The construction methods and materials described in this section shall be considered to satisfy the noise level reduction standards set forth in Table 3.1-A, Land Use Compatibility Standards.
(1) Noise level reduction of 25 decibels (dB).
(a) If wood frame construction is used, all exterior stud walls shall have interior and exterior surfaces of an approved material at least as massive as one-half inch thick gypsum wallboard, and the intervening space shall contain fibrous thermal insulation at least three inches thick.
(b) The design for a habitable room shall be such that any exterior door or window can be kept closed when the room is in use. Means of ventilation shall be available to afford a minimum of two complete air changes per hour.
(c) Any air duct or connection to out-of-doors shall contain an interior sound absorbing lining acoustically equivalent at least to fiberglass duct line one inch thick and length greater than five times the diameter of the duct.
(d) The ceiling below an attic space shall include gypsum board or plaster at least one-half inch thick; fibrous thermal insulation at least three inches thick shall be laid between the ceiling joists.
(e) A forced air circulation system shall be provided that will give a minimum of two complete air changes per hour, of which at least one-fifth is fresh air.
(f) A ceiling or exhaust duct shall be provided with a bend in the duct such that there is no direct line of sight through the duct from outside to inside. The bend shall be lined with the equivalent of fiberglass duct liner one inch thick.
(g) There shall be no direct openings, such as mail slots, from the interior to the exterior of the building. All chimneys shall be provided with well-fitted dampers.
(h) Exterior hinged doors shall be solid-core construction. Jalousie windows shall not be permitted. The total area of glass windows and of any exterior door to a sleeping space shall not exceed 20% of the floor area of a room.
(i) Workmanship on doors and operable windows shall be such that the doors and windows are as close fitting as possible or weather stripping seals shall be incorporated on all edges to eliminate gaps. Air gaps and ratting shall be prevented.
(j) Masonry walls, if used, shall be at least equivalent in weight to six inch lightweight concrete blocks, at least one surface of which is painted or plastered.
(k) The roof deck shall weigh at least seven pounds per square foot, containing a solid core at least one and one-half inches thick.
(2) Noise level reduction 30 decibels (dB).
(a) Window glass shall be set in an elastomer gasket. Double glazing shall be installed, with an air space of at least three inches between the two panes of glass. Windows or dome skylights shall not be permitted, unless they have a sound transmission class of at least 30.
(b) The top-floor ceiling construction shall consist of plaster or gypsum board at least five-eighths inch thick supported on resilient clips or channels. A non-hardening caulking compound shall be provided around the entire perimeter of the suspended ceiling.
(c) The floor of the lowest room or area containing the uses to which those insulation requirements apply shall be a concrete slab, or should be similarly sealed otherwise against exterior noise.
(d) Masonry walls, if used, shall be at least equivalent in weight to eight inch lightweight concrete blocks, at least one surface of which shall be painted or plastered.
(e) The roof deck shall weigh at least 12 pounds per square foot. Wood roof sheathing shall be continuous and at least three-quarters inch thick.
(Ord. 21-97, passed - -1997; Ord. 10-2010, passed 7-26-2010)