Decatur County, IA Roof Snow Load - 20 psf
How much snow is too much for a roof in Decatur County, IA?
20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Decatur County to carry. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 14 psf the ground-load formula alone would give, and the code says use the larger one.
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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Decatur County, IA: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#1,157 of 2,758
- Iowa rank#90 of 99
- Population7,656
- Annual snowfall, NOAA normal28.5 in.
- FIPS19053
How Decatur County compares
20 psf ranks #1,157 of 2,758 US counties with a mapped snow load (top 42%) - and #90 of 99 in Iowa. 21.7 psf is Iowa's typical county figure - Decatur County comes in 1.7 psf under it.
Population 7,656 (FIPS 19053), roughly 40.7364°N 93.7846°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 Decatur County, IA
NOAA's 30-year normal for Decatur County: 28.5 in. of snow a year, from the LEON 6 ESE, IA US station. (fresh vs. packed vs. ice explains why.)
What this Decatur 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.
Decatur 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.