Perka: Roof Snow Load

Return to Perka Library Roof Snow Load Ask what each company’s engineers uses for a roof (not ground) snow load, which can vary greatly based on geography. All companies calculate roof snow load – perhaps differently – based on ground snow load maps developed by the American Society of Civil Engineers (ASCE). For example, assuming a standard 3/12 roof slope, an absolute minimum roof snow load in snowy areas is 20 lbs./square feet. Regionally, roof snow loads range from 5 to 10 lbs./square feet in lower Midwest. You should also discuss the topography of the building site with each company, as well as surrounding structures because they can have an impact on snow drifting on the roof.