Should we seal our concrete basement floor before putting flooring on top? Is there one that's low or no VOC?

Asked by Joan Cohen
Livingston, NJ

We will be installing a floating floor in our below-grade basement, so we can use it as a family room. Currently, there is only a fairly new concrete slab in good condition; the walls are sheetrock over concrete block. The basement stays dry (we have a sump pump), although the humidity level is a little higher than we would like. We'll be putting in a dehumidifier to control it. The flooring is Easy Loc (Marmoleum). We know we have to put down a 6 ml vapor barrier but should we also seal the concrete to further reduce the amount of moisture? If we do, what sealant could we use that's low or no VOC? There's not a lot of ventilation in the basement, just two awning windows. Thanks for any suggestions you may have.


Answered by Steve Pohlman

Oak Park, IL


August 22, 2011

Yes. You should always seal concrete with a moisture barrier primer sealer or paint.

  • Use low VOC or non VOC if possible. Any store should carry low voc concrete sealer.
  • Use a clear coat to ensure lower voc's than stains.

Be sure to close all of the holes in your drywall to decrease ventilation through the wall cavities and get better air quality.

  • And increase ventilation to the main rooms with an external fan. Use a bathroom vent fan with a hygrostat switch to control the flow as needed.
  • Make certain the sump pump lid is sealed and doesn't emit evaporated stinky humidiy.

If you get rid of the source of moisture by sealing everything the best you can, you might not need the dehumidifier any longer.



For more information:

Read Mary Cordaro's Q&A "I just finished my basement. Can you help me choose mold-resistant flooring?"

Read GreenHomeGuide's Ask A Pro article "Is cork a good flooring choice for a basement? Will my cats damage the floor?" for more advice about cork flooring.

Tagged In: basement flooring, basement moisture

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