SECTION 09253

GYPSUM SHEATHING

Verify that Section titles referenced in this Section are correct for this Project's Specifications; Section titles may have changed.

PART 1 - GENERAL

1.1RELATED DOCUMENTS

  1. Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division1 Specification Sections, apply to this Section.

1.2SUMMARY

  1. This Section includes the following:
  2. Glass-mat gypsum sheathing board.

If retaining second option in subparagraph below, verify requirements of authorities having jurisdiction.

  1. Sheathing joint-and-penetration treatment.
  1. Related Sections include the following:
  2. Section 07620 - Sheet Metal Flashing and Trim
  3. Section 09260 - Gypsum Board Assemblies

1.3DEFINITIONS

  1. Gypsum Board Construction Terminology Standard: Refer to ASTMC11 for definitions of terms for gypsum sheathing board construction not defined in this Section or in other referenced standards.

1.4SUBMITTALS

  1. Product Data: For each type of product indicated.

Retain below if applicable.

  1. Building Wrap: For air/moisture-infiltration protection, include data substantiating compliance with building code in effect for Project.

1.5QUALITY ASSURANCE

Retain this Article for fire-rated assemblies.

  1. Fire-Test-Response Characteristics: For assembles with fire-resistance ratings, provide materials and construction identical to those of assemblies tested for fire resistance per ASTME119 by a testing and inspecting agency acceptable to authorities having jurisdiction.

Indicate design designations of specific assemblies on Drawings.

  1. Fire-Resistance Ratings: Indicated by design designations from UL's "Fire Resistance Directory." GA-600, "Fire Resistance Design Manual."

1.6DELIVERY, STORAGE, AND HANDLING

  1. Store materials protected against damage from weather, direct sunlight, surface contamination, corrosion, construction traffic, or other causes. Stack sheathing flat on leveled supports off the ground, under cover, and fully protected from weather.

1.7COORDINATION

Coordinate this Article with Sections in which exterior cladding is specified.

Retain paragraph and subparagraph below for G-P Gypsum Corporation's "Dens-Glass Gold."

  1. Glass-Mat Gypsum Sheathing Board:
  2. Do not leave exposed to weather for more than 180 days.

PART 2 - PRODUCTS

2.1GYPSUM SHEATHING

Only G-P Gypsum produces a glass-mat gypsum sheathing board.

  1. Glass-Mat Gypsum Sheathing Board: ASTMC1177/C1177M.
  2. Product: Subject to compliance with requirements, provide "Dens-Glass Gold" by G-P Gypsum Corporation.
  3. Type and Thickness: TypeX, 5/8 inch (15.9 mm) thick. 48 by 96 inches (1219 by 2438 mm), 48 by 108 inches (1219 by 2743 mm), 48 by 120 inches (1219 by 3048 mm).

2.2WEATHER-RESISTANT BARRIER

Retain this Article for applications where a weather-resistant barrier is required, such as behind siding or brick veneer. Delete if a weather-resistant barrier is not required for protection during construction period or if sheathing forms substrate for exterior insulation and finish systems or similar construction. See "Air/Moisture-Infiltration Protection" Article in the Evaluations.

  1. Building Paper: ASTMD226, Type1 (No.15 asphalt-saturated organic felt), unperforated.

Retain paragraph above or paragraph and applicable subparagraphs below.

  1. Building Wrap: ASTME1677, TypeI air retarder; with flame-spread and smoke-developed indexes of less than 25 and 450, respectively, when tested according to ASTME84; and UV stabilized.

Coordinate permeance value retained or inserted in subparagraph below with products selected. Consult manufacturers' literature.

  1. Permeance: Not less than 152 g through 1 sq. m of surface in 24 hours per ASTME96, Desiccant Method (ProcedureA).

Coordinate material retained or inserted in subparagraph below with products selected. See "Air/Moisture-Infiltration Protection" Article in the Evaluations and consult manufacturers' literature.

  1. Material: Manufacturer's standard.

2.3SHEATHING JOINT-AND-PENETRATION TREATMENT MATERIALS

If desired and a weather-resistant barrier is not required by authorities having jurisdiction, retain this Article.

  1. Glass-Mat Gypsum Sheathing Board:
  2. Silicone Emulsion Sealant: ASTMC834, compatible with sheathing tape and sheathing, recommended by tape and sheathing manufacturers for use with glass-fiber sheathing tape and for covering exposed fasteners.
  3. Glass-Fiber Sheathing Tape: Self-adhering glass-fiber tape, minimum 2 inches (50 mm) wide, 10 by 10 or 10 by 20 threads/inch (390 by 390 or 390 by 780 threads/m), of type recommended by sheathing and tape manufacturers for use with silicone emulsion sealant in sealing joints in glass-mat gypsum sheathing board and with a history of successful in-service use.

2.4ACCESSORY MATERIALS

Revise paragraph below if stainless-steel drill screws are required or delete paragraph and insert fastener requirements for attaching sheathing to wood framing.

  1. Fasteners: Steel drill screws, in length recommended by sheathing manufacturer for thickness of sheathing board to be attached, with organic-polymer or other corrosion-protective coating having a salt-spray resistance of more than 800 hours according to ASTMB117.
  2. For steel framing less than 0.0329 inch (0.835 mm) thick, attach sheathing with steel drill screws complying with ASTMC1002.

PART 3 - EXECUTION

3.1GYPSUM SHEATHING INSTALLATION

  1. Comply with GA-253 and manufacturer's written instructions.
  2. Cut boards at penetrations, edges, and other obstructions of work; fit tightly against abutting construction, unless otherwise indicated.

Retain applicable subparagraph(s) below or insert requirements to suit Project.

  1. Install boards with a 3/8-inch (9-mm) setback where non-load-bearing construction abuts structural elements.
  2. Install boards with a 1/4-inch (6.4-mm) setback where they abut masonry or similar materials that might retain moisture, to prevent wicking.
  1. Coordinate sheathing installation with flashing and joint-sealant installation so these materials are installed in sequence and manner that prevent exterior moisture from passing through completed exterior wall assembly.
  2. Apply fasteners so screw heads bear tightly against face of sheathing boards but do not cut into facing.
  3. Do not bridge building expansion joints with sheathing; cut and space edges to match spacing of structural support elements.
  4. Vertical Installation: Install board vertical edges centered over flanges of steel studs. Abut ends and edges of each board with those of adjacent boards. Screw-attach boards at perimeter and within field of board to each steel stud.
  5. Space fasteners approximately 8 inches (200 mm) o.c. and set back a minimum of 3/8 inch (9 mm) from edges and ends of boards.

Retain subparagraph above or below. Delete below if not applicable or not permitted.

  1. For sheathing under stucco cladding, boards may be initially tacked in place with screws if overlying self-furring metal lath is screw-attached through sheathing to studs immediately after sheathing is installed.

3.2SHEATHING JOINT-AND-PENETRATION TREATMENT

Retain this Article if joints are sealed in lieu of using a weather-resistant barrier; verify requirements of authorities having jurisdiction.

  1. Seal sheathing joints according to sheathing manufacturer's written recommendations.
  2. Apply glass-fiber sheathing tape to glass-mat gypsum sheathing board joints, and apply and trowel silicone emulsion sealant to embed sealant in entire face of tape. Apply sealant to exposed fasteners with a trowel so fasteners are completely covered. Seal other penetrations and openings.

END OF SECTION

09253 - 1LK 00000