B. Sequencing: Schedule installation to keep sheathing exposure to UV within the manufacturer s recommended limits.

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1 SECTION GYPSUM SHEATHING PART 1 - GENERAL 1.1 SUMMARY A. Section Includes: 1. Exterior GMF gypsum sheathing. 2. Joint treatment materials. 3. Panel and penetration joint and fastener treatment. 4. Supplementary components and accessories necessary for a complete installation whether or not such items are indicated on the Drawings or included in the Specifications. 1.2 SECTION REQUIREMENTS A. Coordination: 1. Where items are installed or applied as part of fire-resistance-rated or STC-rated assemblies, items must be identical those products tested and listed as part of the selected UL or GA fire resistance and sound control system design designation. 2. Coordinate sheathing delivery with installation to minimize storage periods at the site. 3. Coordinate sheathing installation with installation of materials installed over sheathing so sheathing is not exposed to precipitation or left exposed at end of the workday when rain is forecast. B. Sequencing: Schedule installation to keep sheathing exposure to UV within the manufacturer s recommended limits. C. Submittals: Product Data and Samples. PART 2 - PRODUCTS 2.1 GMF GYPSUM SHEATHING A. Application: Installed outside of building wall framing members; serves as the substrate for exterior wall finishes. B. Description: Gypsum-based commercial exterior sheathing conforming to ASTM C C. Products: 1. Basis of Design Product: Design is based on the following. a. DensGlass Sheathing manufactured by GP Building Products. GYPSUM SHEATHING

2 2. Acceptable Products: Other acceptable comparable products are limited to one of the following. a. GlasRoc Sheathing manufactured by CertainTeed Corp. b. Gold Bond e 2 XP Extended Exposure Sheathing manufactured by National Gypsum Co. c. SECUROCK Glass-Mat Sheathing Panels manufactured by USG Corp. D. Items must conform to the following: 1. Minimum Size: Provide at least 4-foot by 8-foot sheets. 2. Thickness: 5/8-inch. 3. Edges: Tapered long edges and square ends. 4. Facers: Heat-cured, acrylic-coated, fiberglass mat on the face side, back side, and around long edges. Water repellent face and backing papers are not permitted. E. Joint Treatment Materials: 1. Joint Tape: a. Glass Mesh Tape: Provide 4-inch wide, alkali-resistant, polymer-coated, glassfiber mesh tape supplied, required, recommended, approved, or accepted by the manufacturer. b. Seam Seal Tape: 40-mil thick self-adhering, rubberized asphalt/polyethylene flexible flashing tape. 1) Acrylic-coated polypropylene tape is not permitted. 2) Glass mesh tape applied without sealant is not permitted. c. Products: 1) Basis-of-Design Product: Design is based on the following. a) Perm-A-Barrier Wall Flashing manufactured by W.R. Grace & Co. 2) Acceptable Manufacturers: Other acceptable sources of comparable products are limited to the following, contingent on demonstrated conformance to the specified requirements, including the item description above. a) CETCO, Inc. b) The Henry Co. d. Seam Seal Tape Primer: Perm-A-Barrier WB Primer water-based primer manufactured by W.R. Grace & Co. 2. Tape Bonding Materials: a. Joint Sealant: Provide low modulus single-component sealant specified in Section , unless otherwise supplied, required, recommended, approved, or accepted by the manufacturer. 2.2 ACCESSORIES A. Screw Fasteners: Provide inch shank diameter (#8-32 UNC) by at least 1-1/4 inch long stainless steel, bi-metal, duplex anti-corrosive steel, 3-coat anti-corrosive steel, or ceramic-coated anti-corrosive steel Philips bugle head, self- piercing or self-drilling (as applicable) screw fasteners specified in Section GYPSUM SHEATHING

3 B. Other Accessories: Provide other accessories and similar secondary items supplied, required, recommended, or accepted by the manufacturer. 2.3 PANEL AND PENETRATION JOINT TREATMENT A. Short-Term Wind Protection Joint Treatment (Uncontrolled Enclosure): 1. Panel Joint and Penetration Treatment: Promptly after sheathing is installed, apply acrylic-coated polypropylene sheathing tape to panel joints and a. Center tape over sheathing panel joints and on perimeter openings surrounding b. Tape seams in continuous lengths as long as possible, with firm and continuous adhesion. c. Provide an overlap at intersections at least equal to the tape width. 2. Fastener Treatment: None. B. Short-Term Wind and Rain Protection Joint Treatment (Uncontrolled Enclosure): 1. Panel Joint and Penetration Treatment: a. Apply at least a 3/8-inch continuous bead of sealant over the sheathing panel joint. Provide a backer rod for joint openings wider than 1/8-inch. b. With a trowel, compress the sealant into the joints creating a continuous, flat, and level surface. 2. Fastener Treatment: None. C. Long-Term Wind and Water Protection Joint Treatment (Partially-Controlled Enclosure): 1. Panel Joint and Penetration Treatment: Promptly after sheathing is installed, apply glass mesh joint tape to panel joints and penetrating items promptly after sheathing is installed. a. Center tape over sheathing panel joints and on perimeter openings surrounding b. Provide an overlap at intersections at least equal to the tape width. c. Apply at least a 3/8-inch continuous bead of sealant over the glass mesh joint tape, centered over sheathing panel joints and on perimeter openings surrounding d. With a trowel, compress and embed the sealant into the entire surface of the tape creating a continuous, flat, and level surface. 2. Alternate Panel Joint and Penetration Treatment: As an alternate to sealant and glass mesh tape, specified seam seal tape may be provided when applied to properly prepared and primed sheathing surfaces in conformance with the seam seal tape manufacturer s published installation instructions. 3. Fastener Treatment: Apply sealant to each exposed fastener; trowel level and smooth. GYPSUM SHEATHING

4 PART 3 - EXECUTION 3.1 INSTALLATION REQUIREMENTS A. General: 1. Install gypsum sheathing in compliance with ASTM C 1280, GA publication GA-253, Application of Gypsum Sheathing, and the following. a. Comply with the manufacturer s installation instructions when installing protecting, and repairing sheathing and accessories. b. Use materials and methods required, recommended, approved, or accepted by the manufacturer, along with manufacturer-recommended accessories and techniques. c. In the event of conflict between the manufacturer s instructions and the referenced standards, then the manufacturer s instructions govern. 2. Do not install materials with defects that impair the quality of sheathing, or pieces that are too small to use with at least a number of joints or optimum joint arrangement. Use appropriate-length materials to minimize end joints. B. Special Techniques: 1. Furnish units in longest available lengths to minimize end joints. 2. Pre-cut panels and make accurate cutouts for penetrations. 3. Position gypsum sheathing next to framing with coated (gray) side away from studs. a. Fit ends closely. b. Cut panel to required size and make cutouts. c. Leave 1/8-inch gap between penetrating items and panel edges. 4. Orient panels with long edge perpendicular to framing and short edges vertically oriented and centered over studs. a. Fit sheathing snugly around openings. b. Install panels with at least a 3/8-inch gap where non-load-bearing construction abuts structural elements. c. Install panels with at least a 1/4-inch gap where they abut masonry or similar materials that may retain moisture. d. Do not bridge building expansion or seismic joints. Cut and space edges of panels to match framing spacing. 5. Securely fasten sheathing panels to framing. a. Stagger vertical joints at least 16 inches on center, but not less than one framing space between adjacent rows. b. Locate fasteners at least 3/8-inch from perimeter edges, and space fasteners a maximum of 8 inches on center, both along the panel perimeter and over the panel face. c. Drive fasteners to bear tightly against sheathing faces. Do not break or rupture facing, fracture underlying core or countersink fasteners. GYPSUM SHEATHING

5 3.2 PANEL JOINT AND PENETRATION TREATMENT A. Long-Term Joint Treatment: 1. Promptly after sheathing is installed, apply glass mesh joint tape centered over sheathing panel joints and around Provide minimum overlap at intersections greater than or equal to tape width. 2. Apply at least a 3/8-inch continuous bead of sealant over the glass mesh joint tape, centered over sheathing panel joints and on perimeter openings surrounding 3. With a trowel, compress and embed the sealant into the entire surface of the tape creating a flat and level surface. 4. As an alternate to sealant and glass mesh tape, specified seam seal tape may be provided when applied to properly prepared and primed sheathing surfaces in compliance with the seam seal tape manufacturer s published installation instructions. B. Fastener Treatment: Apply sealant to each exposed fastener; trowel level and smooth. END OF SECTION GYPSUM SHEATHING