SnowLoadCheck

Mercer County, WV Roof Snow Load - 20 psf

Mercer County, WV roof snow load, translated

Moderate
20 psf

A typical heated home in Mercer County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. The physics-based figure alone would be 14 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.

On a roof that means 44 in. of fresh snow, 16 in. once it packs down, or 4 in. of solid ice - three very different piles for the same load. 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.

Mercer County at a glance

Where Mercer County ranks

#5 of 34 West Virginia counties by design load, top 26% of 2,758 nationally - that's Mercer County's spot. Mercer County's figure lands almost exactly on West Virginia's own county-average of 20 psf.

FIPS 54055, population 57,524, centered near 37.4034°N 81.1065°W. ASCE 7's underlying ground snow load here is 20 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.

Mercer County: average annual snowfall

Mercer County sees about 23.9 in. of snow most winters, per the PRINCETON, WV US station's 1991-2020 NOAA normal. See the density guide.

Read this before you use Mercer County's figure

The figure above assumes the case ASCE 7-22 treats as typical: a heated, ordinary-occupancy home on a partially exposed site. Change any of those - exposure, heating, roof pitch, occupancy category - and the real design number moves.

A building permit needs the number at your exact address, not the county average - the free ASCE 7 Hazard Tool returns that from your coordinates in about a minute and produces a PDF a plan reviewer will accept. (How this figure is calculated.)