SnowLoadCheck

St. Clair County, MI Roof Snow Load - 20 psf

St. Clair County, MI: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

St. Clair County's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 17.5 psf is what the ground-load formula alone gives; St. Clair 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. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.

St. Clair County in numbers

St. Clair County by the numbers

Nationally that's #612 out of 2,758 rated counties, the top 22%; within Michigan alone, St. Clair County ranks #62 of 70. 31.7 psf is Michigan's typical county figure - St. Clair County comes in 11.7 psf under it.

St. Clair County, FIPS 26147, is home to 160,308 people near 42.9288°N 82.6689°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

St. Clair County's snowfall, most winters

46.6 in. a year: that's St. Clair County's NOAA 1991-2020 snowfall normal, measured at RICHMOND 4 NNW, MI US (7.3 mi away). See the density guide.

Before you rely on St. Clair County's number

Treat the St. Clair 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.