Where l r shall not be less than 12 psf and not more than 20 psf.
Roof dead load calculation example.
Roof live load reduction.
Used but they typically defined the load cases or combination stress or strength limits and deflection limits.
A table of roof material weights including sheathing insulation and other decking materials.
3 3 dead loads dead loads consist of the permanent construction material loads.
Technically you should use the actual rafter length when adding up the weight of roofing materials.
R 1 1 for a t less than or equal to 200 psf r 1 1 2 0 001 a t for between 200 psf and 600 psf.
However in my practice i typically use the horizontal run of the roof for both types of load.
Example roof truss analysis 3 6 stability determinacy assume that truss is externally statically determinate for gravity loads num forces 33 3 36 num eqns 18 x 2 36 therefore stable determinate dead load roof ceiling wt.
L r l o r 1 r 2.
Weight psf 20 ga metal deck 2 5 waterproof membrane with gravel 5 5.
To do this i use conservative too heavy dead loads and full snow loads regardless of pitch.
For wind the analysis of overturning should also consider roof uplift forces unless a separate load path is designed to transfer those forces.
Typical unit area dead load calculations.
910 pounds per lineal foot.
Load types loads used in design load equations are given letters by type.
Roof live load may be reduced by the following equation.
It is important to list live load dead load and total load separately because live load is used to compute stiffness and total load is used to calculate strength.
50 psf x 14ft 700 pounds per lineal foot.
6the 0 6 reduction factor on d is intended to apply to the calculation of net overturning stresses and forces.
15 psf x 14ft 210 pounds per lineal foot.
D dead load l live load l r live roof load w wind load s snow load e earthquake load r rainwater load or ice water load.
