Design Criteria

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:

Commercial Buildings

Ultimate design wind speeds:
– Also refer to OSSC Sec 1609.1.1 Exceptions.

Risk Category 1 buildings and other structures:

  • Wasco, Sherman, Gilliam, North of latitude 45.5 degrees: 120 mph.
  • Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler County: 110 mph.

Risk category III and IV buildings:

  • Wasco, Sherman, Gilliam, North of latitude 45.5 degrees: 130 mph.
  • Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler County: 115 mph.

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.
  • Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler County: 115 mph.

One and Two Family Residential:

  • Wasco, Sherman, Gilliam, North of latitude 45.5 degrees: 18 psf or 95 mph 3 second gust;
  • Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler County: 15 psf or 85 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.
  • Wasco, Sherman, Gilliam South of latitude 45.5 deg & all of Wheeler County: 115 mph.

Snow:

Based on Snow Load Analysis for Oregon, 4th Edition.

Previously, snow loading was determined from a statewide map. The map has been discontinued in favor of a website where the latitude and longitude may be input, giving the ground snow load for that specific location.

Visit snowload.seao.org, input the latitude and longitude and click ‘Get Snow Load’.
The loading shown is the ground snow load, which may be reduced depending on the roof pitch, roof covering and exposure to wind. The roof snow load may not be reduced to less than 20 psf.

To convert latitude/longitudes to decimals as required in the SEAO website, refer to: https://www.fcc.gov/encyclopedia/degrees-minutes-seconds-tofrom-decimal-degrees

Frost Depth 24”

Climate Zone 2