4933 GLENWOOD AVE 2016-01-01 MF Import

Jordan Construction �� JN 00284 July 25, 2000 Page 5 All slabs-on-grade shouid be underlain by a capillary break or drainage layer consisting of a minimum 4-inch thickness of coarse, free-draining structural fili with a gradation similar to that discussed later in PERMANENT FOUNDATION AND RETAINING WALLS. As noted by the American Concrete Institute (ACI) in Section 3.2.3 of the Guides for Concrete Floor and Slab Structures, proper moisture protection is desirable immediately below any on-grade siab that will be covered by tile, wood, carpet, impermeable floor coverings, or any moisture-sensitive equipment or products. ACI also notes that vapor retarders, such as 6-mil visqueen, are typicaliy used. A vapor retarder �s defined as a material with a permeance of less than 0.3 US perms per square foot (ps� per hour, as determined by ASTM E 96. It is possible that concrete admixtures may meet this specification, a!' •ough the manufacturers of the admixtures should be consulted. However, if no potential for vapor passage through the slab is desired, a vapor barrier should be used. A vapor barrier, as defined by ACI, is a product with a water transmission rate of O.00' perms per square foot per hour when tesied in accordance with ASTM E 96. Reinforced membranes having sealed overiaps can meet this requirement. Additionally, ACI (Section 4.1.5) recommends that a minimum of 4 inches of compactible granuiar fill, such as crushed rock, should be placed over the vapor retarder or barrier for protection. Sand is not recommended by ACI for use as the protection layer. PERMANENT FOUNDATION AND RETA/NING WALLS Retaining walis backfilled on only one side should be designed to resist the lateral earth pressures imposed by the soil they retain. The foliowing recommended design parameters are for walls that restrain level backfill: Active Earth Pressura ' 350 pcf Passive Earth Pressure 350 pcf Coe�cient of Friction 0.40 Soii Unit Weight 140 pcf Where:(i)pcf is pounds per cub(c foot,and(ii)activo and passive oarth pressures are computed using the equivalent tluid pmssures. ' For a restrelned wall that cannot deflect at ieast 0.002 times its hcight,a uNfarm lateral pressure equal to 10 psf times the hef�ht of the wall should be added to the above active equivalent 8utd pressure. The vaiues given above are to be used to design permanent foundation and retaining walis only. The passive pressure given is appropriate for the depth of �evel structural fill placed in front of a retaining or foundation wall only. We recommend a safety factor of at least 1.5 for overturning and sliding, when using the above values to design the walls. Restrained wall soil parameters should be utilized for a distance of 1.5 times the wall height from corners in the walls. The design values given above do not include the effects of any hydrostatic pressures behind the walls and assume that no surcharges, such as those caused by slopes, vehicles, or adjacent foundations will be exerted on the walis. If these conditions exist, those pressures should be added � i ` J ��/i ; GEOTEGH CONSULTANTS,INC. `-��f /