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Project No. JB-569 20 June 2006 Revised 18 October 2006 Page 14 We recommend concrete slab-on-grade floors, garage floors, and exterior flatwork be a minimum thickness of 4 inches. The actual slab thickness must be determined by the project structural engineer. Due to the expansive nature of the near surface soil, we recommend reinforcing the concrete slab-on-grade floors, garage tloor, and/or exterior flatwork with a minimum of either, (1) No. 4 reinforcing bars spaced at 18 inches on center, or (21 with an alternate steel reinforcement as required by the project structural engineer. In general, the steel reinforcement should be supported by concrete dobies to maintain the minimum requirement for clearance according to the latest UBC standard. The project structural engineer should determine the acceptable concrete cover. Crack control joints should be located as directed by the project structural engineer. ~ Recommendations presented in the American Concrete Institute manual should be complied with for all concrete placement and curing operations. Improper curing techniques and/or excessive slump (water-cement ratio) could cause excessive shrinkage, cracking or curling. Concrete slabs should be allowed to cure adequately before placing vinyl or other moisture sensitive floor coverings. 6.6 Drainage It is important that foundation soils not be allowed to become saturated during or after construction. Furthermore, surface water must not be allowed to pond adjacent to building foundations. To preclude drainage problems, we recommend continuous roof gutter for the proposed structures. It will be necessary to direct all water collected from roof downspouts into closed conduits that lead to acceptable discharge points away from the structures. In addition, we recommend that a subdrain system be installed around the perimeter of the buildings to prevent groundwater from saturating foundation soils. The subdrain should consist of a perforated, rigid, PVC pipe surrounded by a minimum of 12 inches of an approved, clean drain rock, wrapped completely in an approved geotextile fabric. The pipe should be installed with the holes facing down and sloped to drain at a minimum grade of 1 percent. The subdrain should be extended with solid pipe to an acceptable discharge point. Additional subdrains may be required as determined by the soils engineer during grading operations. Atypical subdrain is shown on Figure 10, subdrain Detail. Grades should be such that drainage is away from the structures. Water and sewer utility lines should be properly installed to avoid becoming possible sources ~orbmacher Engineering, Inc.