My house has a daylight basement along with some areas that is finished crawl space. Basically instead of dirt there is slab in the crawl space. I bought the house a few months ago and the crawl space looked super clean. The inspector did call out was one small area about 2-3 feet where there was some moisture and efflorescence. See below

enter image description here

Last year my area had the highest rains in years and hence, the seller believed that there was moisture. He mentioned that it had never happened earlier and there were no other indications in the crawl space. The seller put hydraulic cement in that area (in the internal part of crawl space). I bought the house thinking that it may not be a problem again. However i have been concerned and hence have been keeping an eye on the area especially after the recent heavy rains. Lo and behold one day i see the hydraulic cememt darker in a couple of very small areas. I did not see water but the dark areas indicates moisture. Now that those areas are becoming dryer i think i see efflorescence.

It seems like the hydraulic cement is not helping. Also seems like i may have to get a professional but I am not sure i can afford any work now.

My questions are:

  1. If the problem remains contained in that small area or repeats at a much lower frequency (1-2 times a year), do i need to resolve this problem immediately? I understand that if this spreads or keeps on happening than i need to get it solved. How worried should i be if it remains in that small area or happens very infrequently?

  2. Can I do anything from inside. like applying another material to prevent water from seeping? The hydraulic cement is not 100% as can be seen above.

  3. It seems like the proper way to fix this is to get a contractor, who will dig from outside and build a solution to keep the water away from the foundation? What is the approximate cost I am looking at here. Talking to a friend at work, he said it could be easily 5K.

Any other thoughts or help ideas?


I posted the inspectors picture in the my post above. Here is the latest picture after the hydraulic cement and efflorescence i saw few days ago. Is this minimal. This is about a 2.5-3 ft


  • The ONLY way to permanently solve this problem is to identify a change a poor surface water drainage pattern. No amount of “plugging the crack” with any product will solve the problem, the water must be diverted before it gets there.
    – Tyson
    Nov 25, 2017 at 14:02

2 Answers 2


Effervescence of concrete of your type is a reaction of the added concrete. It is generally found in acidic compounds. I recommend using some ammonia over the entire concrete surface with no added water. Use a mask please! The ammonia will neutralize the acid and in many cases solve the issues. I see this on my acid stain projects and that Is how we mitigate it. Now if the ammonia comes in contact with any metal surface it will cause rust so avoid electrical and metal surface...AND WEAR A MASK!

  • Thanks Cobra. I am guessing you are suggesting the ammonia so if the moisture enters the crawl space the efflorescence wont happen? Is efflorescence itself a risk that i need to get rid of? My major concern is that efflorescence is a symptom of the issue i.e. mositure, so when you say "it will solve the issue" you mean it will take care of the efflorescence but not for the moisture?
    – user70309
    Nov 27, 2017 at 6:51
  • No you need to find the source of the moisture and fix that first. So my advice is to hire a General Contractor to diagnose the issue. Ammonia is just a means of treating the symptom and not the cause. Nov 28, 2017 at 0:10

I think it is premature to start planing a repair. I would take a wait and watch posture. I don't see any damage being done. P.

  • OK. Thanks P. When do you think would be the right time. I was told that efflorescence in itself (without causing mold :)) will take decades to cause foundation issues. Is that true?
    – user70309
    Nov 27, 2017 at 6:56
  • I see other good comments here. I am going to defer. Not exactly my primary field.
    – Paul Logan
    Nov 28, 2017 at 5:04

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