Dead load weight of structure and fixed loads 15 lbs ft2.
Roof rafter deflection limit.
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.
Maximum deflection limits are set by building codes.
Roof beam single span.
Floor joists ceiling joists rafters snow load rafters roof live load deflection limit.
Supporting roof and floor.
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.
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.
So these are the limits set by the code.
L 720 l 600 l 480 l 360 l 240 l 180.
This is the easiest way to determine allowable dead loads live loads and deflection limits.
If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6.
1 psf lbf ft2 47 88 n m2.
Default deflection criteria for the following members.
Clear span in inches l over a given number.
Ridge beam double span.
Live load is weight of furniture wind snow and more.
For sandwich panels used in roofs or walls of sunroom additions or patio covers the total load deflection shall not exceed l 120.
2 are indicated below.
3 stud construction standard utility.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
L 240 for unplastered floor construction.
For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360.
The deflection of floor and roof assemblies shall not be greater than l 360 for plastered construction.
The l is the length in inches of the clear span of the joists or rafters that make up the ceiling.
The code section on working load deflection states.
2x4 2x6 2x8 2x10 2x12.
Roof beam double span.
This publication has a much more extensive.
Spacing in 12 16 19 2 24.
Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection.
The maximum allowable deflection of a ceiling is expressed as a fraction in the format l x.
See the table below.
Ridge beam single span.
