❄️ Snow Load Calculator
Estimate the design snow load your roof needs to support, using the ASCE 7 flat-roof snow load formula and your local ground snow load.
What this calculator does
The snow load calculator estimates the design snow load a roof must be built to support, using the flat-roof snow load formula from ASCE 7, the U.S. structural design standard referenced by most building codes.
The formula
The flat-roof snow load is Pf = 0.7 x Ce x Ct x Is x Pg, where Pg is the ground snow load for your area (from local building code snow load maps), Ce is an exposure factor accounting for wind exposure and terrain, Ct is a thermal factor accounting for how much heat escapes through the roof, and Is is an importance factor based on the building’s risk category (higher for hospitals, schools, and emergency facilities).
This is a simplified planning estimate. Actual sloped-roof snow loads, drift loads, and minimum load requirements involve additional ASCE 7 provisions — always have a structural engineer confirm design loads using your jurisdiction’s official ground snow load and code requirements.