Design Information
The County's Minimum Elevation is 1,000 feet and the Maximum Elevation is 14,152 feet. The following design elements must be considered for all projects in Siskiyou County.
- Requirement that California Design Professional seal and sign plans - A Case Study has established that the required flat roof snow loading (Pf) throughout Siskiyou County be of either 40 psf. or 60 psf.
- The snow loading listed in the California Building Code (when converted to Pg) exceeds the 50 psf listed under Section 2308.2.3 - Allowable loads, of the Conventional Light-Frame Construction Section of the Code. Therefore, Conventional Light-Frame Construction cannot be used in Siskiyou County. All structural plans and details must be submitted with California Licensed Professional seals & signatures. Buildings must be designed with psf flat roof snow load, with no reductions for slope are allowed. An equivalent ground snow loading of (40 psf = 54 psf, 60 psf = 73 psf) may be used to calculate roof loads with no reductions for slope.
- Roof design loads for site above 5,000 feet elevation - Must be obtained from the Building Division.
- Flat roof snow load below 5,000 feet elevations - McCloud, Mt. Shasta, Dunsmuir, Weed and Happy Camp, 60 pounds per square foot. All Other areas, 40 pounds per square foot. See the Roof Snow Load Bulletin webpage.
- Basic Wind Speed, V, - The basic, general wind speed design loading for Siskiyou County is - 95 mph V, Risk Category II, Exposure C, for most structures below 5000 feet as a minimum requirement.
- Minimum design wind loads are based upon the 2022 CBC, Sections 1604.A Wind Loads, 1609A.3 Basic design wind speed, 1609A.4.3 Exposure categories, and Figure 1609A.3(1) Basic Design Wind Speeds V map for Risk Category II Buildings and other structures and Chapter 26 Wind Loads ASCE/SEI 7-16.
- ASCE 7-10 defines the term V as the basic wind speed corresponding to a 3-sec gust speed at 33 ft. above the ground in Exposure Category C.
- Earthquake - the Seismic Design Category is determined by the Design Professional.
- Soils Site Class - Based on soils investigation
- Climate Zone 16 - for Energy compliance
- Frost Depth - 12 inch minimum