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