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.

1. 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.  

2. Please note, the information provided below regarding revised Snow Loading Design requirements is the most current that has been made available to the County. Should the referenced Codes be modified by the State Building Standard Commission, the information below will be modified accordingly.

   As of January 1, 2026, Siskiyou County will be enforcing the new 2025 California Building Standards Code known as (California Code of Regulations, Title 24) of the California Code of Regulations, including the model codes adopted therein by reference.

   The Building Standards Commission has made specific changes to the California Building Code in regards how snow loads are assigned by area and how the resultant values are used to calculate the Building Design Snow Loads. These changes will apply to all building types of construction.

• The California Building Code Section 1608, with reference to Chapter 7 of ASCE 7, and the use of the ASCE 7 Hazard Tool therein to determine with reliability targeted (strength based) ground snow load values.

• The Residential Building Code Section R301.2.3 and Figure R301.2(3) Note 1 with reference to ASCE 7 Hazard Tool therein to determine with reliability targeted (strength based) ground snow load values.

• Site-specific case studies shall be determined in accordance with Chapter 7 of ASCE 7 and shall be approved by the building official.

 Updated 2026 Siskiyou County Building Design Criteria:

1. Snow Load ASCE 7, Hazard Tool and the Historic Case Study:

Siskiyou County will maintain the March 1,1993 historical case study data that established the basic minimum snow load values as assigned in specific areas without change.

(An equivalent ground snow loading of 54 psf (Pg) = 40 psf Pf) & 73 psf (Pg) = 60 psf (Pf) may be used to calculate flat roof snow loads with no reductions for slope.)

The approval and use of the Siskiyou Counties case study is according to CBC Sec. 1608.2 Ground Snow Loads.

Siskiyou County’s basic minimum flat roof snow load values (documented Case Study) will continue to be used in combination with the ASCE 7 Hazard Tool (ASCE Hazard Tool) to evaluate each building site. When the ASCE 7 Hazard Tool values are higher, the Engineer shall use these snow load values instead of the minimum county snow load values. Note that, regardless of the Hazard Tool site specific output, no values less than 60 Pf or 40 Pf will be accepted.

a. McCloud, Mt. Shasta, Dunsmuir, Weed and Happy Camp, 60 psf (Pf).

b. All Other areas, 40 psf (Pf).

c. All projects within Siskiyou County must have California Design Professional seal and sign plans 

The following is provided for use in completing the above-mentioned Hazard Tool:

The 2025 California Building Code (CBC) continues to use a four-tiered system for structural design risk categories, which align with those defined in the ASCE 7 standard (specifically ASCE 7-22 as adopted in the 2025 CBC). The categories are based on the potential consequences of failure and are essential for determining design loads for wind and seismic forces. 

The four risk categories are:

• Risk Category I: Buildings and structures that represent a low hazard to human life in the event of failure, such as agricultural storage facilities, minor storage buildings, and some temporary structures.
• Risk Category II: The default category for most buildings, encompassing those not classified as I, III, or IV. This includes typical residential buildings (homes), office buildings, and retail stores.
• Risk Category III: Buildings and structures that pose a substantial hazard to human life if they fail, including schools with a large occupant load, large assembly places, and non-essential public utility facilities.
• Risk Category IV: Essential facilities that are critical for post-disaster recovery or house highly sensitive operations. This includes hospitals, emergency operation centers, fire and police stations, and supporting utility structures for these facilities. ​​​​​​​

1. 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.    
2. Earthquake - the Seismic Design Category is determined by the Design Professional.
3. Soils Site Class - Based on soils investigation
4. Climate Zone 16 - for Energy compliance
5. Frost Depth -  12 inch minimum
6. Floodplain Management - GIS Map