Washington County, IA Roof Snow Load - 20 psf
What ASCE 7 says about snow load in Washington County
That's Washington County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. 14 psf is what the ground-load formula alone gives; Washington County's 20 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.
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 Washington County's roofs right now?
Washington County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#929 of 2,758
- Iowa rank#61 of 99
- Population22,631
- Annual snowfall, NOAA normal25.2 in.
- FIPS19183
Where Washington County's figure sits nationally
Out of 2,758 rated US counties, Washington County sits at #929, the top 34% nationally - #61 of 99 within Iowa. 21.7 psf is Iowa's typical county figure - Washington County comes in 1.7 psf under it.
Near 41.3294°N 91.7251°W, FIPS 19183: Washington County counts 22,631 residents and a 20 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in Washington County
Most winters bring Washington County roughly 25.2 in. of snow - NOAA's normal at WASHINGTON, IA US, 3.4 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Washington 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 Washington County's county-wide figure. (How this figure is calculated.)