SnowLoadCheck

Jefferson County, IA Roof Snow Load - 20 psf

How much snow is too much for a roof in Jefferson County, IA?

Moderate
20 psf

20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Jefferson County to carry. Flat and low-pitch roofs in Jefferson County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 14 psf the ground-load formula alone would produce.

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.

Already snow on the roof in Jefferson County?

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Jefferson County in numbers

How Jefferson County compares

20 psf ranks #1,010 of 2,758 US counties with a mapped snow load (top 37%) - and #73 of 99 in Iowa. 21.7 psf is Iowa's typical county figure - Jefferson County comes in 1.7 psf under it.

Population 15,781 (FIPS 19101), roughly 41.0064°N 91.9666°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 Jefferson County, IA

NOAA's 30-year normal for Jefferson County: 21.7 in. of snow a year, from the FAIRFIELD, IA US station. (fresh vs. packed vs. ice explains why.)

What this Jefferson 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.

Jefferson 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.