A. Vertical chase requirements for mixed-use projects. To eliminate the need for future installation of ducts, pipes, and conduit on the exterior of a building, provisions shall be made at a maximum of 60 feet on center for one-hour rated vertical chases through residential floors to accommodate commercial utilities that must circuit to the roof. The chases shall have an interior clear dimension of 24 inches by 24 inches to accommodate a Class A exhaust hood for restaurant uses.
B. The building design of all new residential mixed use structures shall incorporate the following construction standards in order to reduce interior noise levels:
1. All penetrations of exterior walls shall include ½-inch airspace. This space shall be filled loosely with fiberglass insulation. The space shall then be sealed airtight on both sides of the wall with a resilient, non-hardening caulking or mastic;
2. The roof shall be finished with a minimum 7/16th-inch OSB or plyboard of equivalent surface weight, minimum 30 lb, felt paper and minimum 240 lb/square foot composition shingles or equivalent;
3. Skylights shall not be used unless they have an STC rating of 29 or better;
4. Windows shall have a minimum STC rating of 28;
5. Windows shall have an air filtration rate of less than or equal to 0.15 CFM/lin. ft, when tested with a 25 mile per hour wind per ASTM standards;
6. Sliding glass doors shall have a minimum STC rating of 29;
7. An HVAC system shall be installed which will provide minimum air circulation and fresh air supply requirements as specified in the Uniform Building Code (UBC); and
8. Gravity vent openings in attic space shall not exceed code minimum in size and number.
C. Alternative methods and materials may be used to achieve an interior noise level of 45 dB Ldn or less, subject to the approval by the planning director. (Ord. 2013-0020 § 1; Ord. 2013-0007 § 1)