Davis County, IA Roof Snow Load - 20 psf
Davis County, IA roof snow load, translated
A typical heated home in Davis County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 14 psf the base ground-load formula gives.
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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Davis County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#1,120 of 2,758
- Iowa rank#86 of 99
- Population9,193
- Annual snowfall, NOAA normal24.2 in.
- FIPS19051
Where Davis County ranks
#86 of 99 Iowa counties by design load, top 41% of 2,758 nationally - that's Davis County's spot. That's 1.7 psf below Iowa's own county-average design load of 21.7 psf.
FIPS 19051, population 9,193, centered near 40.7481°N 92.4103°W. ASCE 7's underlying ground snow load here is 20 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.
Davis County: average annual snowfall
Davis County sees about 24.2 in. of snow most winters, per the BLOOMFIELD, IA US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Davis 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. (How this figure is calculated.)