Teton County, MT Roof Snow Load - 15 psf
Teton County, MT roof snow load, translated
A typical heated home in Teton County is designed to carry 15 pounds per square foot of snow on its roof, per ASCE 7-22. 10.5 psf is what the ground-load formula alone gives; Teton County's 15 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.
On a roof that means 33 in. of fresh snow, 12 in. once it packs down, or 3 in. of solid ice - three very different piles for the same load. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Teton County, MT: quick facts
- Design roof snow load15 psf
- Ground snow load, ASCE 7 map15 psf
- National rank#1,591 of 2,758
- Montana rank#25 of 29
- Population6,444
- Annual snowfall, NOAA normal45.9 in.
- FIPS30099
Where Teton County ranks
#25 of 29 Montana counties by design load, top 58% of 2,758 nationally - that's Teton County's spot. That's 4 psf below Montana's own county-average design load of 19 psf.
FIPS 30099, population 6,444, centered near 47.819°N 112.2817°W. ASCE 7's underlying ground snow load here is 15 psf before the code's exposure and importance factors bring it to the 15 psf design figure above.
Teton County: average annual snowfall
Teton County sees about 45.9 in. of snow most winters, per the SIMMS 1 NE, MT US station's 1991-2020 NOAA normal. 28.1 mi is a real gap between Teton County and its nearest reporting station, so local snowfall can diverge from this figure, especially near elevation changes. See the density guide.
Read this before you use Teton County's figure
The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.
A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.