3333 NASSAU ST 2024-08-07 - Laserfiche WebLink

October 3, 2016 Single-Family Residence L&A Job No. 16-124 Page 15 portion of the foundations. For the latter, the foundations must be poured "neat" against undisturbed soils or backfilled with a clean, free-draining, compacted structural fill. We recommend that an equivalent fluid density (EFD) of 275 pcf(pounds per cubic foot) for the passive earth pressure be used for lateral resistance. The above passive pressure assumes that the backfill is level or inclines upward away from the foundations for a horizontal distance at least 1-1/2 times the depth of the foundations below the final grade. A coefficient of friction of 0.55 (ultimate value) between foundations and subgrade soils may be used. The above soil parameters are unfactored values, and a proper factor of safety should be used in calculating the resisting forces against lateral loads on the buildings. SLAB-ON-GRADE FLOORS Concrete,slab-on-grade floors, if used for the proposed residence, should be constructed on firm subgrade soil prepared as outlined in the SHE PREPARATION AND GENERAL EARTHWORK and the STRUCTURAL FILL sections of this report. Where moisture control is critical, the slab-on-grade floors should be placed on a capillary break which is in turn placed on the compacted subgrade. The capillary break should consist of a minimum four-inch-thick layer of clean, free-draining, 7/8-inch crushed rock, containing no more than 5 percent by weight passing the No. 4 sieve. A vapor barrier, such as a 6-mil plastic membrane, may be placed over the capillary break, as required, to keep moisture from migrating upwards. LIU & ASSOCIATES, INC.