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Geotechnical Engineering Investigation Page 16 of 24 New Residential Subdivision 2706 Pock Lane Stockton, CA 95205 March 30, 2021 CTE Job # 25-1097G 5.4 Concrete Slabs-On-Grade For lightly loaded concrete slabs on ground, we recommend minimum five-inch thick slabs-on- grade with minimum slab reinforcement of#4 reinforcing bars placed on 24-inch centers, each way, at mid-slab height. Slabs-on-grade subject to automobile or truck traffic should be a minimum of 5.5" thick and should contain a minimum slab reinforcement of#4 reinforcing bars placed on 24-inch centers, each way, at mid-slab height. The recommended Class II aggregate base layer thickness depends on the finish grade materials present following mass excavation/grading and or treatment. It is recommended that concrete slabs to be installed in proposed buildings areas be founded on a 4 inch thick layer of Class II aggregate base where lime treated soils are present. A minimum 8 inch layer of Class II aggregate base is recommended over moisture treated and compacted native soils. If elastic design is utilized for slabs-on-grade, a modulus of subgrade reaction (k) value of 90 pounds per cubic inch (pci) is considered suitable for the anticipated subgrade materials. If a minimum four-inch thick layer of Class 2 aggregate base is placed beneath slabs, then the design k value may be increased to 100 pci. A value of 125 pci is considered appropriate in lime-treated areas. In moisture sensitive floor areas,a vapor retarder of at least ten-mil thick plastic sheeting overlying a 4-inch layer of consolidated aggregate (minimum Sand Equivalent of 30) or gravel should be installed, or 6 inches of Class II aggregate base. A two-inch layer of clean sand material could be placed above the plastic sheeting to protect the membrane during steel and concrete placement, otherwise the membrane should be otherwise protected and/or repaired before concrete placement. It should be noted that CTE is not a waterproofing or water intrusion specialty consultant and the recommendation herein are considered typical. If the proposed building improvements, floor coverings, or usage are especially sensitive to moisture intrusion, a qualified specialty consultant could be retained for additional recommendations.