Concrete questions, pool deck rising


White powdery substance found on concrete slabs raises questions, slab rising with no tree in proximity

Good morning Robert,

I have read your column on the Dec 16th issue of THE SIGNAL that incentivized me to contact you. Coincidentally, we have an ongoing problem similar to your Reader LINDA M. who wrote in. When we bought our Home in Dec 2008, there was this white powdery material that blanketed the concrete garage floor and I observed that it is still surfacing to this day. I am not quite sure if this is caused by a water leak under the concrete slab floor and the source of it. I am very much concerned that this might create a serious foundation problem down the road. Who would you think to be the most appropriate professional tradesmen to handle and fix this issue or issues expeditiously and with expertise? I wanted to make sure to call the most qualified professional. I would very much appreciate your forthright advice.

Flora M.



The white substance you are talking about is efflorescence. This is not indicative of a leak necessarily, it could just be humidity. If this occurs during the rains it’s a sign of humidity and is quite common during the winter. If it’s there year round then it could be more. I don’t want you to spend any funds if this is all you’re talking about. If water is actually manifesting itself then you have a leak. I have sent you my local recommendation for a local plumber whom you can trust, he should be able to help if you believe you actually have a leak. Good luck.



Hello Robert,

I am a regular reader of your column in the Signal newspaper. I have a section of the decking around my pool that is rising. It is approximately 8’ x 8’ in size and bordered with used brick. The other sections of this decking design seem to be fine at the moment. I inherited the pool and decking when I purchased the home in 2014. I would guess that the “rise” has increased about 1/4” per year to now measure approximately 1.25” above grade at the corner. I suspect it is a tree root causing this problem, although there is no large tree closer than 30’ or more to this section. Puzzling … My question: Is this something your company might be able to deal with? I’m assuming that I would have to break out the existing concrete pad, find and correct the issue, and pour a new slab. If your company isn’t a good fit, can you recommend a contractor (or multiple resources) to deal with this? I’m not seeing any problems with the pool so far that might be related, so I’m thinking I might not needing to deal with this until the spring. Any thoughts or feedback would be appreciated. Best,

Ron M.



Good morning and thank you for being one of the readers of The Signal. Once you demo the concrete you’ll be able to see what caused the lifting of the slab. If you don’t see roots then the soil is no doubt the causation. We have a lot of expansive soil here in Santa Clarita that has caused lifting like this over the years in many areas. The clay in the soil is the source of this problem, as it gets wet it expands and causes the lifting as such. I’ve listed a local concrete contractor, please give him a call. Best of luck.

Robert Lamoureux has 38 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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