Suffolk County, NY Roof Snow Load - 20 psf
Suffolk County, NY roof snow load, translated
A typical heated home in Suffolk County is designed to carry 20 pounds per square foot of snow on its roof, per ASCE 7-22. §7.3.4's low-slope minimum of 20 psf is what actually governs on a flat or low-pitch roof here - higher than the 17.5 psf the base ground-load formula gives.
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. 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.
Suffolk County at a glance
- Design roof snow load20 psf
- Ground snow load, ASCE 7 map25 psf
- National rank#502 of 2,758
- New York rank#26 of 28
- Population1,535,909
- Annual snowfall, NOAA normal31.8 in.
- FIPS36103
Where Suffolk County ranks
#26 of 28 New York counties by design load, top 18% of 2,758 nationally - that's Suffolk County's spot. New York counties average 25.4 psf; Suffolk County runs 5.4 psf lower than that.
FIPS 36103, population 1,535,909, centered near 40.9436°N 72.6922°W. ASCE 7's underlying ground snow load here is 25 psf before the code's exposure and importance factors bring it to the 20 psf design figure above.
Suffolk County: average annual snowfall
Suffolk County sees about 31.8 in. of snow most winters, per the ISLIP LI MACARTHUR AP, NY US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Suffolk 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.