Charleston County, SC Roof Snow Load - 5 psf
Charleston County, SC roof snow load, translated
A typical heated home in Charleston County is designed to carry 5 pounds per square foot of snow on its roof, per ASCE 7-22. The physics-based figure alone would be 3.5 psf, but ASCE 7's own low-slope minimum (§7.3.4) sets a floor of 5 psf for flat and low-pitch roofs here, which is the number that actually governs.
On a roof that means 11 in. of fresh snow, 4 in. once it packs down, or 1 in. of solid ice - three very different piles for the same load. This is a modest add-on to standard roof loading - ordinary residential construction carries it without extra bracing.
Charleston County, SC: quick facts
- Design roof snow load5 psf
- Ground snow load, ASCE 7 map5 psf
- National rank#2,082 of 2,758
- South Carolina rank#36 of 46
- Population431,001
- Annual snowfall, NOAA normal0.3 in.
- FIPS45019
Where Charleston County ranks
#36 of 46 South Carolina counties by design load, top 75% of 2,758 nationally - that's Charleston County's spot. That's 3.8 psf below South Carolina's own county-average design load of 8.8 psf.
FIPS 45019, population 431,001, centered near 32.8005°N 79.9425°W. ASCE 7's underlying ground snow load here is 5 psf before the code's exposure and importance factors bring it to the 5 psf design figure above.
Charleston County: average annual snowfall
Charleston County sees about 0.3 in. of snow most winters, per the GIVHANS FERRY 2 ESE, SC US station's 1991-2020 NOAA normal. 28 mi is a real gap between Charleston County and its nearest reporting station, so local snowfall can diverge from this figure, especially near elevation changes. See the density guide.
Read this before you use Charleston 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. See the methodology guide.