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Gradient, load intensity and eros.ian characteristics of slope MBtcrial. 1805.4Footings shall be designed an constructed in Allowable bearing capacity of the soil is not exceeded, and That differentia! settlement is minimized. The minimum Width offootings shall be 12 inches (305 nun) Footings in areas with expansive soils shall be designed In ac<:ordance with the provisions of Section 1805.8. 1805.4.11.1 Design loads, Footings shalJ be designed for the most unfavorable effects due to the combinations of loads specified in Section 1605.3. The dead load shall in- clued the weight of foundations" footings and overlying filJ. Reduced live loads, as specifted in Section 1607.9. Are permitted to be used in designing footings. 1805.4.12 Viblll10ry loads. Where machinery opera- tions or other vibrations are transmitted through the foundation, consideration shall be &iven in the footing design to prevent detrimental disturbances of the soil. 1 8OS.4.2 Concrete footings. The design, materials and c0n- struction of concrete footings shall comply with Sections 1805.42.1 through 1805.4.2.6 and the provisions ofCbap- tel' 1~.4.2. Exception: Where a specific design is not provided, coo- Crete footings supporting walls of/ight-frame construc- tion are permitted to be designed in accordance with Table 1805.4.2 1805.42.1 Concrete strength. Concrete in footings Shall have a specified compressive strength (fc) ofoot Less than 2,500 pounds per square inch (psi)(17 237 kPa) At 28 days. 1805.422 Reserved. SOILS AND FOUNDAAnONS ] 805.4.2.3 Plain concrete footings. The edge thickness Of plain coocretc footings supporting walls of other than Light-frame construction shall not be less that 8 inches (203 nun) where placed on soil. Exception: For plain concrete footings supporting Group R-3 occupancies. the ~e thickness is permit- ted to be 6 inches (152 nun),provided that the footing Does not extend beyond a distance greater that the Thic.knes.'l of the footing 00 either side of the supported Wall. 1805.4.2.4 Placement of concrete. Concrete footIngs Shall not be placed through water unless a tremie or other method approved by the building official is used, Whece placed under or in the presence of water" the concrete shall be deposited by approved means to ensure mini- mwn segregation of the mix and negligible turbulence of the water. 1805.4.2.5 Protection of concrete. Concrete footings shall be protected from freezing during depositing and foc 8 period ofnot less than five days thereafter. Water shall Not be allowed to flow through the deposited concrete. 1 &05.4.2.6 Forming of concrete. Concrete footings an: permitted to be east against the earth where, in the opin- ion of the building official, soil conditions do not require forming. Where forming is required, it shall be in accor- dance with Chapter 6 of ACI 318. 1805.4.3 Masonry-unit footings. The design, materials and construction of masonry-unit footings shall comply with Sections 1805.4.3.1 and 1805.4.3.2, and the provisions Of Chapter 21. Exception: Where a specific design is DOt provided, ma- sonry-unit footings supporting walls of light-frame con- Struction are permitted to b designed in accordance with Table lSOS.42. 1805.4.3.1 Dimc:zWoos, Masoory-unit footing shall be laid in Type M or S mortar complying with Section TABLE 1805.4.2 FOOTINGS SUPPORTING WALLS OF LIGHT-FRAME CONSTRUCfIONa.b.c.d WIDTIi OF nnCKNESS OF NUMBER OF FLOORS FOOTINGS FOOTING SUPPORTED BY TIlE FOOTINGS. (inches) (inches) I 12 6 2 15 6 3 18 8 For SI: I inch = 25.4 nun, I foot = 304.8 nun. &. Depth offootings sbalJ be in accordance with Section 18052. b. The ground UDder the floor is permitted to be excavated to the elevation of the top of the footing. c. Interior-ltud-bearing walls are permitted to be supported by isolated footinga. The footing width and length &hall be twice the width shown in this table, and footings shall be spaced not more than 6 Feet on center. d. For thickness of foundation walls, see Section 1805.5. c. Footings are permitted to support a roof in addition to the stipulated number of floors, Footings supporting roof only Shall be as required for supporting ODe floor. f Plain cooaete footings for Group R-3 occupancies are permitted to be 6 inches thick:.