SnowLoadCheck

Marshall County, IA Roof Snow Load - 20 psf

What ASCE 7 says about snow load in Marshall County

Moderate
20 psf

That's Marshall County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 17.5 psf the ground-load formula alone would give, and the code says use the larger one.

Converted to something you can actually eyeball on a roof: about 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 in. if it's turned to 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.

Snow on Marshall County's roofs right now?

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Marshall County in numbers

Where Marshall County's figure sits nationally

Out of 2,758 rated US counties, Marshall County sits at #782, the top 28% nationally - #53 of 99 within Iowa. That's 1.7 psf below Iowa's own county-average design load of 21.7 psf.

Near 42.0417°N 92.9814°W, FIPS 19127: Marshall County counts 40,392 residents and a 25 psf map value, which the code's own factors turn into 20 psf.

How much it actually snows in Marshall County

Most winters bring Marshall County roughly 25.3 in. of snow - NOAA's normal at MARSHALLTOWN, IA US, 3.3 mi off. (fresh vs. packed vs. ice explains why.)

Read this before you rely on it

Marshall County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.

Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Marshall County's county-wide figure. Details: the calculation guide.