King County, WA Roof Snow Load - Case Study Area
What "Case Study" means for King County
ASCE 7's own snow load map has no single figure for King County: the terrain is complex enough that the code (§7.2) requires an elevation-specific study rather than a county-wide value. That is the map being accurate, not a data gap.
FIPS 53033, population 2,340,211. 386 US counties get this same case-study treatment; King County is one of them.
King County in numbers
- Population2,340,211
- Annual snowfall, NOAA normal3.6 in.
- FIPS53033
King County: average annual snowfall
King County sees about 3.6 in. of snow most winters, per the SNOQUALMIE FALLS, WA US station's 1991-2020 NOAA normal. See the density guide.
Read this before you use King 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.