Our house has a damp/musty smell to it when you first enter. Once you open a window/door the smell usually dissipates. In May (Chicago-land) the humidity in the house is about 30% upstairs and 40% in the crawlspace while dehumidifiers run on both floors.

We noticed that of our crawlspace dirt floor is moist, almost mud-like, along the front side of our house. See picture below. The floor moisture creeps forward a foot during heavy rains, and recedes a foot during dry spells, but almost never disappears entirely. The rest of the crawlspace floor is dry.

damp crawlspace floor

We notice no cracks in the foundation wall, and no water lines running down the wall. We recently installed a French drain to reduce the amount of water hitting the front of the house (the floor dampness existed before installing the drain). The gutters dump water into a pipe system that the sump pump uses, and shouldn't be dumping water at the foundation of the house.

Our sump pump runs routinely, about every 10 minutes during rain and every 30 minutes during dry spells. Ground water is always slowly pouring into the sump pit.

Is this damp ground something to be concerned about? Can it be fixed? Is it possible that the damp smell comes from the crawlspace floor moisture, or from something else? How can we get rid of the damp smell? We want to hire mold specialists to test and clean the crawlspace but are afraid their work will be wasted if we don't eliminate the source of the moisture first.

  • check out my link in the answer how to water proof a basement.
    – Ken
    May 10, 2017 at 2:54
  • Do you live on a slope or near a hill?
    – Lee Sam
    May 10, 2017 at 6:17
  • 1
    The water is coming from somewhere. If it's only along the front of the foundation, it isn't a high water table, that's where the source is. Feeding your rain gutters into your sump system isn't a great idea. They can collect more water than the pump can move, so it has to go somewhere else. If the pump runs only every 10 mins during a rain, not much of the rain gutter water is feeding it. Make sure the gutters and downspouts are clear of debris, and the gutters are secure.
    – fixer1234
    Jan 28, 2018 at 21:41

1 Answer 1


You will need to seal the basement walls and the basement floor to accomplish this.

I have seen the dirt removed from around the face of the basement walls and then the walls sealed and the dirt returned - generally it is a trenching around the basement wall of the house - but I have only seen them do one wall.

There is another way to do it that is easier and works from the inside of the house:


  • I disagree with a couple of "This Old House's List": 1) I've found that putting "waterproofing cement" on the INSIDE of wall is useless. By the time moisture reaches the inside of the wall, the water pressure will "push" it through the cement barrier. To stop moisture from coming through a concrete wall (or especially a masonry wall) it must be diverted away from the wall with a perf pipe encased in drainrock. 2) They didn't even mention installing a moisture barrier on the outside of the wall. 3) Install perf pipe (frenchdrain) BELOW the slab a few inches on the outside of the wall. You
    – Lee Sam
    May 10, 2017 at 6:03
  • You can't believe the water pressure of at the bottom of an 8' wall .. Water will be pushed through any crack, as it is in your case at the cold joint between the wall and slab. The only way to stop the leak is to get rid of the water. Where I live, we have a high water table and when we pour basements, we pour a "water stop" (a rubber gizmo with rubber flanges that set in the concrete) between the wall and slab, plus install a french drain BELOW the top of slab. Your water is being pushed in...when it rains hard, the water table rises.
    – Lee Sam
    May 10, 2017 at 6:15
  • @LeeSam he is in Chicago not Florida. Building in FL or a very high water table environment - I would imagine a builder would use a sealing around the outside as they build the house (or strongly advise against a basement - they are extremely rare in FL). Regarding an existing home I have only seen one example of sealing from the outside; they did one wall. The ops issue appears to be one wall. So I provided both examples for the op to choose from.
    – Ken
    May 11, 2017 at 18:44
  • 1
    Florida??? Who said Florida??? Regardless of where you live, sealing the outside of the wall and installing a perf drain is best. When you let the water come through the wall and then try to stop it, it's way way more difficult.
    – Lee Sam
    May 11, 2017 at 23:39
  • Did anybody notice this has a dirt floor? Sealing the walls from the outside will be quite expensive and if the problem is a high water table it will start coming up more in the dirt, with there always being moisture I would suspect there is a small spring causing the moisture because it is there year round
    – Ed Beal
    Jul 20, 2018 at 15:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.