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Carpet on concrete..what is proper installation?

October 17, 2008

Want to install carpeting on cement slab foundation, at grade level. We see the dri-core prouct but will add expense, extra time and labor and not sure if we need it.

Some say we need a moisture barrrier others say we do not. Is this a special pad or will the moisture barrier be something we install first, then the padding, then the carpet?

Also, must be glue the moisture barrier down to floor or can all be just laid down?


Comments (9)
  • floorguy

    Say what????? Is this in a basement or something???

    Nail your tackstrip and roll out the cushion, Glue and tape the cushion and go cut your carpet, put the seams together where you can and stretch to where you can't seam just yet. Put those seams together and continue stretching, trim it in and tuck the edges and be done with it....

    I have never placed a moisture barrier down when installing carpet. Your trying to over think this way too much.

  • slc2053

    No basement..this is a concrete slab foundation....at ground level...the concrete was poured 6 months ago..on some days it "sweats" which tells me there is still moisture in the concrete..I haven't done the moisture test yet (taping plastic down and giving it a day or two to see if moisture is there, but I will). Some say, like yourself, "don't worry about it" others say that you don't want that moisure soaking into you carpet pad then into your carpet..you may never see it but you don't want that trapped in your carpet and potential mold developing as a result.

    Not "overthinking"....just asking a question as what most do here when they don't know the answer or are hearing conflicting advice....

  • floorguy

    Your slab sweats because it is below dew point temperature, not because the concrete is 6 months old. You have a high humidity situation, not a concrete moisture problem.

    When you have a surface that is below the dew point temperature it will form condensation on that surface. Just like a cold glass on a humid day. It isn't the water in the glass condensing on the out side of the glass, it is because the outside of the glass is cool, and below dew point temperature and condensation forms on the outside of the glass. This is also the reason windows sweat, in the winter time. The window is below dew point temperature.

  • slc2053

    Makes sense...but if I do the plastic to the floor test, and moisture forms ..then do I have a moisture problem? If so, you're still saying it's ok to put carpet padding directly on it?

  • floorguy

    The mat test can be skewed because of high humidity. If you want a definitive moisture test, drill a hole ½ as deep as the slab is thick and insert a humidity probe. above 75% and you have a concrete moisture issue, but I still would not cover it with a moisture barrier, as carpet and padding are able to breath.

    Stretch in Carpet is not effected by high concrete moisture vapors, unlike something that is directly bonded, with adhesives. It is the adhesives or wood flooring that are effected by high concrete vapor emissions.

  • mnnie

    Hello. No, you don't put a moisture barrier down first. I was told that this could lead to a mold problem between it and the concrete. I looked at Dri-core, and finaly decided against it too because it raised my floor 1" which meant I had to raise a couple doors. Too much work and money! Yes, you can put the pad directly on the concrete. I just had this done. I used a very heavy rubber pad, and I was pleased that it has done a good job of insulating the cold concrete floor.
    I hope this helps!

  • jbranch

    I would not use rubber pad in a moisture prone area because rubber pad is not really rubber. It contains a lot of fillers that won't like the moisture. I am sure that floorguy knows what he is talking about, but I work for a carpet mill and in the situation where you need to file a claim for a quality issue with the carpet or the pad, the moisture could void your warranty (not real sure how much moisture you are talking about). I would recommend fixing the moisture problem then put down the carpet and pad. Wouldn't moisture lead to mold? With all the bad stuff out there about mold, I would fix the moisture for that reason alone.

  • PRO
    JJA llc, Jody Johnson Architecture, llc

    do you have to use glue for carpet on a concrete floor?

  • lala674

    Is am also in the process of installing carpet on concrete floor. I'm turning out finished garage into a "man cave" for my son who just turned 22 over the weekend. I purchased Berber carpeting and a roll of that blue on one side, mint green/rainbow padding on the other. One wall of the garage is insulated (wall covering garage door) other walls are not. No leaks or moisture problem, just worried about how cold it will be in the winter. Garage is 12x20 and he has a very good space heater. Should or do I have to lift the floor up before installing the padding/carpet? Is it absolutely necessary to do this? Single mother of three with two in college and a son who needs his own room, so any suggestions will be greatly appreciated!!


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