R2 is a reduction factor for roof slope above 4 12.
Roof live load reduction formula.
No where it talks about any reduction is live load unless i am missing something.
They are not one and the same.
You can also find the load per square meter or square foot of roofing by opening the advanced mode.
The equation in the ibc is lr lor1r2.
Once you know these values our snow load calculator automatically finds the total weight of snow on your roof.
One for the tributary area supported by the structural element r 1 and the other for the slope of the roof surface r 2.
Snow load thickness density.
Also table r301 7 is for allowable deflection of structural members.
Snow load is different than roof live load.
For uses other than storage where approved additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such.
T 1x 300 300 sq ft 400 no live load reduction permitted.
However in my practice i typically use the horizontal run of the roof for both types of load.
The live load on a roof is the weight of any temporary objects on the roof.
If you want to calculate these values by hand use the following formulas.
Where snow isn t a problem the live load can come from people working on the roof and any equipment they.
R1 is for tributary area above 200 sq.
The building codes allow for a roof live load reduction for tributary area and roof slope.
I ignore the slope factor altogether for snow load reduction which adds another measure of conservatism.
If the roof design load is 20psf and you are considering the compression in a web member that is located near the mid span than i would not use live load reduction for the compression in that member.
The reduction formula has two reduction terms.
Roof live load reduction.
I am looking at irc2009 don t have irc2006.
L r l o r 1 r 2.
To do this i use conservative too heavy dead loads and full snow loads regardless of pitch.
Roof live load may be reduced by the following equation.
I live in a municipality that does not allow any roof live load reduction.
Live load reduction is a reduction in live load that contributes to the actions on a member.
The op s question was with regards to live load and you are referring to roof live load.
The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent but the live load shall not be less than l as calculated in section 1607 10 1.
Where l r shall not be less than 12 psf and not more than 20 psf.
