FullCalculator

Roof Snow Load Stress Calculator

Formula

Snow Load (psf) = Snow Depth (ft) x Snow Density (lb/ft³) | Adjusted Load = Base Load x Slope Factor | Total Weight = Adjusted Load x Roof Area

Frequently Asked Questions

How much weight can a typical roof support from snow?
Most residential roofs are designed to support 20-40 psf (pounds per square foot) of snow load, depending on local building codes and climate zone. Older or flat roofs may have lower capacities. Check local building codes for specific requirements.
When should I remove snow from my roof?
Consider removal when snow load exceeds 20-25 psf, if you notice doors sticking, cracks in walls or ceilings, visible roof sagging, or when there are multiple layers of different snow densities. Wet, heavy snow and ice are more concerning than light, fluffy snow.
How do I estimate snow density?
Fresh snow is about 3-5 lb/ft³, settled snow 5-12 lb/ft³, packed or wind-blown snow 12-18 lb/ft³, and wet heavy snow 18-25 lb/ft³. Ice weighs about 56 lb/ft³. Real-world snow often has multiple layers of different densities.

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