Bristol County, MA Roof Snow Load - 21 psf
Bristol County, MA roof snow load, translated
A typical heated home in Bristol County is designed to carry 21 pounds per square foot of snow on its roof, per ASCE 7-22.
On a roof that means 46.2 in. of fresh snow, 16.8 in. once it packs down, or 4.2 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.
Bristol County at a glance
- Design roof snow load21 psf
- Ground snow load, ASCE 7 map30 psf
- National rank#386 of 2,758
- Massachusetts rank#10 of 14
- Population588,593
- Annual snowfall, NOAA normal30.8 in.
- FIPS25005
Where Bristol County ranks
#10 of 14 Massachusetts counties by design load, top 14% of 2,758 nationally - that's Bristol County's spot. That's 6.6 psf below Massachusetts's own county-average design load of 27.6 psf.
FIPS 25005, population 588,593, centered near 41.7486°N 71.0889°W. ASCE 7's underlying ground snow load here is 30 psf before the code's exposure and importance factors bring it to the 21 psf design figure above.
Bristol County: average annual snowfall
Bristol County sees about 30.8 in. of snow most winters, per the ROCHESTER, MA US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Bristol 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. Details: the calculation guide.