SnowLoadCheck

Montgomery County, MD Roof Snow Load - 20 psf

How much snow is too much for a roof in Montgomery County, MD?

Moderate
20 psf

20 psf: that's what ASCE 7-22 requires a typical heated home's roof in Montgomery County to carry. 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.

Picture it, not just weigh it: 44 in. if it's fresh powder, 16 in. once it settles, or a mere 4 in. if it's ice. 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.

Montgomery County, MD: quick facts

How Montgomery County compares

20 psf ranks #509 of 2,758 US counties with a mapped snow load (top 18%) - and #3 of 21 in Maryland. 20.1 psf is Maryland's typical county figure - Montgomery County comes in 0.1 psf under it.

Population 1,082,273 (FIPS 24031), roughly 39.1374°N 77.2031°W. The 25 psf ground snow load ASCE 7-22 maps here becomes 20 psf once the code's own design factors are applied.

Typical snowfall in Montgomery County, MD

NOAA's 30-year normal for Montgomery County: 32.6 in. of snow a year, from the CLARKSBURG 2.1 NE, MD US station. (fresh vs. packed vs. ice explains why.)

What this Montgomery County figure assumes

This is a county-level reference figure for a typical heated home built to Risk Category II (ordinary residential), on a partially exposed lot - the assumptions ASCE 7-22 itself treats as the default case. A steeper roof, a fully exposed hilltop lot, an unheated structure, or a higher risk category all change the actual number.

Montgomery County's permit office wants an address-specific figure, not this county average - the ASCE 7 Hazard Tool is free, takes under a minute, and outputs a PDF most reviewers accept. See the methodology guide.