1041 S Dennis St - Soils Report - Laserfiche WebLink

Home Browse Search

7 .7 .3 Footing Reinforcement Reinforcement for footings should be designed by the structural engineer based on the anticipated loading conditions. Footings for lightly loaded wood-frame structures that are supported in low expansive soils should have No. 4 bars. two top and two bottom. 7,8 CONCRETE, SLAB ON.GRADE Concrete slabs will be placed on undisturbed natural soils or properly compacted fill as outlined in Section 7.2. Moisture content of subgrade soils should be maintained near optimum moisture content. At the time ofthe concrete pour. subgrade soils should be firm and relatively unyielding. Any disturbed soils should be excavated and then replaced and compacted to a minimum of 90 percent relative compaction. Slabs should be designed to accommodate low expansive fill soils. The structural engineer should determine the minimum slab thickness and reinlorcing depending upon the expansive soil condition intended use. Slabs placed on low expansive soils should be at least 4 inches thick and have minimum reinforcement of No. 3 bars placed at mid- height of the slabs and spaced l8 inches on centers. in both directions. The structural engineer may require thicker slabs with more reinforcement depending on the anticipated slab loading conditions. lf moisture-sensitive floor covering is planned, a layer of open-graded gravel. at least 4 inches thick, should be placed below the concrete slab to form a capillary break. Altemately, moisture-proof membrane (such as l0-mil) may be utilized. The vapor barrier should be placed between sand layers (2 inches above and below) to protect the membrane from damage during construction. Gravel for use under a concrete floor slab should be clean. crushed rock that meets the gradation requirements presented below. Sieve Size Percentage linch I (X) % inch No. -l r0 0-t0 Dennis'l -01 90- I 00