Powder River County, MT Roof Snow Load - 21 psf
Powder River County, MT roof snow load, translated
A typical heated home in Powder River County is designed to carry 21 pounds per square foot of snow on its roof, per ASCE 7-22.
On a roof that means 46.2 in. of fresh snow, 16.8 in. once it packs down, or 4.2 in. of solid ice - three very different piles for the same load. 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.
Powder River County, MT: quick facts
- Design roof snow load21 psf
- Ground snow load, ASCE 7 map30 psf
- National rank#488 of 2,758
- Montana rank#4 of 29
- Population1,734
- Annual snowfall, NOAA normal29 in.
- FIPS30075
Where Powder River County ranks
#4 of 29 Montana counties by design load, top 18% of 2,758 nationally - that's Powder River County's spot. 19 psf is Montana's typical county figure - Powder River County beats it by 2 psf.
FIPS 30075, population 1,734, centered near 45.4089°N 105.5553°W. ASCE 7's underlying ground snow load here is 30 psf before the code's exposure and importance factors bring it to the 21 psf design figure above.
Powder River County: average annual snowfall
Powder River County sees about 29 in. of snow most winters, per the MOORHEAD 9 NE, MT US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Powder River 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. Details: the calculation guide.