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damp basement floor: do Dimpled Membrane or “garage tiles” with moisture channels work?

anaxagoras | Posted in General Questions on

I have a 120 year old house in Southern New England, while the basement doesn’t flood, there is no moisture barrier under the slab.  During heavy rain storms  (once or twice a year at most) the walls of the basement darken, and there is some efflorescence on the walls.  A couple of times I’ve had things on the floor that wound up with mold under them as well.  So definitely moisture is weeping up.

I don’t see an easy fix here, short of excavating my foundation and putting down a moisture barrier.  I know i will never be able to have a “proper” finished basement without spending more than what my home is worth, and I’m ok with that.  I’m just trying to make my basement more habitable for a workshop and home gym. 

My biggest fear is putting something down that will cause mold to grow!

2 options i’ve come across are using a dimpled membrane and then throwing down rolled rubber gym flooring on top.  Or using click lock plastic tiles that are elevated and have channels for moisture, such as the norsk pvc tiles.  What are your thoughts on these systems?  I know there’s not much airflow under them, but i assume it’s enough to allow the moisture a path to escape?   Do you think these will work for me?

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  1. Aedi | | #1

    Building Science Corporation has a good article on the problem and its solutions here:

    Dimpled membranes work differently than you might expect. Moisture is purposely trapped, but in a way that actually prevents additional wetting (see the end of the article for details). Mold is not a worry for these systems, at least not that I've ever heard of.

    I am not familiar with the PVC tiles, so I cannot comment on that solution. PVC is bad from an environmental perspective though.

  2. Jon_R | | #2

    You want a fully adhered vapor barrier then flooring that is at least somewhat vapor permeable or has some airflow (such that the drying rate exceeds the wetting rate).

  3. FluxCapacitor | | #3

    I have a similar issue and by dumb luck may have taken some of the correct countermeasures suggested in Jon and Aedi’s very informative links.

    In the spring I get some damp spots around the perimeter of the basement. Occasionally a little water will be visible in the perimeter French drain which is just a 1” deep groove around the perimeter of the basement leading to a sump pit.

    Even with a dehumidifier my stuff would get musty. About 2 years ago a started to add a bathroom and recreation room. it’s almost finished.

    I tiled the bathroom last year. It was in the driest area of the far no signs of moisture.

    For the most moist basement area I used vinyl plank flooring over plastic DryBarrier tiles. This combination functions as a moisture barrier with air channels and is advertised as not supporting mold growth (in theory).

    The DryBarrier and vinyl plank has only been down for a couple of months but I’m getting the impression it’s going to work really well. Currently there are zero mildew smells on the area rug or anywhere else.

    If you decide to use use a dimpled product or DriBarrier type product your concrete floor needs to be very level or its likely to make clicking sounds and feel squishy. Rolled rubber gym flooring might be ok...IDK.

    I did not properly level my laundry room and it clicks like crazy (I’ll redo next year). Then I used 12 bags of self leveling concrete in the recreation room (pictured) and it came out solid even with the dry barrier underneath.

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