SnowLoadCheck

Louisa County, IA Roof Snow Load - 20 psf

Louisa County, IA: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Louisa County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 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.

In depth, not weight: that's roughly 44 inches of fresh, light snow, 16 inches of old, settled snow, or as little as 4 inches of solid ice - snow that heavy is rare here but ice from a freeze-thaw cycle adds up far faster than the depth suggests. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

Louisa County at a glance

Louisa County by the numbers

Nationally that's #1,093 out of 2,758 rated counties, the top 40%; within Iowa alone, Louisa County ranks #82 of 99. That's 1.7 psf below Iowa's own county-average design load of 21.7 psf.

Louisa County, FIPS 19115, is home to 10,630 people near 41.2182°N 91.257°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Louisa County's snowfall, most winters

35.5 in. a year: that's Louisa County's NOAA 1991-2020 snowfall normal, measured at WAPELLO, IA US (4.4 mi away). See the density guide.

Before you rely on Louisa County's number

Treat the Louisa County figure as a starting point, not a final answer: it assumes standard occupancy, a heated structure and a moderately sheltered site, per ASCE 7-22's own defaults. Exposed terrain, an unheated building or a steeper roof all shift the real number.

For a real application, skip the county number and go straight to the ASCE 7 Hazard Tool - enter your coordinates and it returns a site-specific figure a plan reviewer will recognize. (How this figure is calculated.)