Finishes 201The spacing of fasteners must also be determined either
from the specifications or, if it is not given there, from the
manufacturer’s recommendations. The estimator should
make a list of accessories, the materials from which they are
fabricated, and the finish required.
Estimating. All wallboard should be taken off by the
square foot, with the estimator double-checking for panel
layout of the job. The first step is to determine the linear
footage of each type of wall, carefully separating any wall
with different sizes or types of material, fasteners, or any
other variations. There are two sides to most walls, and each
side requires a finish. After a complete listing has been made,
the square footage of wallboard may be determined.
Different varieties may be encountered, and each must be
kept separate.
Equipment required may simply be wood or metal
horses, planks, platforms, and scaffolding as well as small
electric tools and staplers. On projects with high ceilings,
scaffolds on wheels are often used so that the workers can
work more conveniently, and the scaffold may be moved eas-
ily from place to place.
Labor for drywall construction will vary depending on
the type of wallboard trim, fasteners, whether the walls are
straight or jogged, height of walls or ceiling, and the presence
of other construction underway at the time. Many subcon-
tractors are available with skilled workers specially trained for
this type of work.
16–6 Drywall Partitions
Drywall partitions consist of wallboard over supporting
construction; backing board may also be required. The
types of materials used for this construction will depend
on the requirements of the job with regard to appearance,
sound control, fire ratings, strength requirements, and
cost. Materials may be easily interchanged to meet all
requirements.
Each component of the drywall construction assembly
must be taken off and estimated separately. Plain gypsum
wallboard will require a finish of some type, such as painting
or wallpaper.
Gypsum wallboard with a rugged vinyl film that is fac-
tory laminated to the panel is also available. The vinyl-finished
panel is generally fastened with adhesives or clips and match-
ing vinyl-covered trim; it is also available in fire-resistant
gypsum wallboard where fire-rated construction is desired or
required.
Fire-resistant gypsum wallboard is available generally in
1/2- and 5/8-inch thicknesses. These panels have cores, con-
taining special mineral materials, and can be used in assem-
blies that provide up to two-hour fire ratings in walls and
three-hour fire ratings in ceilings and columns.
Other commonly used gypsum wallboards include insu-
lating panels (aluminum foil on the back), water-resistant
panels (for use in damp areas; they have special paper and core
materials), and backing board, which may be used as a base
for multi-ply construction and acoustical tile application, and
which may be specially formulated for a fire-resistant base for
acoustical tile application.
The supporting construction for ceilings generally uti-
lizes wood joists and trusses, steel joists and suspended ceil-
ings, and concrete and masonry, sometimes in conjunction
with the various types of furring materials available.
Drywall construction is generally estimated by the
square foot, square yard, and square, each estimator using
whichever seems most comfortable. The most common
approach to estimating drywall partitions is to take the lin-
ear footage of each different type and thickness of the wall
from the plan and list them on the workup sheet. Walls that
are exactly the same should be grouped together; any varia-
tion in the construction of the wall will require that it be
considered separately. If the ceiling heights vary throughout
the project, the lengths of walls of each height must also be
kept separately.
Once the estimator makes a listing of wall lengths and
heights, multiply the length times height and determine the
square footage of the partition. With this information, the
amounts of material required may be estimated. Deduct all
openings from the square footage, and add 8 to 10 percent
for waste.16–7 Column Fireproofing
Columns may be fireproofed by using drywall construction
consisting of layers of fire-resistant gypsum wallboards held
in place by a combination of wire, steel studs, screws, and
metal angles. Up to a three-hour fire rating may be obtained
by using gypsum board. A four-hour fire rating is available
when the gypsum board is used in conjunction with gypsum
tile (usually 2 or 3 inches thick). To receive the fire ratings, all
materials must be installed in accordance with U.L. designs.
A complete takeoff of materials is required. No adhesives
may be used.16–8 Accessories
Accessories for the application and installation of drywall
construction include mechanical fasteners and adhesives,
tape and compound for joints, fastener treatment, trim to
protect exposed edges and exterior corners, and base plates
and edge moldings.Mechanical Fasteners. Clips and staples may be used
to attach the base ply in multi-ply construction. The clip
spacing may vary from 16 to 24 inches on center and may
also vary depending on the support spacing. Staples should
be 16-gauge galvanized wire with a minimum of a 7/16-
inch-wide crown with legs having divergent points. Staples
should be selected to provide a minimum of 5/8-inch pen-
etration into the supporting structure. They are spaced
about 7 inches on center for ceilings and 8 inches on center
for walls.