Mahaska County, IA Roof Snow Load - 20 psf
How much snow is too much for a roof in Mahaska County, IA?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Mahaska County to carry. 14 psf is what the ground-load formula alone gives; Mahaska 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.
Mahaska County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#934 of 2,758
- Iowa rank#62 of 99
- Population22,034
- Annual snowfall, NOAA normal30 in.
- FIPS19123
How Mahaska County compares
20 psf ranks #934 of 2,758 US counties with a mapped snow load (top 34%) - and #62 of 99 in Iowa. 21.7 psf is Iowa's typical county figure - Mahaska County comes in 1.7 psf under it.
Population 22,034 (FIPS 19123), roughly 41.3308°N 92.6364°W. The 20 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.
Typical snowfall in Mahaska County, IA
NOAA's 30-year normal for Mahaska County: 30 in. of snow a year, from the MONTEZUMA 1 W, IA US station. (fresh vs. packed vs. ice explains why.)
What this Mahaska 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.
Mahaska 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.