Applying Stucco to Homemade Concrete

While I acknowledge the difficulties with the underlying material, there would not be a "permanent" solution in any case.

Stucco, no matter the base, is rarely good for more than a decade.

"elevation 8500 feet"

Don't know the locale, but at that delta, stucco is not the way to go for adverse environments

Best O Luck

We use it extensively in New Mexico at those altitudes.

'Course you DO want to apply in summer months.

Wrap the concrete with felt or Tyvek and build a frame of two by fours and attach to the old concrete. Cover frame with mesh and apply new stucco, two base coats then a color coat

I think Guru has the right idea, the stucco is only as good as it's base/what is applied to. Having said that if the concrete is in such bad shape is it worth covering why not replace the concrete wall and then stucco!

I think you are both on the right tack, then the concrete can quietly crumble away inside the exterior wrapper (albeit at a slower rate)

What do you think they have done here in New Mexico for hundreds of years? They sure as hell didn't build 2x4 walls around their adobe and 'homemade concrete' walls befor applying stucco to them. If the existing stem wall matrix is weak, you should obtain a commercial bonding agent - Eucoweld, Sika, etc. - and then apply a suitable thickness of Portland cement plaster to the stem wall, over the bonding agent, and then apply the stucco.

If you are close to Santa Fe, contact Crocker Ltd. for further advice.

Yes of course you are correct. The scabbing of 2x4's was a gut reaction to a scenario in which cosmetic applications are routinely applied forgoing a more intense (expensive) repair.

Hello shawdog2,

The problem using stucco at that high an elevation would be freezing and blow-off. And stucco does not tend to have a good 'shelf life' anyway.

You say you are applying stucco to a cement wall? Why? If the cement wall is 'sound' why not just paint it and there would be no likelihood of a blow-off?

bb

Once cured, cementitious base for stucco does not freeze. The finish course is a synthetic, flexible material that has no freeze-sensitive components and it does not blow off. The products used have no aspect of "shelf life". You should try to focus your comments on something that you have knowledge of.

Hello Doogleass,

Many thanks for the insult, I was not expecting that. Still no problem.

The 'shelf life' as most people would understand was a JOKE!

I meant that, as has been said before on this thread, stucco on the whole does not last as long as the life of the basic building structure, whether that be brick or cementitious, and or concrete material.

I was a builder for 20 odd years so I think I can give my opinion when I try to help you, as I know my opinion is brought from many years of hard work. It may not be at over 8000' but non the less. And as perhaps other posts on CR4 will confirm, I am not ignorant of this subject. However, if you want to insult rather than say, 'in your opinion' I am not qualified to help you, then carry on! Or go on to explain what you have done and what methods you have used, instead of insulting me or anyone else............

You will find not much help from now on and for any future requests with your attitude.

bb

Sounds like you are trying to make the best of a poor situation.

First step I'd try would be to stabilise the "concrete". If it's porous, then it should absorb materials like "PVA" that can then cure inside the structure and provide an increased strength. (There is a product in Aus called "bondcrete" that I would consider, but I think one of the North American subscribers has already suggested some materials.) (Obviously you will not make it as strong as modern concrete but it might help to stabilise the substrate.)

Then I'd coat the exterior surface with a "render" using good cement and clean sand at 1:3 ratio to fill all low spots and have minimum cover around 10mm. (TWood float, not steel so surface is still rough, but using a relatively watertight mix.)

Then you can apply whatever external treatmetn that you wish. Paint, whitewash or whatever.

Shawdog2, Just an Engineer is pointing you in the right direction.

If we can even refer to your substrate as "Concrete", a key element is to Stabilise the host material prior to any coating application. Testing for porosity, density and cement content will be all telling. Object is to introduce a chemical that will form a solid inside the existing wall. If you can waterproof the host material, this should prevent moisture and contaminates from entering the matrix. This will also prevent the wall internal chemistry from migrating out to the surface which may be compromising your stucco bond properties. Once you have a Stable host surface a stucco product might have a chance at longevity.

Stucco, by some of the comments, is taking a bad rap. Stucco, being very cement rich is a very good and easy product product to Stabilise. It's high alkali content promotes a very rapid reaction to fill the gel pore/ capillary system with a solid. At that point it will be waterproof, will not be subject to freeze thaw conditions and most importantly, will have a chance at a bond that won't break under the environmental conditions discussed in this thread.

Also of interest to you may be the fact that your stucco (Once Stabilised) will not develop hairline shrinkage cracks and can be painted in 48 hours. Key to your issue is to provide a Stable concrete wall host surface before you do anything else. The rest is easy!