Figure 5-9.Finishing drywall joints.
Applying drywall in older buildings yields a lot of
waste because framing is not always standardized. Use
the cutoffs in such out-of-the-way places as closets.
Dont piece together small sections in areas where youll
notice seams. Never assume that ceilings are square with
walls. Always measure from at least two points, and cut
Drywall is quite good for creating or covering
curved walls. For the best results, use two layers or
1/4-inch drywall, hung horizontally. The framing
members of the curve should be placed at intervals of
no more than 16 inches OC; 12 inches is better. For an
8-foot sheet applied horizontally, an arc depth of 2 to 3
feet should be no problem, but do check the
manufacturers specifications. Sharper curves may
require backcutting (scoring slots into the back so that
the sheet can be bent easily) or wetting (wet-sponging
the front and back of the sheet to soften the gypsum).
Results are not always predictable, though. When
applying the second layer of 1/4-inch drywall, stagger
the vertical butt joints.
The finishing of gypsum board drywall is generally
a three-coat application. Attention to drying times
between coats prevents rework that has a cost involved
as well as extra time.
Where sheets of drywall join, the joints are covered
with joint tape and compound (fig. 5-9). The procedure
Spread a swath of bedding compound about 4
inches wide down the center of the joint (fig. 5-9,
view A). Press the tape into the center of the joint
with a 6-inch finish knife (fig. 5-9, view B).
Apply another coat of compound over the first
to bury the tape (fig. 5-9, view C). As you apply
the compound over the tape, bear down so you
take up any excess. Scrape clean any excess,
however, as sanding it off can be tedious.
When the first coat is dry, sand the edges with
fine-grit sand paper while wearing personal-
protective equipment. Using a 12-inch knife,
apply a topping of compound 2 to 4 inches wider
than the first applications (view D).
Sand the second coat of compound when it is
dry. Apply the third and final coat, feathering it
out another 2 to 3 inches on each side of the joint.
You should be able to do this with a 12-inch
knife, Otherwise, you should use a 16-inch