Building Design and Construction Handbook - Merritt - Ventech!

WALL, FLOOR, AND CEILING SYSTEMS 11.65
Adhesives. These may be used to attach gypsumboard to framing or furring, or
to existing flat surfaces. Nails or screws may also be used to provide supplemental
support.
Adhesives used for bonding wallboard may be classified as stud, laminating, or
contact or modified contact.
Stud adhesives are used to attach wallboard to wood or steel framing or furring.
They should conform with ASTM C557. They should be applied to supporting
members in continuous, or nearly so, beads.
Laminating adhesives are used to bond gypsumboards to each other, or to
suitable masonry or concrete surfaces. They are generally supplied in powder form,
and water is added on the site. Only as much adhesive should be mixed at one time
as can be applied within the period specified by the manufacturer. The adhesive
may be spread over the entire area to be bonded, or in parallel beads or a pattern
of large spots, as recommended by the manufacturer. Supplemental fasteners or
temporary support should be provided the face boards until sufficient bond has been
developed.
Contact adhesives are used to laminate gypsumboards to each other, or to attach
wallboard to metal framing or furring. A thin, uniform coat of adhesive should be
applied to both surfaces to be joined. After a short drying time, the face board
should be applied to the base layer and tapped with a rubber mallet, to ensure
overall adhesion. Once contact has been made, it may not be feasible to move or
adjust the boards being bonded.
Modified contact adhesives, however, permit adjustments, often for periods of
up to 1 ⁄2 hr after contact. Also, they generally are formulated with greater bridging
ability than contact adhesives. Modified adhesives may be used for bonding wallboard
to all kinds of supporting construction.
See also Arts. 11.26.2 to 11.26.4 and 11.27.
11.26.2 Single-Ply Gypsumboard Construction
A single-ply system consists of one layer of wallboard attached to framing, furring,
masonry, or concrete (Fig. 11.23). This type of system is usually used for residential
construction and where fire-rating and sound-control requirements are not stringent.
Maximum spacing of supports should not exceed the limits specified in Table 11.10.
Nail Attachment. Spacing of nails generally is determined by requirements for
fire resistance and for firmness of contact between wallboard and framing necessary
to avoid surface defects. Spacing normally used depends on whether single nailing
or double nailing is selected. Double nailing provides tighter contact, but requires
more nails. In either method, one row of nails is driven along each support crossed
by a board or on which a board end or edge rests. The spacing applies to the centerto-center
distance between nails in each row.
In the single-nailing method, nails should be spaced not more than 7 in apart
for ceilings and 8 in apart for walls (Fig. 11.25).
In the double-nailing method, pairs of nails are driven 12 in c to c, except at
edges or ends, in a special sequence (Fig. 11.26). First, one nail of each pair is
placed, starting at the middle of the board and then proceeding toward edges and
ends. Next, the second nail is driven 2 in from the first. Finally, the first set of nails
placed should be given an extra hammer blow to reseat them firmly. Single-nailing
spacing should be used for edges or ends at supports.