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22.10 - Plain concrete in structures assigned to seismic design category C, D, E or F. <br /> 22.10.1- Structures assigned to Seismic Design Category C, D, E or F shall not have <br /> elements of structural plain concrete, except as follows: <br /> (a) Isolated footings of plain concrete supporting pedestals or columns are <br /> permitted, provided the projection of the footing beyond the face of the supported <br /> member does not exceed the footing thickness. <br /> (b) Plain concrete footing supporting walls are permitted, provided the footings have <br /> at least two continuous longitudinal reinforcing bars. Bars shall not be smaller <br /> than No. 4 and shall have a total area of not less than 0.002 times the gross <br /> cross-sectional area of the footing. A minimum of one bar shall be provided at <br /> the top and bottom of the footing. Continuity of reinforcement shall be provided <br /> at corners and intersections. <br /> Exception: In detached one and two-family dwellings three stories or less in <br /> height and constructed with stud bearing walls, plain concrete footings with at <br /> least two continuous longitudinal reinforcing bars not smaller than No. 4 are <br /> permitted to have a total area of less than 0.002 times the gross cross— <br /> sectional area of the footing. <br /> 20.08.120 CBC Section 1907.1 amended - Minimum Slab Provisions. <br /> Section 1907.1 is amended to read as follows: <br /> 1907.1 General. The thickness of concrete floor slabs supported directly on the ground <br /> shall not be less than 3% inches (89 mm). A minimum 10-mil (0.010 inch, .20mm) <br /> polyethylene moisture retarder with joints lapped not less than 6 inches (152 mm) shall <br /> be placed above a minimum of 4-inches (102 mm) of crushed or angular rock capillary <br /> moisture barrier or other approved equivalent methods and materials used to provide <br /> slab-stability and moisture protection of the interior environment of the building. The <br /> capillary moisture barrier material shall have a maximum particle size of 3/4-inch with no <br /> more than 10 percent smaller than 1/4—inch. In order to promote a more uniform curing <br /> of the slab and to provide protection for the polyethylene moisture retarder, a minimum <br /> of two-inches of fine clean sand shall be placed directly over the moisture retarder. As <br /> a minimum and in all cases where a slab is to be placed inside of a building, the slab <br /> shall be reinforced with not less than six inches by six inches ten gauge welded wire <br /> mesh or an approved alternate installed on approved supports at mid height of the <br /> concrete slab. <br /> Exception: A vapor retarder, sand and rock are not required: <br /> 1. For detached structures accessory to occupancies in Group R-3, such as <br /> garages, utility buildings or other unheated facilities. <br /> 2. For unheated storage rooms having an area of less than 70 square feet (6.5 m2) <br /> and carports attached to occupancies in Group R-3. <br />