SnowLoadCheck

Stillwater County, MT Roof Snow Load - 20 psf

What ASCE 7 says about snow load in Stillwater County

Moderate
20 psf

That's Stillwater County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. Flat and low-pitch roofs in Stillwater County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 17.5 psf the ground-load formula alone would produce.

Converted to something you can actually eyeball on a roof: about 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 in. if it's turned to ice. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.

Stillwater County in numbers

Where Stillwater County's figure sits nationally

Out of 2,758 rated US counties, Stillwater County sits at #1,115, the top 40% nationally - #13 of 29 within Montana. That's 1 psf above Montana's own county-average design load of 19 psf.

Near 45.6589°N 109.3817°W, FIPS 30095: Stillwater County counts 9,450 residents and a 25 psf map value, which the code's own factors turn into 20 psf.

How much it actually snows in Stillwater County

Most winters bring Stillwater County roughly 47.6 in. of snow - NOAA's normal at COLUMBUS, MT US, 5.6 mi off. (fresh vs. packed vs. ice explains why.)

Read this before you rely on it

Stillwater 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 Stillwater County's county-wide figure. Details: the calculation guide.