Morrow County, OR Roof Snow Load - 15 psf
Morrow County, OR roof snow load, translated
A typical heated home in Morrow County is designed to carry 15 pounds per square foot of snow on its roof, per ASCE 7-22. 10.5 psf is what the ground-load formula alone gives; Morrow County's 15 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 33 in. of fresh snow, 12 in. once it packs down, or 3 in. of solid ice - three very different piles for the same load. A meaningful design load. Most homes built to modern code handle it, but additions, carports, and flat-roofed sections are worth a second look.
Morrow County in numbers
- Design roof snow load15 psf
- Ground snow load, ASCE 7 map15 psf
- National rank#1,532 of 2,758
- Oregon rank#4 of 15
- Population12,360
- Annual snowfall, NOAA normal12.8 in.
- FIPS41049
Where Morrow County ranks
#4 of 15 Oregon counties by design load, top 56% of 2,758 nationally - that's Morrow County's spot. That's 3 psf above Oregon's own county-average design load of 12 psf.
FIPS 41049, population 12,360, centered near 45.4255°N 119.6023°W. ASCE 7's underlying ground snow load here is 15 psf before the code's exposure and importance factors bring it to the 15 psf design figure above.
Morrow County: average annual snowfall
Morrow County sees about 12.8 in. of snow most winters, per the HEPPNER, OR US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use Morrow 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. (How this figure is calculated.)