Section III – Single Ply Application

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III. SINGLE-PLY APPLICATION

The finished quality of single-ply surfaces depends on accurately installed and aligned framing. So, before initiating a single-ply application of gypsum board, check the framing or furring members for firmness and alignment (Fig. 11). Gypsum board is generally attached to framing with nails, screws, or staples. Staples are economical and can be quickly applied with staple guns; however, their application is limited to the base-ply of two layers or for gypsum sheathing over wood framing.

 

Nail Attachment and Spacing

Gypsum board can be nail-attached using either a single-nailing or double-nailing pattern. Double-nailing produces a tighter board-to-stud contact. Applicators must follow the nail spacing specified in the fire test to meet fire resistive construction requirements.

Space single nails a maximum of 7 inches o.c. on ceilings and 8 inches o.c. on walls along framing supports (Fig. 24)1. First drive nails in the center or field of the board and then outward toward the edges and ends. In single-ply installation, place all ends and edges of gypsum boards over framing members or other solid backing except where treated joints are at right angles to framing members.

1For fire- and sound-rated construction, framing and fastener size and spacing must follow that of the system tested. Refer to Gypsum Association GA-600, Fire Resistance Design Manual, for

details of fire resistive construction.

When double-nailing, space the first set of nails 12 inch o.c. and the second nailing 2 inch to 2-1/2 inch from the first (Fig. 25). Apply the second set of nails in the same sequences as the first set, but not along the perimeter of the board. Reseat the first nails driven as necessary following application of the second set.

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Attachment Procedures

1. Carefully measure and cut the board.

2. Prior to nailing, mark the gypsum board to indicate the location of the framing.

3. Hold board firmly against framing when nailing to avoid nail pops or protrusions.

4. Drive nails straight into the framing member. Remove nails that miss the supports, dimple the nail holes, and then cover with joint compound.

5. Correct damage to the board caused by over driving nails by driving a new nail 2 inch away from the damaged site to provide firm attachment. Repair damaged area with joint compound.

See figures 26 and 27 for examples of correctly and incorrectly driven nails. Other common causes of face paper fractures are misaligned or twisted supporting framing members (Fig. 11) and projections of improperly installed blocking or bracing. These framing faults prevent solid contact between gypsum board and supporting members, and hammer impact causes the board to rebound and rupture the paper. Correct defective framing prior to application of gypsum board. Trim or reinstall protruding supporting members. Minimize problems resulting from such defects by using screws, adhesives or two-ply construction.

 

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Figure 27

Fig. 24 – Single Nailing Pattern

Figure 28

Fig.25 – Double Nailing Pattern

Figure 29

Fig. 26 – Cross-Section of Examples of Mis-driven Nails

Fig. 27 – Cross-Section of Properly Driven Nail

Screw Attachment

Screw attachment of gypsum board requires the least number of fasteners. Using screws minimizes the number of fastener heads requiring treatment with joint compound and reduces the number of possible application defects. Do not exceed 12 inches o.c. between screws on ceilings and 16 inches o.c. on walls where framing members are 16 inch o.c. Do not exceed 12 inch o.c. between screws on walls and ceilings where framing members are 24 inch o.c. See Figure 21 for the necessary penetration for screws.

Use Type S screws to attach gypsum board to metal framing and furring. Do not exceed more than 12 inch o.c. between screws along supports for both walls and ceilings. These screw spacings are also appropriate for gypsum board mounted on resilient furring channels over wood framing.

Note: One may use a combination of fasteners consisting of nails along the perimeter and screws in the field of the gypsum board. Do not allow the spacing between a nail and an adjacent screw to exceed the spacing specified for screws.

 

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Floating Interior Angle Construction

The floating interior angle method helps minimize the possibility of fastener popping in areas adjacent to the wall and ceiling intersection and to minimize cracking due to structural stresses. This method is suited to either single or double layer application of gypsum board to wood framing.Use the floating interior angle method is applicable for single nailing, double nailing or screw attachment. Maintain the same nail-free clearances at corners as in double nailing. See Figure 28 .

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Figure 31

Fig. 28 – Floating Angle Construction

In floating interior angle construction where the ceiling framing members are perpendicular to the wall/ceiling intersection, locate the ceiling fasteners 7 inches from the intersection for single nailing and 11 to 12 inch for double nailing or screw application. On ceilings, where the joists are parallel to the intersection with a wall, start nailing at the intersection. Apply gypsum board first to ceilings and then to walls.

Apply gypsum board to sidewalls in such a manner as to provide a firm, level support for the floating edges of the ceiling board. Locate the top attachment into each stud 8 inches down from the ceiling intersection for single nailing, and 11 to 12 inches for double nailing or screw applications (Figs. 29a and 29b). At vertical angles, (Fig. 29c) apply the overlapping board firmly against the underlying board to bring the underlying board into firm contact with the face of the framing member behind it. Attach the overlapping board with nails or screws and omit fasteners from the underlying board at the vertical intersection.

 

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Figure 32a

Fig. 29a – Vertical Section, Ceiling Framing Member Perpendicular to Wall

Figure 32b

Fig. 29b –Vertical Section, Ceiling Framing Parallel to Wall

Figure 32c

Fig. 29c – Cross Section Through Interior Vertical Angle

Special clips designed to support gypsum wallboard at wall corners and wall/ceiling intersections may be used where approved. These clips are used to replace one of the two conventional “back up” studs or blocking used to provide support at such locations. Clip spacing varies according to the type of clips; see clip manufacturer’s recommendations (Figs. 30a, 30b, 30c )

 

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Figure 33a

Fig. 30a – Special Clips Used When Joists Are Parallel to Intersection of Wall

Figure 33b

Fig. 30b – Special Clips at Interior Corners Eliminate Backup Stud

Figure 33c

Fig. 30c – Special Clips Allow Corners to Be Fully Insulated

Joint Location at Openings

The layout of gypsum board joints needs to be planned around openings such as doors and windows to reduce the possibility of unsightly cracking as the building settles after construction. The ends of edges of gypsum board applied in either the horizontal or vertical direction should not be placed at the edge of a door or window opening, unless a control joint is to be installed at that location.

 

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Air Barrier Installation

Apply a bead of caulk to bottom and top edges to prevent unwanted passage of air.

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