Plymouth County, MA Roof Snow Load - 21 psf
What ASCE 7 says about snow load in Plymouth County
That's Plymouth County's design roof snow load per ASCE 7-22, for a typical heated single-family home - the number a permit reviewer starts from.
Converted to something you can actually eyeball on a roof: about 46.2 in. of fresh powder, 16.8 in. once it settles and packs down, or just 4.2 in. if it's turned to 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.
Plymouth County at a glance
- Design roof snow load21 psf
- Ground snow load, ASCE 7 map30 psf
- National rank#390 of 2,758
- Massachusetts rank#11 of 14
- Population542,090
- Annual snowfall, NOAA normal37.9 in.
- FIPS25023
Where Plymouth County's figure sits nationally
Out of 2,758 rated US counties, Plymouth County sits at #390, the top 14% nationally - #11 of 14 within Massachusetts. That's 6.6 psf below Massachusetts's own county-average design load of 27.6 psf.
Near 41.9872°N 70.7419°W, FIPS 25023: Plymouth County counts 542,090 residents and a 30 psf map value, which the code's own factors turn into 21 psf.
How much it actually snows in Plymouth County
Most winters bring Plymouth County roughly 37.9 in. of snow - NOAA's normal at PLYMOUTH-KINGSTON, MA US, 2.4 mi off. (fresh vs. packed vs. ice explains why.)
Read this before you rely on it
Plymouth County's number above is ASCE 7-22's default case, not a custom calculation: ordinary residential occupancy, heated, sited on ground that's neither fully sheltered nor fully exposed. Any one of those changing - pitch, exposure, heating, occupancy - moves the real figure.
Nothing here substitutes for an address-level number. Get one free, in about a minute, from the ASCE 7 Hazard Tool using your own coordinates rather than Plymouth County's county-wide figure. See the methodology guide.