio covers the total load deflection shall not exceed l 120. This publication has a much more extensive. Spacing in 12 16 19 2 24. 3 stud construction standard utility.

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. L 720 l 600 l 480 l 360 l 240 l 180. 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. 1 psf lbf ft2 47 88 n m2.

The code section on working load deflection states. The maximum allowable deflection of a ceiling is expressed as a fraction in the format l x. This is the easiest way to determine allowable dead loads live loads and deflection limits. Maximum deflection limits are set by building codes.

And l 180 for unplastered roof construction. See the table below. Live load is weight of furniture wind snow and more. So these are the limits set by the code.

L 240 for unplastered floor construction.