Johnston County, OK Roof Snow Load - 10 psf
Johnston County, OK: your roof's ASCE 7 snow number, in plain English
Johnston County's roofs are built to hold 10 psf of snow, the ASCE 7-22 figure a permit reviewer checks first. 7 psf is what the ground-load formula alone gives; Johnston 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.
In depth, not weight: that's roughly 22 inches of fresh, light snow, 8 inches of old, settled snow, or as little as 2 inches of solid ice - snow that heavy is rare here but ice from a freeze-thaw cycle adds up far faster than the depth suggests. This is a modest add-on to standard roof loading - ordinary residential construction carries it without extra bracing.
Johnston County at a glance
- Design roof snow load10 psf
- Ground snow load, ASCE 7 map10 psf
- National rank#1,994 of 2,758
- Oklahoma rank#63 of 77
- Population10,293
- Annual snowfall, NOAA normal2 in.
- FIPS40069
Johnston County by the numbers
Nationally that's #1,994 out of 2,758 rated counties, the top 72%; within Oklahoma alone, Johnston County ranks #63 of 77. That's 1 psf below Oklahoma's own county-average design load of 11 psf.
Johnston County, FIPS 40069, is home to 10,293 people near 34.3135°N 96.6543°W. Its 10 psf ground snow load figure is the map value; 10 psf is what a roof is actually designed for.
Johnston County's snowfall, most winters
2 in. a year: that's Johnston County's NOAA 1991-2020 snowfall normal, measured at TISHOMINGO NATL WR, OK US (7.4 mi away). See the density guide.
Before you rely on Johnston County's number
Treat the Johnston County figure as a starting point, not a final answer: it assumes standard occupancy, a heated structure and a moderately sheltered site, per ASCE 7-22's own defaults. Exposed terrain, an unheated building or a steeper roof all shift the real number.
For a real application, skip the county number and go straight to the ASCE 7 Hazard Tool - enter your coordinates and it returns a site-specific figure a plan reviewer will recognize. See the methodology guide.