Architecture

Snow Load Calculator

Convert ground snow load to design roof snow load using ASCE 7 factors. Plug in pg from your local map + roof type + slope.

Typical ground snow (pg) by region

Gulf Coast / Florida: 0-5 psf
Southern Plains, Mid-Atlantic: 15-25 psf
Ohio Valley, Midwest: 20-30 psf
New England, Upper Midwest: 40-60 psf
Mountain West / Northern New England: 70-100+ psf
High elevations (Cascades, Sierra, Rockies): 100-300+ psf

Get the exact pg for your site from ASCE 7 maps or your local building code amendments.

FAQ

What's the slope factor Cs? +

A reduction for steep roofs — snow slides off. Warm roofs (Ct = 1.0) start reducing at 30° (~7:12), zero at 70°. Cold roofs reduce less.

Drift loads? +

This calc gives the uniform load only. Drift loads at parapets, lower roofs, and equipment can be 2-3× the flat-roof value over a limited area. Critical for steel framing.

Snow density? +

Roughly 5-15 psf per foot of accumulation depending on age and moisture. 30 psf = ~2-3 ft of typical snow.