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GYPSUM WALLBOARD Section 09250 15-1207 J. Fixture Enclosures: Provide 1 hour enclosures of 5/8 inch thick UL labeled wallboard around all fixtures in ceilings with one hour fire rating. K. Fiberboard Base/Tackboard: Apply vertically. Glue and nail to gypsum board backing with 5d nails at 12 inches o.c. at supports with nails dimpled, leaving minimum 1/8 inch gap between boards. Fill gap between boards with hardening -type patching compound such as "Fixall" with maximum hardening time of 1-1/2 hours. Allow material to dry for 24 hours. Tape and finish joints and nail depressions as specified for gypsum board application, leaving surfaces ready for priming and application of vinyl wall covering. L. Metal Furring Channels: Fasten to wall at 24 inches o.c. maximum. Position channels within 4 inches of floor and ceiling. Channel spacing not to exceed 24 inches o.c. At concrete and CMU applications attach channels with Hilti X -GN PDF (power driven fastener), 0.118 shank diameter with 1 inch minimum embedment. Two fasteners within 3 inches each end and two rows at 32 inches o.c., stagger 16 inches. Install per ICC Report ER -6196. Apply gypsum board to channels using 1 inch long U.S.G. Type S screws spaced 12 inches o.c. with horizontal abutting edges centered over clip screw flange. M. Interior Masonry and Concrete Walls: Apply adhesive directly to the back of the gypsum board or on the wall in continuous beads not more than 12 inches o.c. or daubs spaced not exceeding 12 inches o.c. each way. Beads shall not be less than 3/8 inch in diameter to provide continuous bond between the gypsum board and the wall surface. Daubs shall be 2 inches to 3 inches in diameter. Gypsum board shall be positioned 1/8 inch from the floor and provide a tight fit at abutting edges or ends. Do not slide the gypsum board. Use mechanical fasteners or temporary bracing to support gypsum board until adhesive sets. Delay the joint treatment until the gypsum board is firmly bonded. 3.05 FINISHING A. Gypsum Wallboard Finish Levels: 1. Level 0: No taping, finishing, or accessories required. 2. Level 1: All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. 3. Level 2: All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess compound. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level. 4. Level 3: All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. Provide one coat of high solids drywall primer prior to the application of any wall finishes. 5. Level 4: All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. Provide one coat of high solids drywall 1.1