Valley County, MT Roof Snow Load - 20 psf
How much snow is too much for a roof in Valley County, MT?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Valley County to carry. 17.5 psf is what the ground-load formula alone gives; Valley 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.
Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's 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.
Valley County, MT: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#1,160 of 2,758
- Montana rank#16 of 29
- Population7,434
- Annual snowfall, NOAA normal40.7 in.
- FIPS30105
How Valley County compares
20 psf ranks #1,160 of 2,758 US counties with a mapped snow load (top 42%) - and #16 of 29 in Montana. That's 1 psf above Montana's own county-average design load of 19 psf.
Population 7,434 (FIPS 30105), roughly 48.3499°N 106.6704°W. The 25 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Valley County, MT
NOAA's 30-year normal for Valley County: 40.7 in. of snow a year, from the GLASGOW INTL AP, MT US station. (fresh vs. packed vs. ice explains why.)
What this Valley County figure assumes
This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.
Valley County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. See the methodology guide.