SnowLoadCheck

Fairfax city, VA Roof Snow Load - 20 psf

Fairfax city, VA: your roof's ASCE 7 snow number, in plain English

Moderate
20 psf

Fairfax city's roofs are built to hold 20 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 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.

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. 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.

Fairfax city, VA: quick facts

Fairfax city by the numbers

Nationally that's #900 out of 2,758 rated counties, the top 33%; within Virginia alone, Fairfax city ranks #50 of 110. Virginia counties average 18.3 psf; Fairfax city runs 1.7 psf higher than that.

Fairfax city, FIPS 51600, is home to 26,340 people near 38.8532°N 77.299°W. Its 25 psf ground snow load figure is the map value; 20 psf is what a roof is actually designed for.

Fairfax city's snowfall, most winters

18.5 in. a year: that's Fairfax city's NOAA 1991-2020 snowfall normal, measured at VIENNA, VA US (2.7 mi away). See the density guide.

Before you rely on Fairfax city's number

Treat the Fairfax city 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. Details: the calculation guide.