Loudoun County, VA Roof Snow Load - 21 psf
Loudoun County, VA: your roof's ASCE 7 snow number, in plain English
Loudoun County's roofs are built to hold 21 psf of snow, the ASCE 7-22 figure a permit reviewer checks first.
In depth, not weight: that's roughly 46.2 inches of fresh, light snow, 16.8 inches of old, settled snow, or as little as 4.2 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.
Loudoun County at a glance
- Design roof snow load21 psf
- Ground snow load, ASCE 7 map30 psf
- National rank#393 of 2,758
- Virginia rank#1 of 110
- Population443,380
- Annual snowfall, NOAA normal21 in.
- FIPS51107
Loudoun County by the numbers
Nationally that's #393 out of 2,758 rated counties, the top 14%; within Virginia alone, Loudoun County ranks #1 of 110. 18.3 psf is Virginia's typical county figure - Loudoun County beats it by 2.7 psf.
Loudoun County, FIPS 51107, is home to 443,380 people near 39.0812°N 77.6389°W. Its 30 psf ground snow load figure is the map value; 21 psf is what a roof is actually designed for.
Loudoun County's snowfall, most winters
21 in. a year: that's Loudoun County's NOAA 1991-2020 snowfall normal, measured at WASHINGTON DC DULLES AP, VA US (13.5 mi away). See the density guide.
Before you rely on Loudoun County's number
Treat the Loudoun 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.