Interior Plaster Efflorescence
I have recently purchased a 40 something year old wood framed stucco house with plaster interior walls. One side of one wall is permanently in the shade. Around the top of the windows on this wall the plaster is bubbling. It doesn’t seem to be direct water infiltration, but efflorescence. The exterior stucco and the caulk joints around the windows seem solid. I’m guessing that when the stucco gets wet, it takes a while to dry out because the wall never sees any sun and this is causing the wood framing around the window to draw moisture inside. I was thinking of applying a clear water sealer around the exterior of the window. Will this work or will it cause further problems? If it will work, what product would be most effective and how far around the window will I need to seal? I’m used to wood siding and have little experience with stucco.
I'd be leery of sealing the stucco. Properly applied stucco should be waterproof, if it isn't, there is something wrong that no amount of sealer will ever cure.
I'd have a competent professional in your area take a look at it. Water intrusion can be a real problem, best to fix it right away and properly.
Do you live in an area that gets an occasional heavy snow ?
If so, don't rule out water infiltration caused by ice dams.
Plaster veneer on board or real plaster on lathe?
Insulation in wall?
There is a possibility that this is related to condensation
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