1110 RAINIER AVE A DOMESTIC VIOLENCE SERVICES OF SNO CO 2018-01-01 MF Import

� Everott Nousing Authority May 16, 2012 � JN 120AQ Page 8 assume that the backfill will be well-compacted in lifts no thicker than 12 inches. The compaction of backfill near the walls should be accomplished wilh h�3nd-operated equipmen! to prevent the walls from being overloaded by the higher soil forces that occur during compaction. The section entitled General Earthwork and Structural Fill contains additional recommendations regarding the placement and compaction of structural fill behind retaining and foundalion �valis. The above recommendations are not intended to waterproof below-grade walls, or to prevent the formation of mold, mildew or fungi in interior spaces. Over time, the performance of subsurface drainage systems can degrade, subsurface groundwater flow patterns can change, and utilities can break or develop leaks. Therefore, waterprooting should be provided where future seepage through the walls is not acceptabie. This typically includes limiting cold-joincs and wail penetrations, and using bentoni,e panels or membranes on ihe outside of the walls. There are a variety of different waterproofing malerials and systems, which should be installed by an experienced coniractor familiar with the anticipated construction and subsurface conditions. Applying a ihin coat of asphalt emulsion to lhe outside face of a wall is not considered waterproofing, and wiil only help to reduce moisture generated from water vapoi or capillary action from seeping through the concrete. As with any project, adequate ventitation of basement and crawl space areas is important to prevent a build up of water vapor that is commonly lransmitted through concrete �valls 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 �valls. We recommend that you contact a specialty consultant if detailed recommendalions or specifications related to waterproofing design, or minimizing ihe potential for infestations of mold and mildew are desired. The General, Slabs-On-Grade, and Dreinage Consideretions sections should be reviewed for additional recommendations related to the control of groundwater and excess water vapor for tho anticipaled construction. SLABS-ON-GRADE The building floor at the western portion oF the southwestern building can be constructed as a slab- on-grade atop non-organic, firm native soil or on siructural fill. The subgrade soil must be in a firm, non-yielding condition at Ihe time o( slab conslruction or unders�ab fill piacement. Any soft areas encounlered should be excavated and replaced wiih select, imported struclural fill. Even where the exposed soils appear dry, water vapor will tend to naturaily migrate up�vard through the soil to the new consiructed space above it. This can aifect moislure-sensitive flooring, cause imperiections or damage to the slab, or simply alloa� excessive �vater vapor inlo Ihe space above fhe slab. All interior slabs-on-grade should be underlain by a capillary break or drainage layer consisting o( a minimum 4-inch lhickness of gravel or crushed rock lhat has a fines content (percent passing lhe No. 200 sieve) of less than 3 percent and a sand conlent (percent passing the No. 4 sieve) oi no more than 10 percenL As noted by the American Concrete Institute (ACI) in the Guides /or Concrefe Floor and Slab Structures, proper moisture protection is desirabie immediately beiow any on•grade slab that will be covered by tile, wood, carpet, impermeabie floor coverings, or any moisture-sensitivo equipment or products. ACI also notes ihat vapor retarders, such as 6-mil plastic sheeting, have beon used in ihe past, but are now recommending a minimum 10-mil thickness. A vapor retarder is defined as a material evith a permeance of less than 0.3 perms, as determined by ASTM E 96. It is possible that concrete admixtures may meet this specification, GEOTECH CONSULTANTS. INC.