Seismic:
- Residential Seismic Zone ‘C’.
- Commercial buildings – site specific, to be determined by engineer.
Soil:
- Soil Bearing Pressure – 1,500 psf (unless documented otherwise by soils report)
Wind:
- Wasco, Sherman, Gilliam, North of latitude 45.5 degrees, 94.5 mph (3-second gust).
- Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler and Grant County – 84 mph (3-second gust).
- Exposure factor B, C or D, depending on specific location. Exposed areas adjacent to Columbia River, exposure D; Other exposed areas, exposure C; areas not exposed to excessive wind gusting, exposure B.
- Oregon Structural Specialty Code permits use of 1998 OSSC wind provisions (see OSSC Sec 1609.1.1, exception #5 & Sec 1609.1.1.2).
Snow: Based on Snow Load Analysis for Oregon, 3rd Edition, 2007.
Previously, snow loading was determined based on elevation. It has been changed in the new analysis to site specific, as shown in the Snow Load Analysis maps. Typically, Sherman, Gilliam, Wheeler and the East half of Wasco Co (including The Dalles, Dufur, Tygh Valley, Maupin) are 20-25 psf ground snow load, with exceptions at higher elevation locations. Grant County varies widely. Primarily, locations along the John Day (below Prairie City) and lower Middle Fork John Day rivers are 20-25 psf.
Roof snow loads are limited to a minimum 20 psf. Please feel free to contact our office at 541-298-4461 to determine the correct ground snow load.
The Snow Load Analysis booklet may be purchased at these locations, from Building Codes Division website:
http://www.cbs.state.or.us/external/bcd/codestandards.html#st
Frost Depth 24”
Climate Zone 2