Making Old Stucco Look New, continued
The foam adheres surprisingly well. I was once installing a
long run of trim and someone bumped the transit while I was
eating lunch. We set the trim to what we thought was a level
line, and it wasn't until the next day that we noticed it was
off. The trim was harder to remove than you might imagine. We
had to saw it off and use a grinder to remove the glue and
remaining bits of foam.
We usually apply foam, then allow the adhesive to cure
overnight. The trim will come off the wall while the Foam Tite
is wet, but it's rock-solid once the adhesive cures.
The next day, we apply fiberglass mesh tape to the trim. The
mesh reinforces the surface and holds everything together.
Precoated trim is already covered with mesh, so we have to tape
only the joints. With raw foam, we cover the entire piece and
span the joints (Figure 6).
Figure 6. Joints between
pieces of trim are reinforced with fiberglass mesh (left). A
layer of Foam Tite is then applied over the mesh to fill voids
and bond the pieces together (right).
If there's a big gap between the trim and the wall, we'll tape
that joint too. After the mesh is in place, we go over it with
a layer of Foam Tite. This fills in the weave and bonds the
mesh to the trim. Once the adhesive sets, the wall and the
individual pieces of trim are effectively a single unit (Figure
7. This sill and casing (left) have been glued
to the wall and joined with mesh and Foam Tite. On this
house, the trim will be the same color as the wall
(below), but it could just as easily receive a
Prepping the Walls
It goes without saying that the wall surfaces should be
structurally sound. If there are holes or cracks, they have to
be fixed first.
Cracks. We repair small
cracks by spanning them with strips of fiberglass mesh tape and
"painting" over them with a masonry bonding agent. There are
many bonding agents on the market; we use a product called
Multi-Bond (Carson's Coatings). It's somewhat flexible even
after it dries, and it has a tenacious bond. If you put this
stuff on a window, you could plaster over the glass and it
would not come off.
This method is fine for repairing minor cracks that result from
settling or earth tremors. It will not work on cracks that are
caused by underlying structural problems. There's no point even
thinking about stucco until the structural repairs are
A good bond. The walls should
be clean before you apply color coat. We power-wash the wall
with plain water to prepare it. It's possible to put color coat
over previously painted stucco, but it requires extra
When I first started plastering, there were subs who would
sandblast the paint off existing stucco buildings. This
produced an excellent substrate, but it was incredibly messy
and posed an environmental hazard because of the old lead
paint. Nowadays we use a power washer to clean the wall and
knock off any loose paint (Figure 8).
Figure 8. Color-coat
stucco will readily adhere to an existing layer of the same
material. This wall is being power-washed to remove dirt that
would inhibit the bond.
Once the wall is dry, we coat the entire surface with bonding
agent. This ensures the color coat will stick, and it glues
down any loose paint edges. It's not cheap: A five-gallon
bucket of bonding agent costs about $100, plus there's the
labor to put it on. We do it because it's better to spend a
little extra on prep than to hear from a customer whose finish
coat is peeling off in spots (Figure 9).
Figure 9. Painted stucco
should be coated with a bonding agent before color coat is
applied. This wall has never been painted, so bonding agent is
not required, but the author's crew applied it anyway as a
"belt and suspenders" measure.
Uniformity. A color coat has
no trouble adhering to a brown coat, Foam Tite, or an existing
layer of color coat. Still, there are times when we will put
bonding agent on these surfaces. One of the hardest things
about applying color coat is controlling the actual color you
get. If the substrate is not uniform, certain areas may cure
darker or lighter than others. For example, the junction
between existing stucco and a newer patch may show through the
color coat because one area of wall has more suction (is more
absorbent) than another. If you want uniform color, you need to
apply the color coat to a uniform substrate. One way to even
out suction is to coat the entire surface with bonding agent
Figure 10. This wall was
coated with a bonding agent to equalize the suction between the
existing color coat and areas that were patched when the
windows were replaced.
Color and Finish
The customers may know the color and texture they want, but
unless they do stucco work, it's impossible for them to
describe the finish. So I usually ask them to point out a
nearby building that has the color or texture they want. I'll
then make color and texture samples to try to reproduce
Texture. Many different
textures can be created when the finish is applied. There are
pebblelike dash finishes, smooth float finishes, and a variety
of lightly or heavily textured trowel finishes. We try to
produce the finish the client wants. I point out that heavily
textured finishes will collect more dirt and grime than smooth
ones, but that irregularities in the frame are less likely to
show through a textured finish.
When I started plastering, customers expected a very uniform
finish, so that's what we strove to create. Nowadays it's
popular to do a more irregular "old world" finish. Many of my
customers want their homes to look like ancient Tuscan villas.
It took me a while to become comfortable with this type of
finish because it's against everything I learned as a young
Color coat is usually applied with a trowel (Figure 11). Every
plasterer has a slightly different "hand," so it's hard for two
guys to produce identical texture. I try to have the same
plasterer do all the color coat on any given wall. That way,
any transitions will happen where the customer can't see
Figure 11. Here the
author creates a skip-trowel finish by applying a second layer
of color coat over a partially cured layer of the same
A traditional finish coat is made from portland cement,
hydrated lime, sand-sized aggregate, and various additives. We
use LaHabra's Exterior Stucco Color Coat (714/778-2266;
www.lahabrastucco.com). The only things we
have to add to it are water and pigment, usually one box of
pigment per bag of stucco. The finish material we use is
available with either white or gray cement. We choose the type
of cement based on the color we are trying to achieve.
It's very important to mix consistent batches of material. We
always mix enough color coat to cover entire sections of wall.
Adding a little bit more or less water can alter the color of
the cured material. You don't want to run out of color coat in
the middle of a wall because the next batch could be subtly
different. This is less likely to show if you change batches at
the natural break points in the wall (Figure 12).
Figure 12. Each batch of
the finish coat should be large enough to cover an entire
section of wall. The wheelbarrow of colored material (left)
will provide enough material to cover the uncoated wall to the
left of the completed section in the photo at
Acrylic finish. Acrylic
coatings can be used in place of traditional portland cement
color coat. The acrylic products I use come premixed (including
liquid and pigment) in five-gallon buckets. The material is
factory-mixed so the color is very even. It's also very
flexible; it will span small cracks. The best thing about
acrylic is that it's available in darker, more vivid colors
than you can get with conventional color coat.
I don't push acrylic finish because, unlike traditional color
coat, it is not permeable to moisture. It doesn't happen in
every case, but I have seen buildings in which trapped interior
moisture caused paint or acrylic coatings to pop off.
One problem with conventional foam-based trim is that it's not
very impact-resistant. The foam is soft, and since the color
coat is not very hard, it doesn't take much force to dent the
trim. It's a bad idea even to lean an extension ladder against
windowsills and casings. There are certain subdivisions in this
area that restrict the use of conventional color-coated foam.
They might allow you to use it up high, but not down low where
it's likely to get dinged. This problem is especially common
around garage and entry doors.
One option is to use cast-concrete moldings (Figure 13). It's
also possible to apply full, three-coat stucco over foam or
wood blocking. The finished casing will be as thick and strong
as the surrounding walls. This method was popular at the
beginning of my career but died out in the 1980s because it was
too labor-intensive to compete with EPS trim. The most
cost-effective solution is to use foam but to coat it with a
harder material such as faux stone.
Figure 13. Cast-concrete
trim is produced off site and delivered ready to install
(left). It's very heavy, so it must be mechanically fastened to
the wall; note the metal straps that extend from the edge of
the pieces (right).
If a client is concerned about damage, we'll typically use our
faux stone product. We had a sample of our "stone" material
tested, and it was impact-rated at 2,600 psi. It's not as tough
as cast concrete, but it will stand up to just about anything
short of a baseball bat or hammer.
Don Thorvund has been in
the stucco trade for more than 20 years and is the owner of TNT
Plastering in Fremont, Calif.