Jefferson County, WI Roof Snow Load - 21 psf
What ASCE 7 says about snow load in Jefferson County
That's Jefferson County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from.
Converted to something you can actually eyeball on a roof: about 46.2 in. of fresh powder, 16.8 in. once it settles and packs down, or just 4.2 in. if it's turned to ice. Modern-code homes carry a load like this without issue; an older addition, a carport, or any flat-roofed section is where it is worth checking first.
Jefferson County, WI: quick facts
- Design roof snow load21 psf
- Ground snow load, ASCE 7 map30 psf
- National rank#423 of 2,758
- Wisconsin rank#64 of 72
- Population86,245
- Annual snowfall, NOAA normal42.3 in.
- FIPS55055
Where Jefferson County's figure sits nationally
Out of 2,758 rated US counties, Jefferson County sits at #423, the top 15% nationally - #64 of 72 within Wisconsin. That's 9.9 psf below Wisconsin's own county-average design load of 30.9 psf.
Near 43.0138°N 88.774°W, FIPS 55055: Jefferson County counts 86,245 residents and a 30 psf map value, which the code's own factors turn into 21 psf.
How much it actually snows in Jefferson County
Most winters bring Jefferson County roughly 42.3 in. of snow - NOAA's normal at LAKE MILLS WWTP, WI US, 7.7 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Jefferson County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.
Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Jefferson County's county-wide figure. Details: the calculation guide.