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Community and Q&A

Vapers barrier under carpet

Krissykrissy | Posted in General Questions on

I am renting a basement apartment an it is very damp it isn’t possible for us to put hardwood it is out of our budget so I have bought a carpet an was wondering if I should put a vaper barrier under the carpet to try an stop the dampness coming thro the carpet….help we are o  a fixed budget an also have a very low ceiling so subflooring isn’t possible either

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  1. Jon R | | #1

    Yes, preferably fully adhered and then covered with a thick, air impermeable carpet pad. And run a dehumidifier to maintain about 50% relative humidity (lower than normally recommended because of carpet's cooling effect). Works well for me (no odors).

    If I did it again, I'd use wall-to-wall rugs (easy to remove in case of water problems).

  2. Expert Member
    Zephyr7 | | #2

    Carpet on a cold, damp floor will usually result in musty smells from the carpet. Have you considered putting in an insulated subfloor as is frequently discussed on this site? You basically lay down a layer of rigid foam over the slab and then plywood over that? You can save money using reclaimed foam. The other option would be a vinyl laminate floor.

    If you do go with carpet, make sure to use a very low-pile carpet.


  3. GBA Editor
    Martin Holladay | | #3

    There are two ways your carpet can get wet:

    1. If there is no layer of polyethylene under the concrete slab, moisture can be wicked from the damp soil under the slab to the top of the slab.

    2. During warm, humid weather, moisture from the interior air can condense against the cold slab (or against polyethylene installed above the slab).

    Installing polyethylene above the slab helps with Problem #1, but provides no help for Problem #2.

    1. Expert Member
      Dana Dorsett | | #4

      The amount of dehumidification necessary to avoid #2 varies depending on the local soil/sub-soil temperatures. (What works Miami won't necessarily work in Maine.) Where is this basement located?

      1. Expert Member
        Zephyr7 | | #5

        It also depends on moisture in the soil which is related to water tables. I have that problem in my own house -- I have spring fed ponds and streams on my property. Very pretty. The downside is the ground is unusually moist resulting in higher amounts of moisture entering the basement making sealing and insulating more important. I've been working to resolve that.


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