GYPSUM BOARD MATERIALS AND ACCESSORIES
|Accessories for gypsum board||ASTM C1047|
|Adhesives for fastening gypsum wallboard||ASTM C557|
|Elastomeric joint sealants||ASTM C920|
|Fiber-reinforced gypsum panels||ASTM C1278|
|Glass mat gypsum backing panel||ASTM C1178|
|Glass mat gypsum panel||ASTM C1658|
|Glass mat gypsum substrate||ASTM C1177|
|Joint reinforcing tape and compound||ASTM C474; C475|
|Nails FOR gypsum boards||ASTM C514, F547, F1667|
|Steel screws||ASTM C954; C1002|
|Steel studs, load-bearing||ASTM C 955|
|Steel studs, nonload-bearing||ASTM C 645|
|Standard specification for gypsum board||ASTM C1396|
|Testing gypsum and gypsum products||ASTM C22; C472; C473|
LATH, PLASTERING MATERIALS AND ACCESSORIES
|Accessories for gypsum veneer base||ASTM C1047|
|Blended cement||ASTM C595|
|Exterior plaster bonding compounds||ASTM C932|
|Gypsum casting and molding plaster||ASTM C59|
|Gypsum Keene's cement||ASTM C61|
|Gypsum plaster||ASTM C28|
|Gypsum veneer plaster||ASTM C587|
|Interior bonding compounds, gypsum||ASTM C631|
|Lime plasters||ASTM C5; C206|
|Masonry cement||ASTM C91|
|Metal lath||ASTM C847|
ASTM C35; C 897ASTM C35
|Plastic cement||ASTM C1328|
|Portland cement||ASTM C150|
|Steel screws||ASTM C1002; C954|
|Steel studs and track||ASTM C 645; C 955|
|Welded wire lath||ASTM C933|
|Woven wire plaster base||ASTM C1032|
Gypsum board and gypsum plaster construction shall be of the materials listed in Tables 2506.2 and 2507.2. These materials shall be assembled and installed in compliance with the appropriate standards listed in Tables 2508.1 and 2511.1.1, and Chapter 35.
Exception: Joint and fastener treatment need not be provided where any of the following conditions occur:
- Where the gypsum board is to receive a decorative finish such as wood paneling, battens, acoustical finishes or any similar application that would be equivalent to joint treatment.
- On single-layer systems where joints occur over wood framing members.
- Square edge or tongue-and-groove edge gypsum board (V-edge), gypsum backing board or gypsum sheathing.
- On multilayer systems where the joints of adjacent layers are offset from one to another.
- Assemblies tested without joint treatment.
|MATERIAL||THICKNESS OF MATERIAL |
|SPACING OF FRAMING |
|SHEAR VALUEa, b |
(plf of ceiling)
|MIMIMUM FASTENER SIZE|
|Gypsum board||1/2||16 o.c.||90||5d cooler or wallboard nail; |
15/8-inch long; 0.086-inch shank;15/64-inch headc
|Gypsum board||1/2||24 o.c.||70||5d cooler or wallboard nail; |
15/8-inch long; 0.086-inch shank;15/64-inch headc
For SI: 1 inch = 25.4 mm, 1 pound per foot = 14.59 N/m.
- Values are not cumulative with other horizontal diaphragm values and are for short-term loading due to wind or seismic loading. Values shall be reduced 25 percent for normal loading.
- Values shall be reduced 50 percent in Seismic Design Categories D, E and F.
- 11/4-inch, No. 6 Type S or W screws are permitted to be substituted for the listed nails.
Water-resistant gypsum backing board shall not be used in the following locations:
- Over a vapor retarder in shower or bathtub compartments.
- Where there will be direct exposure to water or in areas subject to continuous high humidity.
- On ceilings where frame spacing exceeds 12 inches (305 mm) o.c. for 1/2-inch thick (12.7 mm) water-resistant gypsum backing board and more than 16 inches (406 mm) o.c. for 5/8-inch thick (15.9 mm) water-resistant gypsum backing board.
Water-resistive barriers shall be installed as required in Section 1404.2 and, where applied over wood-based sheathing, shall include a water-resistive vapor-permeable barrier with a performance at least equivalent to two layers of Grade D paper. The individual layers shall be installed independently such that each layer provides a separate continuous plane and any flashing (installed in accordance with Section 1405.4) intended to drain to the water-resistive barrier is directed between the layers.
Exception: Where the water-resistive barrier that is applied over wood-based sheathing has a water resistance equal to or greater than that of 60-minute Grade D paper and is separated from the stucco by an intervening, substantially nonwater-absorbing layer or drainage space.
Plastering gypsum plaster or cement plaster shall not be less than three coats where applied over metal lath or wire fabric lath and not less than two coats where applied over other bases permitted by this chapter.
Installation of lathing and plaster materials shall conform with Table 2511.1.1 and Section 2507.
First and second coats of cement plaster shall be applied and moist cured as set forth in ASTM C 926 and Table 2512.6.
|COAT||MINIMUM PERIOD |
|MINIMUM INTERVAL |
|First||48 hoursa||48 hoursb|
|Second||48 hours||7 daysc|
- The first two coats shall be as required for the first coats of exterior plaster, except that the moist-curing time period between the first and second coats shall not be less than 24 hours. Moist curing shall not be required where job and weather conditions are favorable to the retention of moisture in the cement plaster for the required time period.
- Twenty-four-hour minimum interval between coats of interior cement plaster. For alternative method of application, see Section 2512.8.
- Finish coat plaster is permitted to be applied to interior cement plaster base coats after a 48-hour period.