ZIP Code 98581
Cowlitz County, Washington — Ryderwood
What This Means
Cowlitz County, Washington has a light ground snow load of 15 PSF per ASCE 7-22. At this level, most standard residential roofs are designed to handle the load without issue. However, flat or low-slope roofs should still be checked for drifting and sliding snow.
Snow Load Details
| ZIP Code | 98581 |
| County | Cowlitz |
| City | Ryderwood |
| State | Washington (WA) |
| Ground Snow Load | 15 PSF — Light |
| Classification Range | 1 - 20 PSF |
| Data Quality | Elevation estimated |
Source: ASCE 7-22 ground snow load polygons via ArcGIS
Roof Snow Load Calculator
ASCE 7-22 flat roof formula: pf = 0.7 × Ce × Ct × Is × pg
Your ground snow load (pg): 15 PSF
ⓘ Simplified estimate for flat roofs. Sloped roofs, drift zones, and unbalanced loads need additional calculations. Consult a structural engineer for final design.
Cowlitz County Snow Load Map
Counties colored by snow load classification. Gray = No Load, Blue = Light, Amber = Moderate, Orange = Heavy, Red = Extreme, Purple = Case Study.
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Frequently Asked Questions
What is the ground snow load for ZIP code 98581?
ZIP code 98581 is in Cowlitz County, Washington, with a ground snow load of 15 PSF, classified as light per ASCE 7-22.
Is my roof strong enough for snow in 98581?
With a light ground snow load of 15 PSF, standard residential construction typically handles this load, but verify with your local building code.
What county is ZIP code 98581 in?
ZIP code 98581 is in Cowlitz County, Washington (WA).