Lancaster County, PA Roof Snow Load - 21 psf

How much snow is too much for a roof in Lancaster County, PA?

Picture it, not just weigh it: 46.2 in. if it's fresh powder, 16.8 in. once it settles, or a mere 4.2 in. if it's ice. This is a meaningful design load - most modern-code homes handle it fine, though an addition, a carport or a flat-roofed section can be a weak spot.

Lancaster County, PA: quick facts

• Design roof snow load21 psf
• Ground snow load, ASCE 7 map30 psf
• National rank#389 of 2,758
• Pennsylvania rank#6 of 38
• Population563,293
• Annual snowfall, NOAA normal21.4 in.
• FIPS42071

How Lancaster County compares

21 psf ranks #389 of 2,758 US counties with a mapped snow load (top 14%) - and #6 of 38 in Pennsylvania. That's 0.1 psf above Pennsylvania's own county-average design load of 20.9 psf.

Population 563,293 (FIPS 42071), roughly 40.042°N 76.2502°W. The 30 psf ground snow load ASCE 7-22 maps here becomes 21 psf once the code's own design factors are applied.

Typical snowfall in Lancaster County, PA

NOAA's 30-year normal for Lancaster County: 21.4 in. of snow a year, from the LANCASTER 2NE FLTR PLT, PA US station. (fresh vs. packed vs. ice explains why.)

What this Lancaster 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.

Lancaster 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. (How this figure is calculated.)