2010 W Alco Ave Unit #2 - Plan - Laserfiche WebLink

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Page 8 concern for the proposed development. However, without a proper treatment of the previous swimming pool backfill materials, substantial differential settlement of the previous swimming pool backfill materials may occur. With a proper treatment of the previous swimming pool backfill materials as recommended in this report, based on our experience, the conventional total settlement of ½ inch and a differential settlement of ¼ inch over a horizontal distance of 30 feet are anticipated for the proposed new structure and would occur during the construction stage. New (Interior) Building Slabs-on-Grade New (interior) building slabs-on-grade should be minimum 5 inches thick, reinforced with #4 re-bars at 12 inches on centers, or equivalent, placed at mid-height of the slab. New slabs should be underlain by a 2-inch thick layer of clean sand. For moisture sensitive floor areas, the new slabs should be underlain by a 10-mil polyethylene moisture barrier membrane (such as Visqueen). The moisture barrier membrane should be properly lapped and sealed at joints and around any breaks such as openings for utility conduits. Note: CAL Green Code, and/or other applicable codes/City’s requirements should govern and be followed. The entire slab-on-grade system including the capillary break / vapor/moisture retarder should be properly designed by the project civil /structural design engineer of record (but not by the geotechnical engineer) and reviewed and approved by the City prior to construction. New Exterior Slabs-on-Grade To reduce the potential for excessive cracking, new exterior concrete slabs-on-grade, if any, should be minimum 4 inches thick, provided with construction or weakened plane joints at frequent intervals (e. g., every 6 feet or less). Provision of a 2-inch thick layer of crushed rock, gravel, or clean sand to be placed beneath the slabs and/or reinforcement, such as #3 re-bars at 24 inches on-centers, or equivalent, placed at the mid-height of the slab should be considered. The subgrade soils for the exterior slabs should be properly re- compacted. Slab Subgrade Pre-Saturation The conventional pre-saturation of subgrade soils to minimum 140% of the optimum moisture content to minimum 24 inches deep is not considered necessary for this project. However, spraying with water should be performed prior to concrete pour. Other Recommendations for Reducing Slab Cracking While not a geotechnical issue, the potential for slab cracking may also be reduced by careful control of water/cement ratio and slump of concrete. The contractor should take 2010 W Alco Ave Unit #24/22/2025