4808 BELVEDERE AVE 2016-01-01 MF Import

Timberbuild Homes September 20, 2005 JN 05357 Page 7 The above recommendations are not intended to waterpraof below-grade walls, or to prevent the formation of mold, mildew or fur.�i in interl;�r spaces. Over time, the performance of subsurface drainage systems can degr�:ie, subsurface groundwater flow patterns can change, and utilititis can break or develop leaks. Therefore, waterproofing should be provided where future :;eepage through the walls is not acceptable. This typically includes limiting cold-joints armembranes on the outside of thie walls. There are a variety of diHerent waterproofing materials and systems, which should be installed by an axperienced contractor familiar with the anticipated construction and subsurface conditions. Applying a thin coat of asphalt emulsion to the outside face of a wall is not considered waterproofing, and will only Fielp to reduce moisture gen��rated from water vapor or capillary action from seeping through the concrete. As with any project, adequate ventilation of basement and crawl space areas is impurtant to prevent a build up of water vapor that is commonly transmitted through concrete walls from the surrounding soil, even when seepage is not present. This is appropriate even when waterproofing is applied to the outside of foundation and retaining walis. We recommend that you contact a specialty consultant if detailed recommendations or specifications related to waterproofing design, or minimizing the potential for infestations of mold and mildew are desired. The Genera/, S/abs•On•Grade, and Dreinage Considerations sections should be rev�ewed for additlonal recommendations related to the control of groundwater and excess water vapor for the anticipated construction. SLABS-�ON-GRADE The building floors can be constructed as slabs-on-grade atop non-organic, native sand or structural fill placed over this sand. The subgrade, soil must be in a firm, non-yielding condition the time of slab construction or underslab fill placement. Any soft areas encountered should excavated and replaced with select, imported structural fill. on at be Even where the exposed soils appear dry, water vapor will tend to naturally migrate upward through the soil to the new constructed space above it. All interior slabs-on-grade must be underlain by a capillary break or drainage layer consisti�g o( a minimum 4-inch thickness of gravel ar crushed rock that has a fines content (percent passing the No. 200 sieve) of less than 3 percent and a sand content (percent passing the No. 4 s�eve) of no more than 10 percent. This capillary break/drainage layer i� not nece�ssary if a;� underslab drainage system is installed. As noted by the American Concrete lnstitute (ACI) in th: Guides lor Concrefe Floor and Slab Structures, proper moisture protection is desiraUle immed.etely below any o�-grade slab that will be covered by tile, wood, carpet, impermeable floor coverings, or any moisture-sensitive equipment or products. ACI also notes that vapor retarders, such as 6-mil plastic sheeting, are typically used. A vapor retarder is defined as a material with a permeance of less than 0.3 US perms per square foot (ps� per hour, as determined by ASTM E 96. It is possible that concrete admixtures may meet this specificatfon, although the manufacturers of the admixtures should be consulted. Where plastic sheeting is used under slabs, joints should overlap by at least 6 inches and be sealed with adhesive tape. The sheeting should extend to the foundation walls for maximum vapor protection. If no potential for vapor passage through the slab is desired, a vapor 6arrier should be used. A vapor bamer, as defined by ACI, is a product with a water transmission rate of 0.00 perms per square foot per hour when tested in accordance with ASTM E 96. Reinforced membranes having sealed overlaps can meet this requirement. GEOTFCH CONSULTANTS. INC.