2 are indicated below.
Roof rafter deflection limit.
See the table below.
The code section on working load deflection states.
Roof beam single span.
L 720 l 600 l 480 l 360 l 240 l 180.
They are expressed as a fraction.
Note it gives the allowable deflection based on a fractional span quantity so a larger denominator will yield less deflection.
Roof beam double span.
This is the easiest way to determine allowable dead loads live loads and deflection limits.
3 stud construction standard utility.
Ridge beam double span.
Clear span in inches l over a given number.
Default deflection criteria for the following members.
The deflection of floor and roof assemblies shall not be greater than l 360 for plastered construction.
For example the allowable deflection of a 12ft span floor joist with plaster l 360 is 0 4 12ft divided by 360.
1 psf lbf ft2 47 88 n m2.
Spacing in 12 16 19 2 24.
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.
The maximum allowable deflection of a ceiling is expressed as a fraction in the format l x.
Live load is weight of furniture wind snow and more.
2x4 2x6 2x8 2x10 2x12.
Dead load weight of structure and fixed loads 15 lbs ft2.
For sandwich panels used in roofs or walls of sunroom additions or patio covers the total load deflection shall not exceed l 120.
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.
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.
You can also use af pa s span tables for joists and rafters.
Floor joists ceiling joists rafters snow load rafters roof live load deflection limit.
So these are the limits set by the code.
Maximum deflection limits are set by building codes.
And l 180 for unplastered roof construction.
Supporting roof and floor.
If that same joist had gypsum ceiling l 240 the allowable deflection is 0 6.
The l is the length in inches of the clear span of the joists or rafters that make up the ceiling.
