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EFFECTIVE DATE: June 22, 2020 <br />BACKGROUND: <br />1.Section R401.4 of 2019 California Residential Code (CRC) requires a soils test to determine the soil's <br />characteristics if expansive soils are likely to be present. <br />2.Section 1803.5.11 of 2019 California Building Code (CBC) requires a "geotechnical investigationH for any <br />structure determined to be in Seismic Design Category C, D, E or Fin accordance with Section 1613. <br />3.Exception to Section 1803.2 states, "The building official shall be permitted to waive the requirement for a <br />geotechnical investigation where satisfactory data from adjacent areas is available that demonstrates an <br />investigation is not necessary for any of the conditions in Sections 1803.5.1 through 1803.5.6 and Sections <br />1803.5.10 and 1803.5.11." <br />POLICY: <br />Since majority of the County of Orange is located in Seismic Design Category D and due to the presence of expansive <br />soil in some county areas, we have developed the following policy to' comply with the 2019 CRC and CBC. <br />Geotechnical investigation report is required for all projects except as prescribed below. <br />Exception: <br />L One story room addition(s) to a single family dwelling up to 1,200 square feet of individual areas if it is <br />NOT located in liquefaction area. <br />2.One story room addition(s) to a single family dwelling up to 500 square feet of individual areas if It � <br />located in liquefaction area. <br />3.(a) Room addition(s) to a single family dwelling larger than 500 square feet of individual areas but not <br />more than 1,200 square feet located in liquefaction area shall require 4' of overexcavation. <br />(b)Detached accessory structure or single family dwelling larger than 500 square feet but not more than <br />1,200 square feet located in liquefaction area shall require 4' overexcavation. <br />4.One story detached accessory structure up to 1,200 square feet located in non-liquefaction area. <br />One story detached accessory structure up to 500 square feet located in liquefaction area. <br />5.Second story addition above existing first floor within the footprint of existing dwelling. <br />Excepted projects as described in item 5 above shall provide a letter from a California Licensed Geotechnical <br />Engineer or Civil Engineer practicing soil engineering stating the condition of existing foundation and supporting <br />Foundation Requirements for Residential Projects <br />and Accessory Structures <br />Page 18 of 108 <br />1011 W Second St <br />5/1/2025