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AMERICAN ENGINEERING TESTING, INC. AET Project No. 22-00012 <br /> or coverings on the concrete floor, and contribute to excessive humidity and possible microbial <br /> growth in the buildings. <br /> The vapor retarder should be placed in accordance with the recommendations given in Part 2, <br /> Section 302, of the Manual of Concrete Practice of the American Concrete Institute. Alternative <br /> methods of vapor retarder construction are described in the April 2001 issue of Concrete <br /> International. We also recommend that you contact the manufacturers of the specified floor <br /> coverings or coatings to see how they wish to have the vapor retarder installed, since their <br /> method may differ from the ACI methods. For additional recommendations on moisture and <br /> vapor protection of floor slabs, please refer to the standard sheet at the end of this report entitled <br /> Floor Slab Moisture/Vapor Protection. <br /> 6.5 Foundation Drainage <br /> Because the buildings will not have basements, it is our opinion that it is not necessary to <br /> construct a perimeter drain system around the foundations. However, if sand fill is used to <br /> prepare the building pads over clay subgrades, there is a potential for the sand fill to hold water. <br /> A perimeter drain system at foundation level, inside and outside the building, could remove this <br /> trapped water. There could be a substantial volume of water infiltrating the sand fill during <br /> construction until the buildings are enclosed, roofed and exterior surface drainage provided. <br /> Providing an efficient means of removing this water could aid in reducing the potential for <br /> construction delays or disturbance of the building pad soils. Furthermore, water from runoff or <br /> irrigation systems can infiltrate next to the foundation after construction. The perimeter drain <br /> system would help drain the water that infiltrates the exterior wall backfill. <br /> We recommend that the ground surface around each building be sloped away from the structure <br /> to promote surface runoff and reduce infiltration adjacent to the foundation walls. The surface <br /> should be sloped at least 6 inches in the first 10 feet. The roof drainage system should be <br /> designed to discharge away from the buildings. The landscaping next to the buildings should not <br /> have depressions filled with decorative rock or mulch, because this can cause ponding of water <br /> Page 17 of 28 <br />