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publishing for any contractor or subcontractor bids. Written documentation indicating <br /> compliance with each attenuation/mitigation item will be provided to the City of Everett <br /> Housing and Community Development Program Manager in a timely manner during <br /> construction. The noise attenuation/mitigation includes: <br /> 1. No outdoor uses will occur above the second floor of the structure. <br /> 2. Type of mechanical ventilation provided: Ceramic Core Ventilators, located at <br /> courtyard side of residential units. <br /> 3. Walls: Combined STC rating for wall component: 38 <br /> a. Wall construction: 5/8" gypsum wallboard, 2 x 6 wood studs,%" plywood, <br /> 5/8" gypsum sheathing,%" rainscreen, fiber cement siding <br /> b. STC rating for walls: 40 <br /> c. Windows: %" glass, %" airspace, 3/16" glass <br /> d. STC rating for window type: 35 <br /> e. Percentage of walls composed of windows = 20% and doors = 0% <br /> 4. Exterior Wall: <br /> A standard exterior wall consisting of 2x6 stud, one layer of 5/8" GWB on the unit <br /> side,%" plywood, or exterior gyp, and siding on the outside, and the cavity filled with <br /> R-21 batt insulation has an STC40, and meets the criteria. <br /> In addition, careful attention should be given to sound leaks. Sound leaks can reduce <br /> the performance of a wall by more than 10 STC points if not treated. The following <br /> recommendations should be implemented to reduce sound transmission due to sound <br /> leaks. <br /> Notes: <br /> • Acoustic construction details are essential to the performance of any wall <br /> assembly. Appendix C contains a copy of ASTM C919: Standard Practice of <br /> Use of Sealants in Acoustical Applications. In type I construction, the first layer <br /> of 5/8" gypsum board on the unit side should be sealed top and bottom with <br /> resilient caulk, as well as around the junction boxes. <br /> • Window rough-in seams should be no greater than %", and all seams should <br /> be caulked with resilient caulking. <br /> • Seal, caulk, gasket or weather-strip all joints and seams to eliminate air <br /> leakage through these assemblies. This would include around window and <br /> doorframes; at penetrations through walls, and all other openings in the <br /> building envelope. <br /> 5. Windows: <br /> STC rated windows are recommended on the west and east facades (facade facing <br /> Broadway, and facade facing railroad tracks), and on the north and south facades with <br /> partial exposure to traffic on Broadway, and railroad tracks, as shown in the drawing <br /> below. <br /> Exhibit A <br /> Housing Hope Properties <br /> Page 6 of 7 <br />