St. Francois County, MO Roof Snow Load - 20 psf
St. Francois County, MO: your roof's ASCE 7 snow number, in plain English
St. Francois County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 14 psf is what the ground-load formula alone gives; St. Francois 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.
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. 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.
St. Francois County, MO: quick facts
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#692 of 2,758
- Missouri rank#13 of 115
- Population67,503
- Annual snowfall, NOAA normal8.7 in.
- FIPS29187
St. Francois County by the numbers
Nationally that's #692 out of 2,758 rated counties, the top 25%; within Missouri alone, St. Francois County ranks #13 of 115. That's 1.4 psf above Missouri's own county-average design load of 18.6 psf.
St. Francois County, FIPS 29187, is home to 67,503 people near 37.8107°N 90.4739°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
St. Francois County's snowfall, most winters
8.7 in. a year: that's St. Francois County's NOAA 1991-2020 snowfall normal, measured at FARMINGTON, MO US (3.7 mi away). See the density guide.
Before you rely on St. Francois County's number
Treat the St. Francois 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.)