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Laminate Floor Over Concrete Basement

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  • Laminate Floor Over Concrete Basement

    I have a potential remodel or I should say finish what the builder is leaving hanging for client project that would involve 1000 SF of laminate flooring in a new homes unfinished basement.
    Concrete was poured last fall and has been enclosed by house for nearly that long.
    Question is whether we need or would it harm installation to put a poly vapor barrier down?
    The laminate flooring is factory backed with foam padding. I realize that the floor itself will act as a vapor barrier to some degree.
    Other factors here are that the floor is a hot water tube radiant floor and the customer is really requesting a vapor barrier as she is an enviromental consultant and is concerned about future (none now) radon outgassing levels. She has a pipe under slab already to capture and could vent gasses if they detect radon level sufficient to warrant venting in future. She's going to monitor yearly.

    I'm thinking here that everything, the floor, its foam back and potential vapor barrier are all going to outgas (as well) to some degree, maybe worse than the radon :) But I'm wondering what everyone thinks would be warranted here.... Poly barrier under and seal the seams with tape all around, even at the expansion joint perimeter -or- is this barrier even necessary and/or desired over a radiant floor ? We've done laminate floors over tube under subfloor (between the joists) applications but never where it is going directly in contact with a radiant slab. Most homes here are baseboard radiators but radiant slabs are becoming very popular in the new homes.
    Thank you in advance for everyone's insights.


  • #2
    Re: Laminate Floor Over Concrete Basement

    Dave, Over concrete, definitley put down a vapor barrrier, tape all seams, go up walls at least 3" and cover plastic with baseboard trim.

    Laminate over concrete can be a real funny animal to control, I would call the manufacturers tech support Dept and explain your situation to them, let them tell you what methods should be used to keep the laminate with warraunty specs.

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    • #3
      Re: Laminate Floor Over Concrete Basement

      Thanks Jonathan I am going to give them a call. First I had to find out what brand it was (Alloc- Domestic Series). So far I know that they recommend the vapor barrier and that it is spec'd for over radiant floors. I definitely want floor in right the first time. This customer has had too much trouble with her builder all ready so I don't want a bad reflection on us ! :)



      • #4
        Re: Laminate Floor Over Concrete Basement

        Good. Laminate flooring in bsmt's. can be very dicey; I've seen them go bad even when everything was done "right".

        Another opportunity for you getting stuck in the hard place is the performance of the radiant. Whoever engineered it (if it was even engineered), may or may not have factored in wood flooring. Wood flooring w/a foam back would need substantially more tubing than a concrete or tile floor; you have to run slightly cooler temperatures under wood, and offset that w/more tubing. There's other variables to figure in, but......

        Point being, the radiant is a complete unknown; I've seen some monster screwups w/bsmt. radiant when the customer decides to go w/carpet or wood instead of tile; floor won't warm up because the flooring is acting as insulation. Beware, and get this spec'd out from the heating engineer (if there even is one). You could find yourself holding a lot of loose ends the other trades left hanging.
        Kurt Mitenbuler
        Chicago, IL


        • #5
          Re: Laminate Floor Over Concrete Basement

          Kurt, that is a very good point about the specing of the radiant system to the intended floor. I know (now, after research) that Alloc specs no more than 80 deg F for maximum allowable surface temperature. They are also very specific about bringing floor up to temperature over a time period if it hasn't been heated yet as well as acclimating laminate, expansion joints, concrete level-ness etc. as well as installation of vapor barrier. Calcium chloride test readings are spec'd as well.
          All things to discuss with customer (not builder) over phone and let them figure out.
          As usual reading the manufacturer's instructions yielded a ton of info, but it helps to know how much of a pain these floors can be or what can go wrong ahead of time.