Here in Northern California, three-coat stucco is the dominant
exterior finish material. It's been this way for years, so
there's a lot of available work remodeling and repairing older
Many of our jobs involve repairing existing damage, adding
cementitious window casings, and applying a new layer of color
coat to all or part of the building. A lot of the stucco houses
I work on were built in the '60s, when finned aluminum windows
were the norm. Typically, there are no exterior door and window
casings, and the stucco runs right up to the edge of the
opening. These old single-glazed aluminum windows are not
energy efficient, and after 30 or 40 years they're pretty worn
out, so window replacement jobs are common in this area.
Sometimes the contractor will tear out and replace the entire
window, and sometimes he'll install a replacement unit inside
the existing jamb. Replacing the entire unit always involves a
certain amount of stucco repair, which my company is often
called in to do (see
Replacing Windows in
Stucco Walls, 6/04).
When the replacement unit fits inside the existing jamb, no
stucco is removed, so there's no need to patch around the
opening. However, I may still land some work because the house
looks dated without casings. If the existing stucco is in good
shape, I can install new "stucco" casings right on top of the
Color Without Paint
Many older homes in this area have two-coat stucco, which
consists of a scratch coat and a smooth float-finished brown
coat. More often than not, these houses have been painted. The
new owners may not like the color and texture, and the walls
may have developed cracks. They could repaint, but that won't
fix the texture or cracks. My company gets called in to repair
the cracks and to change the color and texture by applying a
layer of color coat.
Color coat is common in three-coat stucco jobs. It's what you
get when you add pigment to the top coat of plaster. The color
coat is about 1/8 inch thick and will last 20 to 40 years if
Other homes in this area have three-coat stucco that has never
been painted. There is a scratch coat, brown coat, and some
kind of finish coat. The finish coat could be plain white or a
color coat. We're called in to repair cracks or because the
owner wants to update the house by changing the color or
texture of the walls (see Figure 1). It's a simple job to apply
a second layer of color coat to an existing stucco
Figure 1. A color coat
and casings were used to update the look of this 35-year-old
house. If it weren't for the old roof, the home would look
Even if the owner likes the existing texture and there are no
cracks, adding a color coat is better than painting. Painted
surfaces need to be maintained, and most paint jobs do not last
as long as color coat. Because stucco is porous, some moisture
may get past the stucco, hitting the building paper and
draining to the weep screed at the bottom of the wall. Any
moisture, whether it comes from inside or outside the building,
will eventually evaporate through the surface. But when you
paint stucco, it seals the surface — probably not well
enough to keep any moisture from getting in, but certainly well
enough to keep some of it from getting out. Sometimes the
building may not retain enough moisture to cause problems. In
other cases, though, it can be enough to pop the paint, rot the
frame, or support mold growth.
Before the advent of aluminum windows, wooden doors and windows
were installed fully cased, directly over the building paper
and wire lath, and the plasterer stuccoed right up to them.
Wooden casings were also popular in the 1970s, when they were
often installed over the fin but on top of the paper and
Wood casings are no longer common on stucco buildings. I work
on a lot of projects in which wood casings have been removed
because they had deteriorated or because water was leaking in
between the stucco and trim. It's our job to patch in around
the windows and install new casings that won't leak or
EPS foam. Standard procedure
on new construction is to install trim and moldings on top of
the brown coat but before the finish coat is applied. There are
a number of ways to fabricate casing, but the most common
method involves the use of an expanded polystyrene (EPS) foam
planton. The foam is glued to the surface of the brown coat
with a material that's similar to thinset mortar, then
reinforced with a layer of fiberglass mesh tape and given some
kind of cementitious top coat.
The trim can be finished to match the walls, or we can give it
a different color and texture. In some cases we'll put a smooth
finish on the walls and finish the casings to look like stone.
Similar methods can be used to refurbish existing buildings.
The biggest difference is the substrate: On new work you're
going over the brown coat; on old work, you could be going over
painted stucco, new brown-coat patches, or an existing finish
Some people hear the word "foam" and immediately think about
EIFS (exterior insulating and finishing systems). Foam-based
trim is different because it's not part of the wall structure.
There's at least 3/4 inch of stucco behind it, so the planton
is a purely decorative piece. It's the building paper and
flashings behind the stucco that keep water out of the
We use foam as the basis for casings, quoins, pilasters,
columns, wall caps, and other decorative elements. The foam
manufacturers use lasers to cut a wide variety of stock
profiles, and it doesn't cost much more to get a custom
The foam comes either raw or precoated (Figure 2). The raw
material looks like plain white Styrofoam, while the precoated
material is covered with a layer of fiberglass mesh and a coat
of polymer-modified portland cement. The coating is about 1/8
inch thick, just enough to fill the mesh. Whenever possible, we
buy precoated material because it saves us from having to apply
the mesh and the first coat of cement.
Figure 2. On this job,
raw foam has been glued to the wall (left). It will be covered
with fiberglass mesh and given a faux stone finish. It's faster
to use precoated foam; the material shown in the photo at right
arrived on site with the mesh and a cementitious coating
already on it.
Faux stone. On some high-end
jobs, we take the raw foam profile to our shop and coat it
several times with a mixture of ground limestone, portland
cement, pigment, and liquid polymer additives. The coating is
about 1/4 inch thick, and the finished pieces look like cut
limestone (Figure 3).
Figure 3. The author
creates faux limestone in his shop by applying a
polymer-concrete coating to foam profiles (top). His crew cuts
the trim in the field, glues it to the building, and mortars
the joints. When complete, it's hard to distinguish from real
We use a miter saw with a dry-cut blade to cut our "stone" trim
in the field. After the pieces are glued to the wall, we fill
the joints with mortar the same way we would if we were
tuck-pointing standard masonry. The finished casing looks like
cut, mortared stone. We can also apply a version of our "stone"
coating in the field. It goes over foam and can be finished in
a variety of colors and textures (Figure 4).
Figure 4. Though it
looks like weathered stone, this casing is actually foam that
was coated and textured in place. The faux limestone coating is
much harder than color coat, so the trim is at least as
impact-resistant as wood.
The foam casing material, even the precoated stuff, is soft
enough to cut with a handsaw. The cuts do not have to be
perfect because the joints will be taped and the surface will
be coated a couple of times before the trim is done.
We glue the foam on with Foam Tite (Carson's Coatings,
209/745-2387), a polymer-modified portland cement. It's mixed
and applied like a stiff batch of thinset mortar. We cut the
trim, butter the back with Foam Tite, and glue it onto the wall
(Figure 5). If it's new construction, we put the trim on the
brown coat. If it's old work, we apply the trim to the existing
finish coat. Trim should be installed only on clean, sound
surfaces. You can put trim on a painted stucco wall, but you
should apply a bonding agent first.
Figure 5. After cutting the
precoated trim to length (top left), the plasterer
applies Foam Tite to the back (top right) before
pressing it onto the building (left).