4935 GLENWOOD AVE 2016-01-01 MF Import

Jordan Construction JN 00284 July 25, 2000 Page 5 All slabs-on-grade should be underlain by a capillary break or drainage layer consisting of a minimum 4-inch thickness of coarse, free-draining structural fill with a gradation similar to that discussed later in PERMANEPlT FOUNDAT/ON AND RETA/NING 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 slab that will be covered by tile, wood, carpet, impermeable floor coverings, or any moisture-sensitive equipment or products. AC! also notes that vapor retarders, such as 6-mil visqueen, are typically used. A vapor retarder is defined as a material with a permeance of Iess 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, although 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 0.00 perms per square foot per hour when !ested in accordance with ASTM E 96. Reinforced membranes having sealed overlaps can meet this requirement. Additionally, ACI (Section 4.1.5) recommends that a minimum of 4 inches of compactible granular 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/N/NG WALLS Retaining watls backfilled on only one side should be designed to resist the lateral earth pressures imposed by the soil they retain. The following recommended design parameters are for walls that restrain level backfill: Active Earth Pressure' 350 pcf Passive Earth Pressure 350 pcf Coefficient of Friction 0.40 Soil Unit Weight 140 pcf Where:(i)pct ts pounds per cubic foot,and(il)active and passive aarth pressures are aomputed using the equivalent fluid pressures. 'For a restreined wall that cannot deflect at leaat 0.002 times Ity helght,a unlfortn laterel pressure equal to 10 pst times the height of the wall should be added to the above aetive equivalent fluid pressure. The values given above are to be used to design permanent foundation and retaining walls only. The passive pressure given is appropriate for the depth of level structural fill placed in front of a retaining or foundation wall only. We recommend a safety factor of at least 1.5 for overtuming 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 walls. If these conditions exist, those pressures should be added GEOTECH CONSULTANTS,INC. /�