Prince William County, VA Roof Snow Load - 20 psf
What ASCE 7 says about snow load in Prince William County
That's Prince William County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from. ASCE 7's low-slope-roof minimum (§7.3.4) raises the governing figure to 20 psf - higher than the 17.5 psf the ground-load formula alone would give, and the code says use the larger one.
Converted to something you can actually eyeball on a roof: about 44 in. of fresh powder, 16 in. once it settles and packs down, or just 4 in. if it's turned to ice. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Prince William County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#545 of 2,758
- Virginia rank#13 of 110
- Population497,003
- Annual snowfall, NOAA normal21 in.
- FIPS51153
Where Prince William County's figure sits nationally
Out of 2,758 rated US counties, Prince William County sits at #545, the top 20% nationally - #13 of 110 within Virginia. 18.3 psf is Virginia's typical county figure - Prince William County beats it by 1.7 psf.
Near 38.7011°N 77.4796°W, FIPS 51153: Prince William County counts 497,003 residents and a 25 psf map value, which the code's own factors turn into 20 psf.
How much it actually snows in Prince William County
Most winters bring Prince William County roughly 21 in. of snow - NOAA's normal at WASHINGTON DC DULLES AP, VA US, 16.6 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Prince William County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.
Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Prince William County's county-wide figure. (How this figure is calculated.)