Snow Load Calculator (ASCE 7-22)

Your details

The 50-year mean recurrence interval ground snow load for your site. Look up your value from ASCE 7-22 Figure 7.2-1 or the local building authority. In the US northeast and mountain states, values commonly range from 20 to 100 psf.
psf
Risk category per ASCE 7-22 Table 1.5-1. Most residential and commercial buildings are Category II. Hospitals, fire stations, and emergency shelters are Category IV.
How exposed the roof is to wind. Wind blows snow off exposed roofs (Ce < 1.0) and allows accumulation on sheltered roofs (Ce > 1.0). See ASCE 7-22 Table 7.3-1.
How much heat escapes through the roof to melt snow. Well-insulated roofs lose little heat and accumulate more snow. See ASCE 7-22 Table 7.3-2.
The pitch of the roof in degrees from horizontal. A 4:12 pitch equals about 18.4 degrees. Steeper roofs shed snow (Cs < 1). Enter 0 for a flat or low-slope roof.
degrees
Slippery surfaces shed snow at lower angles than rough surfaces per ASCE 7-22 Fig. 7.4-1.
If snow guards, parapets, or other obstructions prevent snow from sliding off, set Cs = 1.0 (no shedding credit). ASCE 7-22 Section 7.4.5.
Adds a 5 psf surcharge when pg is 20 psf or less, per ASCE 7-22 Section 7.10. Applies in areas where rain can saturate a thin snowpack.
Horizontal projection of the roof from eave to ridge. Used to compute total weight.
ft
Length of the roof parallel to the ridge. Used to compute total weight.
ft
Length of the upwind roof surface contributing to drift at a lower roof or parapet. Leave 0 to skip drift calculation. See ASCE 7-22 Fig. 7.7-1.
ft
Vertical distance between the upper and lower roof levels. The drift height cannot exceed this value minus the balanced snow height.
ft
Design roof snow load (ps)Moderate load
20

Final sloped-roof design load per ASCE 7-22

Flat roof snow load (pf)20
Slope factor (Cs)1
Snow density17.25
Equivalent snow depth13.9
Total roof snow weight24,000
Peak drift surcharge (pd)0
Drift width (w)0
Drift height (hd)0
Rain-on-snow surcharge0
1
Steep - most snow sheds<0.3Moderate shedding0.3-0.7Low/flat - snow accumulates0.7+

Design roof snow load: 20.00 psf

  • Your design roof snow load is 20.00 psf, which is considered moderate.
  • These are preliminary estimates based on ASCE 7-22. Always verify with a licensed structural or civil engineer before construction or renovation.

Next stepCompare this design load to your roof structure's rated capacity. If your roof is older or already strained, consult an engineer before heavy snowfall.

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