I am updating my 60’s house with stucco. The structure is painted masonry block. I thought that stucco brown coat would bond directly to the block, or at least with a bonding agent. One of the stucco contractor bidding it says he’d have to powernail lath as the block is painted and stucco would fail to stick. Paint is very sound. He’s not using portland cement stucco, but what he calls “extreme” stucco. Powernailing lath makes it pricey. I live in Arizona. Any comments, alternatives and experience would be helpful.
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Replies
Stucco or colorcoat will stick better to block if it is wet down first. The brown coat is for losing the block texture. Sometimes block wall are painted to seal out the rain, if you have large overhang (eaves), your OK.
When stuccoing anything, dont let direct sunlight dry it out too quick, same with dry heated wind (common in Arizona).
El Rey (made here) has come up with a bonding agent that they claim will allow stucco to be applied over paint. Never used it, don't know if it works.
If it was my house, I'd rewire it. It'll give you an opportunity to apply some rigid insulation...which all those AZ block houses can use. Or, you could investigate sandblasting the paint off.
I'd do one or the other. I don't trust stucco over paint.
ShelleyinNM
R-Dog,
It would be best to re-lathe. It's true, there are primers that stick to paint, but then the stucco still only has whatever bond the paint has to the block if you do that.
Re-lathe on CMU really isn't that big of a deal. No need to power-nail anything. One-inch masonry cap nails and a 28 ounce Vaughan rig-axe works just fine, not but a little bit slower than regular nails in wood.
If your stucco sub balks at this, it might be worth shopping around.
DRC