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3987 Stanley <br />4 March 2017 (revised 4 August2017) <br />RECOMMENDATIONS <br />Environmental Noise Assessment <br />Page 4 <br />1. Single event noise from trains will limit the minimum STCl window rating because of the volume <br />of noise generated by train horns. To reduce single event noise from trains, it will be necessary <br />for all windows to be sound rated to meet the interior LmaX of 50 dB in bedrooms and 55 dB in <br />other living spaces. This report provides preliminary STC ratings based on assumed window sizes. <br />Final window size and STC rating should be verified once the design is finalized. <br />a. Assuming a standard 3 -coat stucco exterior assembly and 40%glazing in each room, <br />bedroom windows will need to be minimum STC 37 glazing (which incorporates a <br />laminated glass pane). Note window STC ratings are inclusive of the window frame. The <br />STC of the glazing alone is insufficient as framing can significantly degrade the overall <br />acoustic performance of the window assembly. <br />b. Assuming a standard 3 -coat stucco exterior assembly and 40% glazing in each room, <br />other living space windows will need to be minimum STC 32 glazing. <br />2. Noise levels at the project site exceed the Ld„ 60 dB guideline. To construct a residential project <br />in this noise environment, it will be necessary for all windows to be sound -rated to meet an <br />interior Ldp of 45 dB. <br />a. The STC rating to achieve the single event noise criteria in habitable rooms will meet the <br />STC requirements to meet the interior t�� of 45 d6. <br />3. The exterior noise level of Ldp 62 dB was measured 12 feet above the ground. For future <br />residents in backyard recreation areas, the receiver elevation is reduced by 6 feet. The future <br />homes should include solid fencing at least 6 feet high at each backyard. This fencing should <br />reduce the outdoor noise to comply with the Ldp 60 dB criteria. <br />Sound Transmission Class (STC) — Asingle-number rating standardized by ASTM and used to rate the sound insulation <br />properties of partitions. The STC rating is derived from laboratory measurements of a building element and as such is <br />representative of the maximum sound insulation. Increasing STC ratings correspond to improved airborne noise isolation. <br />