What Is a Safe Snow Load for My Roof?
How to tell what your roof was designed to carry, warning signs of overload, and when to remove snow.
After a big storm the question is simple: is my roof okay? The answer comes from comparing the snow actually on the roof to the load the roof was designed for.
Find your design load
Your structural drawings or local building department list the design ground/roof snow load. If you don't have them, compute the ASCE 7 design load for your location and roof here as a reasonable benchmark, since most modern roofs are designed at least to the code value.
Estimate what's up there
Estimate the snow depth and whether it is light powder or dense, wet, settled snow. Multiply depth by density (powder ~5 pcf, wet ~20 pcf) to get the current load in psf, then compare to the design value.
Warning signs
Sagging ceilings, sticking doors, new cracks in drywall, and creaking are red flags. If the estimated load is approaching the design value or you see these signs, remove snow safely (rake from the ground) or call a professional. Never get on a loaded roof.
Get your design roof snow load in seconds with the free ASCE 7-22 calculator.
Open the calculator