Snow Load Calculator

Residential roofs are typically designed to hold 20-40 psf (pounds per square foot) of snow load in most regions, though this varies by location. Areas with heavy snowfall may require roofs designed for 50-70 psf or more. Fresh snow weighs about 3.75 lbs per cubic foot, while wet snow can weigh up to 46.8 lbs per cubic foot.

Remove snow if it exceeds your roof's load capacity, if you notice signs of structural stress (sagging, cracking, noises), or if ice buildup is present. Leave a thin layer (1-2 inches) to avoid damaging roofing materials. Use a roof rake from the ground when possible, and never use sharp tools that could damage shingles.

Snow density varies greatly by type: fresh snow (60 kg/m³, 3.75 lb/ft³), damp fresh snow (110 kg/m³, 6.87 lb/ft³), settled snow (250 kg/m³, 15.61 lb/ft³), wind-packed snow (375 kg/m³, 23.41 lb/ft³), very wet snow (750 kg/m³, 46.82 lb/ft³), and ice (917 kg/m³, 57.25 lb/ft³). Ice is over 15 times denser than fresh snow.

Steeper roofs shed snow more effectively, reducing the load. The roof pitch factor adjusts the surface area: a 6:12 pitch (26.6°) increases the roof area by about 12% compared to the footprint. Very steep roofs (over 45°) may shed snow naturally, while flat or low-slope roofs accumulate more snow and require higher load ratings.

A thin layer of snow (up to 6 inches) provides insulation value and can reduce heating costs. However, deep snow adds significant weight and should be removed. Never allow snow to accumulate beyond your roof's load capacity, and always remove ice buildup immediately due to its high density and the risk of ice dams.