How the estimate works
Weight per square foot equals depth in feet times density. Densities vary widely: freshly fallen snow can be around 5–8 lb/ft³, settled snow often 15–20, wind-packed drifts more, and wet spring snow 30 or higher. Ice is roughly 57 lb/ft³. The tool adds the snow and ice layers and, if you enter a roof area, multiplies to get total weight.
What the design load means
Buildings are designed for a roof snow load set by the code in force when they were built, often shown on truss tags, plans or permits. Drifts behind parapets, valleys and lower roofs next to taller ones can carry far more than the average. If the estimate approaches the design figure, call a qualified contractor or engineer — and never climb onto a loaded roof yourself.
When snow load becomes a claim
Sagging ceilings, cracked drywall at the ceiling line, doors that stick, bent trusses and collapsed outbuildings are common snow-load losses. Many policies cover collapse caused by the weight of ice, snow or sleet, subject to their terms. Our freeze, ice dam & snow load appraisal page explains how these claims are scoped.
Questions about this tool
Why does wet spring snow matter so much?
Rain or melt soaking into an existing snowpack can double its density without adding much depth, so the load rises even if the roof looks the same.
Where do I find my roof’s design load?
Check building plans, truss manufacturer tags in the attic, the original permit, or ask your city or county building department.