Washington County, PA Roof Snow Load - 20 psf
Washington County, PA: your roof's ASCE 7 snow number, in plain English
Washington 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. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.
Washington County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#582 of 2,758
- Pennsylvania rank#30 of 38
- Population210,434
- Annual snowfall, NOAA normal31.9 in.
- FIPS42125
Washington County by the numbers
Nationally that's #582 out of 2,758 rated counties, the top 21%; within Pennsylvania alone, Washington County ranks #30 of 38. 20.9 psf is Pennsylvania's typical county figure - Washington County comes in 0.9 psf under it.
Washington County, FIPS 42125, is home to 210,434 people near 40.2°N 80.2521°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.
Washington County's snowfall, most winters
31.9 in. a year: that's Washington County's NOAA 1991-2020 snowfall normal, measured at WASHINGTON 3 NE, PA US (3.6 mi away). See the density guide.
Before you rely on Washington County's number
Treat the Washington 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.