Iowa County, IA Roof Snow Load - 20 psf
How much snow is too much for a roof in Iowa County, IA?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Iowa County to carry. The physics-based figure alone would be 17.5 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 20 psf for flat and low-pitch roofs here, which is the number that actually governs.
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.
Iowa County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#1,003 of 2,758
- Iowa rank#71 of 99
- Population16,423
- Annual snowfall, NOAA normal28.1 in.
- FIPS19095
How Iowa County compares
20 psf ranks #1,003 of 2,758 US counties with a mapped snow load (top 36%) - and #71 of 99 in Iowa. That's 1.7 psf below Iowa's own county-average design load of 21.7 psf.
Population 16,423 (FIPS 19095), roughly 41.6839°N 92.0591°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 Iowa County, IA
NOAA's 30-year normal for Iowa County: 28.1 in. of snow a year, from the WILLIAMSBURG 1E, IA US station. (fresh vs. packed vs. ice explains why.)
What this Iowa 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.
Iowa 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.