Veneer plaster provides a hard, smooth finish for walls and
Skim-coat plastering has replaced traditional plastering in
the construction of most residential interior walls and
ceilings. It's also making inroads among builders making the
switch from tape-and-finish drywall. If you're unfamiliar with
skim-coat plastering, also called veneer plastering, you're not
alone. I work in southeastern Connecticut, where plastering is
seldom seen in new construction. Yet just 20 miles east, in
Rhode Island, skim-coat plaster is common.
Skim-coat is a thin layer of plaster applied over a special
gypsum panel called blueboard. The paper facing is chemically
treated to provide a bonding surface for plaster, and the blue
color distinguishes it from regular gypsum board. After the
board is hung, the entire surface is covered with an even coat
of plaster, which is smoothed and polished. This process is
significantly less expensive than wire lath plastering, but at
an average cost of $1.10 to $1.30 per square foot, it's
somewhat more expensive than joint-compound taping.
Advantages of Skim-Coat
In my opinion, skim-coat plaster resolves the shortcomings of
drywall. Veneer plaster is monolithic, so there's no "tell"
from the seams. Low-angle sunlight reveals all of the
imperfections of drywall, but plaster has a smooth texture that
looks good in any light. Besides, unless joint compound is
skim-coated over the entire surface, the differences in texture
between the paper and the joint compound tend to "read" through
a gloss paint finish. One coat of plaster veneer can double or
triple the 1,000-psi compressive strength of a 1/2-inch gypsum
panel. A two-coat plaster system can increase the strength to
over 4,000 psi, making dents and nail pops highly unlikely.
Veneer plastering can be completed faster than drywall. An
experienced plasterer can skim about 750 square feet of surface
per day, and a typical crew can plaster a 2,000-square-foot
house in two days. There is zero sanding, and the finished
product can be painted as soon as 24 hours after the plaster
application, depending on the room's temperature and
Plaster is more fire-retardant than exposed paper, and its
denser surface is better at minimizing sound transmission. For
these reasons, not to mention the dust-free application, my
customers are willing to pay the moderately higher cost for
1. The most commonly used veneer plasters in
southern New England are USG's Diamond and Imperial,
and Gold Bond's Uni-Kal. Base-coat plaster is used in
two-coat veneer systems. Imperial contains a fine
aggregate that increases its compressive strength, but
makes it more difficult to work with.
We commonly use three kinds of veneer plaster in southern New
England: United States Gypsum's (USG) Imperial, USG's Diamond,
and Gold Bond's Uni-Kal (see Figure 1). The choice depends on
the plasterer's preference and what the job calls for. For most
jobs, I prefer to use Diamond plaster. I find Imperial to be
the most difficult to work with and the hardest to get smooth,
but it produces a very abrasion-resistant finish, with a
reported 3,000-psi compressive strength.
Tools of the trade. I have invested thousands
of dollars in tools for my remodeling business. But the tool I
take the best care of is my $21, 13-inch Marshalltown
stainless-steel plastering trowel. It's the one tool I never
leave overnight at a job site, because a nick on any edge will
render it useless. After three years of heavy use, it's broken
in real nice and is my most valuable plastering tool.
Most plastering trowels are 5 inches wide and vary in
length. In theory, I could be more productive with a 16-inch
trowel, because it covers more surface per sweep, but I'm more
comfortable with the 13-inch. I also have a 4x11-inch trowel
for tight spaces. The edge of a trowel gets better over time as
it tapers and thins from wear. A corner trowel, also called a
butterfly, is used to make crisp 90-degree inside corners.
2. Tools of the plastering trade include a hawk
and assorted trowels, a felt blister brush,
miscellaneous paint brushes, and a spray bottle. A cage
mixer (right) chucked in a low-speed drill ensures a
smooth batch of plaster.
Besides a few good trowels, you also need hawks, stilts,
staging, mixing containers, scoops, and a mixing table (Figure
2). The mixing table is a waist-high surface used to hand-mix
traditional plasters. But since veneer plaster is machine-mixed
in a container, the table is used solely to hold the batch for
easy hawk loading. I find that a non-absorbent plastic laminate
surface works well.