Ask the pros-
April 2010

By Reggie Bullard





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?
Chipping painted stucco Applying bonding coat
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.

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