Question on underlayment for laminate

Discussion in 'Laminate Flooring Q&A' started by Alex216, Jan 7, 2020.

  1. Alex216

    Alex216 New Member

    The floor I'm working on is osb subfloor. I was laying down my laminate with an underlayment that also acts as a vapor barrier. I didn't realize this and from my research, this will cause issues later. The flooring store provided me with the underlay so I thought they gave me the right match. Will this be a problem? Should I just remove it and go buy an underlay without the vapor barrier? I've already lay down about 200sqft so I'd prefer not to redo it especially the joints are very fragile. I've already destroyed some trying to fix some other mistakes.
    It's the eternity laminate pad

    The laminate is quickstep naturetek if that matters
  2. There's not really an issue with using the underlayment with a vapor retarder on it over wood, UNLESS you're over a crawl space that doesn't have a proper vapor retarder underneath the subfloor and isn't properly cross ventilated. If you're over a basement that is reasonably dry then this underlayment won't hurt a thing.

    If that's the case what could possibly happen would be that moisture vapor from the crawl space would migrate up through the wood subfloor and then be stopped by the vapor retarder on your laminate pad and collect at that point between the subfloor and the plastic. Obviously water laying on your subfloor over time could create a mold / mildew issue and eventually lead to the wood subfloor rotting.

    If you are over a crawl space, I would advise you to continue with the laminate pad you have and then apply an appropriate vapor retarder underneath the sub floor if necessary. If you just stop using he laminate pad and don't address the underlying issue then the vapor coming from the crawl space could affect the laminate which would also be a problem.

    Again, this is only if you are over a crawl space that isn't properly ventilated and has no vapor retarder attached to the underside of the subfloor. For a basement it would have to be pretty extreme, like constant standing water for it to affect anything and even then it would depend on how much air movement occurs in the basement.
    • Informative Informative x 1
  3. Alex216

    Alex216 New Member

    Oh that's good to hear. This is over a basement and there's central air. Much appreciated for the response, I was thinking of worse case scenario with the mold.
    • Like Like x 1
  4. I have 15-18 year old laminate in my home installed with an underlayment with a vapor retarder over a full basement. My house was built in 1926 and the basement is "reasonably dry". I get a little water through a couple of cracks in the floor if we get heavy heavy rain.

    No issues what so ever.
  5. I agree, Pergo use to say don’t tape the seams over plywood. Me ideally everyone should be monitoring humidity levels throughout the home and keep it less than 55%. Currently I’m in the 60&70 % range due to delay in A/C installation unexpected cutting of air handler fitment on a Friday with crew having plans for weekend. Anyway those levels of humidity are wreaking havoc on my allergies, if I didn’t replace all the carpet I’d really be pissed and blame it on that. Mostly everything is new, so I surmise it’s in the air windows open whole house fan etc.

    Point being if you keep humidity level under 55%, moisture should be pulled out of the air and your entire environment to prevent moisture to go into wood,furniture,drywall,everything to cause any damage and keep air healthy. A Merv 11 filter helps as well if air flow isn’t impeded for the unit and changed/maintained.

    Just trying to say, it’s all about the big picture.

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