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Mr. Sam Roberto <br />Project BBXX -01 -1 19A <br />May 24, 2001 <br />Page 10 <br />It is also recommended that, for vapor retarders /barriers installed below a sand cushion, that <br />moisture vapor transmission tests be performed after the concrete slabs have cured, but before <br />flooring is installed. Flooring manufacturers typically recommend upper limits for moisture <br />vapor transmission that can be used to set schedules for flooring installation. <br />D.S. Construction Observations and Testing <br />D.5.a. Observations <br />We recommend having a geotechnical engineer observe all excavations related to subgrade <br />preparations, and footing, slab and pavement construction. The purpose of the observations is to <br />evaluate the competence of the materials exposed in the excavations, and the adequacy of <br />excavation oversizing. <br />D.5.b. Materials Testing <br />We recommend density tests be taken in all backfill and fill placed below footings, slabs and <br />pavements, beside foundation walls, and behind retaining walls. We also recommend slump, air <br />content and strength tests of Portland cement concrete. <br />D.5.c. Cold Weather Precautions <br />If site grading and construction is anticipated during cold weather, all snow and ice should be <br />removed from cut and fill areas prior to additional grading. No fill should be placed on frozen <br />subgrades. No frozen soils should be used as fill. <br />Concrete delivered to the site should meet the temperature requirements of ASTM Test Method <br />C 94. Concrete should not be placed on frozen subgrades. Concrete should be protected from <br />freezing until the necessary strength is attained. Frost should not be permitted to penetrate below <br />footings. <br />