Smith County, TN Roof Snow Load - 10 psf
Smith County, TN roof snow load, translated
A typical heated home in Smith County is designed to carry 10 pounds per square foot of snow on its roof, per ASCE 7-22. 7 psf is what the ground-load formula alone gives; Smith County's 10 psf low-slope minimum (§7.3.4) beats it, so that figure is the one that governs on flat and low-pitch roofs.
On a roof that means 22 in. of fresh snow, 8 in. once it packs down, or 2 in. of solid ice - three very different piles for the same load. Standard residential construction handles a load this size without extra bracing; it is a modest addition on top of ordinary roof loading.
Got real snow on a Smith County roof right now?
Smith County in numbers
- Design roof snow load10 psf
- Ground snow load, ASCE 7 map10 psf
- National rank#1,903 of 2,758
- Tennessee rank#69 of 95
- Population20,783
- Annual snowfall, NOAA normal1.5 in.
- FIPS47159
Where Smith County ranks
#69 of 95 Tennessee counties by design load, top 69% of 2,758 nationally - that's Smith County's spot. Tennessee counties average 10.3 psf; Smith County runs 0.3 psf lower than that.
FIPS 47159, population 20,783, centered near 36.2717°N 85.9424°W. ASCE 7's underlying ground snow load here is 10 psf before the code's exposure and importance factors bring it to the 10 psf design figure above.
Smith County: average annual snowfall
Smith County sees about 1.5 in. of snow most winters, per the CARTHAGE, TN US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Smith 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.