To prevent damage from structural movements or dimensional changes, control and expansion joints should be provided and floating-angle construction used, as described in Art. 11.27.
Many building components may be affected by the decision to use gypsumboard construction. For example, window and door frames should have the appropriate depth for the wall thickness resulting from use of wallboard. Therefore, walls and partitions and related installations, including mechanical and electrical equipment, should be carefully planned and coordinated.
Application. Wallboard preferably should be applied to studs with long dimension horizontal (Fig. 11.23), and vertical joints should be staggered. In ceilings, the long sides should span supports (often referred to as horizontal, or across, application).
Board ends and edges parallel to framing or furring should be supported on those members, except for face layers of two-ply systems. Otherwise, back blocking should be used to reinforce the joints.
Ceiling panels should be installed first, then the walls. Adjoining boards should be placed in contact, but not forced against each other. Tapered edges should be placed next to tapered edges, square ends in contact with square ends. (Joints formed by placing square ends next to tapered edges are difficult to conceal.)
Furring. Supplementary framing, or furring, should be used when framing spacing exceeds the maximum spacing recommended by the gypsumboard manufacturer for the thickness of board to be used (Table 11.10), or when the surface of framing or base layer is too far out of alignment.
At gypsumboard joints, wood furring should be at least 11â„2 in wide, and metal furring 11â„4 in wide, to provide adequate bearing surface and space for attachment of the gypsumboard. The furring should be aligned to receive the board, and securely fastened to framing or masonry or concrete backing. For rigidity, lumber used for furring should be at least 2 x 2 in when nails are used and 1 x 3 in when screws are used for attachment of gypsumboard. Furring on masonry or concrete may be as small as 5â„8 x 11â„2 in.
Fastening. Gypsumboards may be held in place with various types of fasteners or adhesives, or both. Special nails, staples, and screws are required for attachment of gypsumboards, because ordinary fasteners may not hold the boards tightly in place or countersink neatly, to be easily concealed. Clips and staples may be used only to attach the base layer in multi-ply construction.
