Marion County, IN Roof Snow Load - 20 psf
Marion County, IN: your roof's ASCE 7 snow number, in plain English
Marion County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. Flat and low-pitch roofs in Marion County are actually governed by ASCE 7's §7.3.4 minimum of 20 psf, not the 14 psf the ground-load formula alone would produce.
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.
Marion County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map20 psf
- National rank#511 of 2,758
- Indiana rank#1 of 89
- Population981,628
- Annual snowfall, NOAA normal26.7 in.
- FIPS18097
Marion County by the numbers
Nationally that's #511 out of 2,758 rated counties, the top 19%; within Indiana alone, Marion County ranks #1 of 89. 19.3 psf is Indiana's typical county figure - Marion County beats it by 0.7 psf.
Marion County, FIPS 18097, is home to 981,628 people near 39.783°N 86.1358°W. Its 20 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
Marion County's snowfall, most winters
26.7 in. a year: that's Marion County's NOAA 1991-2020 snowfall normal, measured at CASTLETON 2 S, IN US (8.1 mi away). See the density guide.
Before you rely on Marion County's number
Treat the Marion 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.)