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k%j KLEIN FELDER <br /> File No. 20-2182-24 <br /> February 20, 1990 <br /> concrete flatwork. We suggest the moisture-conditioned soils <br /> extend at least 2 to 3 feet beyond the building outlines to help <br /> insure moisture conditioning extends to the recommended depth <br /> beneath the buildings . If it is desired to further reduce the risk <br /> of heaving beneath floor slabs or if nonexpansive Engineered Fill <br /> is readily available, floor slabs can be underlain by a minimum of <br /> 12 inches of nonexpansive Engineered Fill over 12 inches of <br /> moisture-conditioned soils . Our recommendations for the <br /> preparation of the existing soils and the placement of Engineered <br /> Fill are contained in the "Site Preparation and Grading" section <br /> of this report. <br /> We recommend that a minimum 4-inch layer of gravel or coarse sand <br /> be placed beneath floor slabs in order to provide a capillary <br /> moisture break. If the nonexpansive Engineered Fill option is used <br /> and the fill consists of relatively clean coarse sand, this layer <br /> can be omitted as the nonexpansive Engineered Fill will act as a <br /> capillary moisture break. In areas where moisture transmission <br /> through slabs would be undesirable, the gravel or sand or <br /> nonexpansive Engineered Fill should be covered with a <br /> moistureproofing membrane such as "Moiststop, " or equivalent. Care <br /> should be exercised to avoid tearing, ripping or displacing the <br /> membrane during construction. If the membrane becomes torn or <br /> disturbed, it should be completely replaced or patched so that it <br /> will perform its intended function. An approximate 1-inch layer <br /> of damp sand should be placed over the membrane to help protect it <br /> during construction. The sand should be slightly moistened, but <br /> 8 <br />