Robert Lamoureux | Temporary and permanent fixes for spalling

Robert Lamoureux
Robert Lamoureux

Question No.  

Hi Robert,  

I attached a photo for reference, hoping you can tell me what the problem is. The building where this photo was taken was just painted a couple months ago and we are already seeing this issue once again. Whatever it is seems to have crept up to the window ledge. Is this spalling? Can something be done here? There are no sprinklers or pipes in the vicinity, so what could this be? Please advise.  

— Laurie 

Spalling occurs when the surface breaks off a concrete type of material. Water introduced from sprinkling or from underground allow minerals to bleed through the surface. Courtesy photo

Answer No.  


I know how frustrating it can be do have the area cleaned up and thinking an issue will be gone. I’m sure the pressure washing prior to painting helped eliminate this at the time, but this is efflorescence caused by minerals in the water. Spalling is when the surface breaks off a concrete type of material. If the water is not being introduced to the surface somehow such as with sprinklers, then it must be coming from underground. This is similar to a property I worked on not that long ago where this exact situation happened, and we had to repour garage floors and install proper vapor barriers. What happens that causes this is, the minerals bleed through the surface because concrete is porous, and present just like this. The only low-cost resolve to this would be to clean it as it appears. The permanent fix for this is to replace the concrete and put visqueen (heavy duty plastic) under the slab just like we do when building a new structure, to prevent this very thing, or worse, from happening. Good luck, I hope this information helped with understanding. 

— Robert 

Robert Lamoureux has more than 40 years of experience as a general contractor, with separate licenses in electrical and plumbing contracting. He owns IMS Construction Inc. in Valencia. His opinions are his own, not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor after that contractor has made a thorough visual inspection. Email questions to Robert at [email protected]. 

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