Hi All
I am planning on stuccoing a block wall that surrounds a crawlspace. I want to paint the stucco. My main concern is the mortar joints showing through the paint. Do I need to do all 3 coats of stucco or will the paint hide the mortar joints. What is the fastest way to do a good job on this? What kind of paint will work best?
HC
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HC,
Lemmee get this straight.
You've got a CMU wall, that you are going to stucco or parge. That is, apply a thin coat of cementuous product over to give it the appearence of solid concrete.
Then you are going to paint it.
The parging will cover all mortar joints in the block wall. You are going to do a standard second or brown coat with the stucco material. This brown coat will be trowel finished smooth.
You may do a third, color coat, to the stucco.
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If you color coat, why do you want to paint? The color coat will outlast any paint.
If you just brown coat, there will be nothing to bleed thru the paint.
SamT
I guess what I would like to do is only do one coat of stucco(mortar) then paint. Skipping the extra coats. Since I am painting over the coating should this suffice or will I have problems.
HC
Sounds ok to me.
In normal stucco construction, the purpose of the scratch coat is to provide a rigid layer. TheCMU wall is already rigid, so you don't need the first coat.
The second, or brown coat levels and smooths the stucco. You do want to do this to hide the mortar joints.
The third, color coat, provides some texture and color. Since you are not worried about texture, you can substitute paint.
How good do you want this wall to look? Paint will telegraph every dimple and pimple in the 'crete.
SamT
I dont have an answer but ,another question, which may be the same one you are asking. I see a lot of block walls and foundations that have been parged or stuccoed and the mortar joints telegraph right thru. Especially on a cold morning. This just doesnt look so special and I wonder whats the easiest way to remedy that?
Mc,
The fact that it happens mostly on cold mornings indicates that the voids were not filled.
The reason for telegraphing all the time may be because the wall was not wetted and kept moist during the application and curing process.
SamT
I would expect two coats before painting to be sure.There are two potential reasons for telegraphing.One is that there is a difference in mass at the mortar joints or moisture from opposite side or within ( all problems of there own kind). That mass difference leaves teh telltale condensation.The other is when the modern premixes are used instead of standard mortar and not applyed thick enough, or evenly, leaving a shadow line all the time. Paint will hide neither of these. the thickness of the second coat or a third will temper the mass and even the joint. I tend to agree that the block wall serves as the scratch coat well enough. Using Thorocrete slurry rolled on 'might' work as both second coat and paint in one step, but I wouldn't bet the house on it.
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