Macomb County, MI Roof Snow Load - 20 psf
Macomb County, MI: your roof's ASCE 7 snow number, in plain English
Macomb County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. The physics-based figure alone would be 17.5 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 20 psf for flat and low-pitch roofs here, which is the number that actually governs.
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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Snow on Macomb County's roofs right now?
Macomb County in numbers
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#516 of 2,758
- Michigan rank#58 of 70
- Population886,175
- Annual snowfall, NOAA normal32.2 in.
- FIPS26099
Macomb County by the numbers
Nationally that's #516 out of 2,758 rated counties, the top 19%; within Michigan alone, Macomb County ranks #58 of 70. That's 11.7 psf below Michigan's own county-average design load of 31.7 psf.
Macomb County, FIPS 26099, is home to 886,175 people near 42.6716°N 82.9115°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
Macomb County's snowfall, most winters
32.2 in. a year: that's Macomb County's NOAA 1991-2020 snowfall normal, measured at MT CLEMENS ANG BASE, MI US (6.4 mi away). See the density guide.
Before you rely on Macomb County's number
Treat the Macomb 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. See the methodology guide.