SnowLoadCheck

Petroleum County, MT Roof Snow Load - 20 psf

What ASCE 7 says about snow load in Petroleum County

Moderate
20 psf

That's Petroleum County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. 17.5 psf is what the ground-load formula alone gives; Petroleum County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.

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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

Petroleum County, MT: quick facts

Where Petroleum County's figure sits nationally

Out of 2,758 rated US counties, Petroleum County sits at #1,302, the top 47% nationally - #24 of 29 within Montana. That's 1 psf above Montana's own county-average design load of 19 psf.

Near 47.1419°N 108.2266°W, FIPS 30069: Petroleum County counts 525 residents and a 25 psf map value, which the code's own factors turn into 20 psf.

How much it actually snows in Petroleum County

Most winters bring Petroleum County roughly 33.1 in. of snow - NOAA's normal at VALENTINE, MT US, 18.7 mi off. (fresh vs. packed vs. ice explains why.)

Read this before you rely on it

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