Mills County, IA Roof Snow Load - 20 psf
Mills County, IA roof snow load, translated
A typical heated home in Mills County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. Flat and low-pitch roofs in Mills County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 17.5 psf the ground-load formula alone would produce.
On a roof that means 44 in. of fresh snow, 16 in. once it packs down, or 4 in. of solid ice - three very different piles for the same load. Modern-code homes carry a load like this without issue; an older addition, a carport, or any flat-roofed section is where it is worth checking first.
Mills County, IA: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#1,033 of 2,758
- Iowa rank#75 of 99
- Population14,717
- Annual snowfall, NOAA normal19.6 in.
- FIPS19129
Where Mills County ranks
#75 of 99 Iowa counties by design load, top 37% of 2,758 nationally - that's Mills County's spot. 21.7 psf is Iowa's typical county figure - Mills County comes in 1.7 psf under it.
FIPS 19129, population 14,717, centered near 41.0337°N 95.6191°W. ASCE 7's underlying ground snow load here is 25 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.
Mills County: average annual snowfall
Mills County sees about 19.6 in. of snow most winters, per the HASTINGS 4NE, IA US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Mills County's figure
The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.
A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. See the methodology guide.