Lemhi County, ID Roof Snow Load - 10 psf
How much snow is too much for a roof in Lemhi County, ID?
10 psf: that's what ASCE 7-22 requires a typical heated home's roof in Lemhi County to carry. The physics-based figure alone would be 7 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 10 psf for flat and low-pitch roofs here, which is the number that actually governs.
Picture it, not just weigh it: 22 in. if it's fresh powder, 8 in. once it settles, or a mere 2 in. if it's ice. A modest addition to standard roof loading. Ordinary residential construction handles this without extra bracing.
Lemhi County in numbers
- Design roof snow load10 psf
- Ground snow load, ASCE 7 map10 psf
- National rank#2,013 of 2,758
- Idaho rank#8 of 9
- Population8,397
- Annual snowfall, NOAA normal22 in.
- FIPS16059
How Lemhi County compares
10 psf ranks #2,013 of 2,758 US counties with a mapped snow load (top 73%) - and #8 of 9 in Idaho. Idaho counties average 12.2 psf; Lemhi County runs 2.2 psf lower than that.
Population 8,397 (FIPS 16059), roughly 44.9285°N 113.887°W. The 10 psf ground snow load ASCE 7-22 maps here becomes 10 psf once the code's own design factors are applied.
Typical snowfall in Lemhi County, ID
NOAA's 30-year normal for Lemhi County: 22 in. of snow a year, from the SALMON-KSRA, ID US station. (fresh vs. packed vs. ice explains why.)
What this Lemhi 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.
Lemhi 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. Details: the calculation guide.