Recoating
old
stucco,
painted
and
unpainted
I got smooth
finish stucco added on my textured
stucco
house 2 yrs
ago. It has started to
turn white in areas and
crumble
off the block
wall first and now
parts of the house. Anyway to
stop
this without
spending another $10000.
I want to
put a new finish coat over an
existing hardcoat
portland cement stucco house that has never been painted. Is this as
easy
as cleaning the existing walls and putting on a new finish coat?
Painted stucco:
I just found your website. Thanks for all of the useful
information.
We have a house built in 1970. It has the coarse type of
stucco
on it (that looks like very, very coarse sand paper). It has several
layers
of paint over the top of it. The stucco is in fairly good condition
except
for some small cracks in a few places (California earthquake area). We
would like to have someone refinish the stucco by adding a smooth top
coat
to the existing stucco with a color added. Is it possible to just
smooth
on a topcoat over the existing stucco and paint? Or do we need to have
all of the paint and/or stucco removed prior?
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First.
wall is chipped into the old stucco about every
3-4" or so, enough
to give the new mortar a good bond on the old stucco basecoat. |
A
thin bonding coat is applied.
This is our normal
mixture of cement
and sand, mixed with a solution of half water and half bonding
admixture.
This mixture is real sticky and provides good adhesion to both the old
paint and old
basecoat. The surface is left rough for a good bond of the cement
finish
coat. |
Unpainted stucco:
We have been resurfacing a lot of stucco lately. It isn't too
complicated
if the stucco has never been painted.
If the stucco has never been painted, a new color coat can be
put over
the old finish by using an acrylic in the mortar like flex-con. Our
formula generally is using a half and
half mixture of acrylic bonding admixture with water and mixing with
the
dry finish coat mix. There are other methods, but this is the simplest.
Stucco finish will not bond to stucco finish without an
acrylic
additive or bonding agent. It will fail.
If the unpainted stucco has a rough texture, or patches than
would leave
the surface with ununiform in porousness or texture, a basecoat or
bonding
coat may be desired before applying the finish.
Our method of a bonding coat is using our usual mix of grey
portland,
lime and sand with the half and half acrylic and water mix. This mortar
can be troweled on thin (one eighth
to a quarter of an inch) and the surface left rough to receive the
finish
coat. The mortar can be roughed up with a rubber float or a brush.
Painted stucco:
Painted stucco is more work. We have developed a method of recoating
painted stucco that I trust to have a very permanant and crack
resistent
bond.
We first chip the wall about every 3 or four inches. The chips
provide
a rough surfave and open pores for the mortar to bond to.
The mortar must have flex-con or other acrylic for adhesion or
it can
fail. Chipping the wall is not new.
I learned this from an old plasterer. The walls I have seen on old
buildings that were recoated like this were easily scraped off. It was
better than doing nothing.
Using acrylic additives without chipping will work, but is
likely to
fail. Bonding mortar to a thin film of paint is like having a thin film
of faith.
Paint on bonding agents can fail, too, over time. The walls we
did 20
years ago or so are all peeling off.
We have also peeled off stucco that was done like this.
The method we use of chipping and bonding works real well, and
I trust
it to last as long as the wall behind it does. This is the use of two
good
methods that just aren't quite good enough on their own.
http://www.rtbullard.com/stucco/progress/progress110.htm
http://www.rtbullard.com/stucco/progress/lewis.htm
http://www.rtbullard.com/stucco/progress/jaime.htm
http://www.rtbullard.com/stucco/progress/kuhnsman.htm
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