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<br />Gradieot. load interWty and erosion cbaracteristics of slope <br />MatciiaI. <br /> <br />1805.4Footings sbaJJ be designed an constnJcted in <br />Allowable bearing capacity of the soil is not exceeded. and <br />That ditIerentiaJ scttIement is minimized. The minimwn <br />Width offootings sball be 12 incbcs (305 mm) <br /> <br />Footings in areas with expansive soils shall be designed <br />In accordance with the provisions ofSectiooI805.8. <br /> <br />1805.4.11.1 Design loads. Footings sball be designed for <br />the molt unfavorable effects due to the combinatioos of <br />loads specified in Sectiool605.3. The dead load sbaU in- <br />clued the weight of foundations" footings and overlying <br />fiB. Reduced Uve Joads.IS spcci1lcd in SccIion 1607.9. <br />Arc permitted to be used in designing footings. <br /> <br />1805.4.1.2 Vibratory loads. Where machinery opera_ <br />tioos or other vibrations are transmitted through the <br />foundation. consideration shall be liven in the footing <br />design to prevent detrimeotal disturbances of the soil. <br /> <br />1805.4.2 Concme footings. The design. materials and c0n- <br />struction of concrete footings shall COIllply with Sections <br />1805.4.2.1 through 1805.4.2.6 and the provisions ofCbap- <br />tel' 1~.4.2. <br /> <br />Eueptioo: Where a specific design is DOt provided. c0n- <br />Crete footings supporting waUs oflight-thune construc- <br />tion are permitted to be designed in accordance with <br />Table 1805.4.2 <br /> <br />1805.4.2.1 Coocrctc strength. Concrete in f~ <br />Sbal1 have a speoified compressive sUeogtb (f"c) ofnot <br />Less than 2.500 pounds per square inch (PSi)(l7 237 kPa) <br />At 28 days. <br /> <br />1805.4.2.2 Rcscrved. <br /> <br />SOILS AND FOUNDAA nONS <br /> <br />J 805.4.2.3 Plain coocrete footiDgs. The edge tbiclcness <br />Of plain concrete footings supporting walls of other than <br />Light-ftame construction sbaU not be less that 8 inches <br />(203 mm) where placed on soil. ' <br />Exception: For plain concrete footings supporting <br />Group R-3 occupancies. the ed&e thickness is permit- <br />ted to be 6 inches (152 mm).provided that the footing <br />Docs not extend beyond a distance greater that the <br />~~mthef~~~s*mthe~ <br />Wall. <br />1805.4.2.4 Placement of concrete. Cooacte footings <br />Sba1J not be placed through water unless a tremie or other <br />method approved by the building official is used, Where <br />placed under- or in the pre&eIlCe of water" the concrete <br />shall be deposited by approved means to ensure mini- <br />mwn segregation of the mix and negligible turbulence of <br />the water. <br /> <br />1805.4.2.5 Protection ofconcrcte. Concrete footings <br />shall be Protected ftom freezing dwing depositing and for <br />a period of not less than five days thereafter. Water shall <br />Not be allowed to flow through the deposited coocrete. <br /> <br />1805.4.2.6 Forming of concrete. Concrete footings are <br />permitted to be east against the earth where, in the opin- <br />ion of the building officiaJ. soil conditions do not require <br />forming. Wbc:re fomUng Is required. it shaU be in accor- <br />dance with 0Iapter 6 of ACI 318. <br /> <br />1805.4.3 Masomy-unit footings. The design. materials <br />and construction of masonry-unit footings shall comply <br />with Sections 1805.4.3.1 and 1805.4.3.2. and the provisions <br />Of Chapter 21. <br /> <br />Exception: Where 8 specific design is not provided. ~ <br />soruy-unit footings supporting walls of light-frame con- <br />Struction are permitted to b designed in accordance with <br />Table 1~.4.2. <br /> <br />1805.4.3.1 Dimensions, Masonry-unit footing sbaJJ be <br />laid in Type M or S mortar complying with Section <br /> <br />TABLE 1805.4.2 <br />FOOTINGS SUPPORTING WAU.S OF LIGHT-FRAME CONSTRUCflONa.b.c.d <br /> <br /> WIDTII OF I nnCKNESS OF <br />NUMBER OF FLOORS FOOTINGS FOOTING <br />SUPPORTED BY TIlE FOOTINGS. (inches) (inches) <br />I 12 6 <br />2 15 6, <br />3 18 8 <br /> , <br /> <br />1 inch = 25.4 mm. 1 foot = 304.8 mm. <br />Depth offootings sbaU be in accordaoce with Section 1805.2. <br />The ground under the floor is permitted to be excavated to the elevation of the top of the footing. <br />Interior-lCud-beariog waUs are permitted to be supported by isolated footings. The footing width and length sha11 be twice <br />the width shown in this table, and footings shall be spaced not more than 6 Feet on center. <br />For thickness offoundation walls. see Section 1805.5. <br />Footings arc permitted to support a roof in additioo to the stipulated number of ftoors, Footings supporting roof only <br />SbaU be as required for supporting one floor. <br />Plain coocretc footings for Group R-3 occupancies are permitted to be 6 inches thick. <br /> <br />For SI: <br />a. <br />b. <br />c. <br /> <br />d. <br />e. <br /> <br />t: <br />