Open data · state building codes
Ground snow loads by county
Ground snow loads for 170 counties, taken straight from the state building codes that list them — plus a calculator that turns pg into a flat or sloped roof snow load using the simplified ASCE 7 method.
States
Frequently asked questions
What is ground snow load (pg)?
The ground snow load is the weight of snow on the ground that the building code uses as the starting point for roof snow loads, in pounds per square foot (psf). The roof load is then adjusted for exposure, heat loss, importance and roof slope — and for drifts.
Where do these numbers come from?
Only from states whose building code itself lists a ground snow load per county or jurisdiction. Elsewhere, ASCE 7 site-specific values come from the ASCE Hazard Tool; check which edition your jurisdiction has adopted and confirm with the building department.
How do I convert psf to kN/m²?
1 psf = 0.0479 kN/m² (kPa). A 50 psf ground snow load is about 2.39 kN/m².
Values are transcribed automatically from the state administrative codes named on each page (public law). County names and centroids: US Census Bureau Gazetteer (public domain). Always confirm design loads with the local building official — some jurisdictions adopt amendments or require site-specific values.