Calculating Flat Roof Snow Loads on Structures per ASCE 7-10, Chapter 7

April 26, 2018 Abdul Siraj, P.E.

In this post, I will provide a brief overview of calculating flat roof snow loads that are specified in ASCE 7-10, Chapter 7. Before diving deeper, it’s a good idea to review the definitions of parameters used in the snow load formula. 


Parameter Definitions


Ce = Exposure Factor, ASCE 7-10 Table 7-2

Ct = Thermal Factor, ASCE 7-10 Table 7-3

Is = Importance Factor, ASCE 7-10 Table 1.5-2

pg = Ground Snow Load, ASCE 7-10 Figure 7-1 and Table 7-1



Flat Roof Snow Load Formula, ASCE 7-10, Equation 7.3-1


pf = 0.7CeCtIspg


Flat Roof Snow Load = 0.7 times the exposure factor times the thermal factor times the importance factor times the ground snow load