Engineered Wood over 2nd floor concrete slab

Discussion in 'Hardwood and Laminates Q&A' started by Malcolm, Dec 13, 2014.

  1. Malcolm

    Malcolm New Member

    I'm helping my daughter remodel her 2 Bed/2 bath 1,100 sq ft condo in San Francisco Bay Area. We'll be covering concrete that is in very good condition. The existing carpet has been removed. Being above ground level over the building garage, we hope moisture will not be an issue.
    The two bathrooms will be tiled. We have purchased Engineered Wood, 1/2"x5"xRL Maple HS Dark Green by Kylin for use in the bedrooms, dining room, living room and the kitchen.
    In this area, no cooling system is required. We have radiant heat in the ceiling (not in the floor).
    We were initially thinking of floating the floor over some underlayment. Our remodeling contractor is proposing to seal the concrete subfloor with some kind of paint and then glue the flooring it down.
    Our questions are:
    1- What is the preferred method for installing engineered wood flooring in the circumstances described above? Floating or glued?
    2- If floated, what products would you recommend for underlayment?
    3- If it is to be glued, what are some recommended products? Is it the same glue that would be used between planks?
    4- Is there any need to do the 'painted sealing' and if so, what are some recommended products?
    5- We've heard different numbers for acclimating the flooring materials to our environment. Our GC says 24 hours will be sufficient for engineered floor. Some places say 72+ hours. Is there a standard for this (ANSI?) that we can refer our contractor to?
    Looking forward to learning from the experts.
    Best regards.

    Attached Files:

  2. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    I'd be VERY surprised if ANY wood floor manufacturer or ANY adhesive manufacturer would want a coat of paint over the concrete slab prior to a glue down wood installation.

    HUGE RED FLAG!!!!!

    Your installer is supposed to be the expert.

    #1. You can glue or float over those conditions. I would prefer glue as you don't get that hollow sound as you walk across.

    #2. Underlayment would normally be specified by the manufacturer. They all have technical dept. They usually have websites with links to installation instructions. I tend to read and follow instructions unless I know better than the manufacturer's scientists. (it happens)

    #3 Bostiks Best is the one I like. It's applied to the floor with a trowel NOT between planks in the groove like you do with the carpenter's glue on a floating install.

    #4 PAINT???? That's nutz. If you're misunderstanding the "sealer" that may be applied with a paint roller-------there are such products out there. I don't subscribe to the theory that you can solve moisture problems with something that just spills out on the slab and you slosh it around with a squeegee or paint roller. I think those things are mostly a ripoff.

    #5 Again, this is a CRITICAL detail that you need to double check with the WRITTEN INSTRUCTIONS. If you can't get this kind of info from a manufacturer I suggest you cancel the job and return the material.
  3. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Why does the floor need to be sealed?
    If paint peels guess what, the floor is attached to the paint.
    Some adhesives help block moisture from traveling into the hardwood, usually from the trowel method that applies a 1/16" extra layer of adhesive while the trowel notches add extra adhesive for bonding the wood.
    Acclimation is based on living conditions and humidity. For hardwood it's 35-55% thru the life of the building, that then correlates with the moisture in the hardwood ranging from 9-12% average tested with a moisture meter specified for hardwood and species.
    These are recommendations from pro's, manufacturers, NWFA, anything else is a gamble.
    Glad you're here asking the right questions.
  4. Steve Forbo

    Steve Forbo Pro Member

    Use glue down underlayment....
    Glue down the floor to the padding.
    That's the way 95% of the engineered jobs in NYC are installed with no issues. Never had a problem, and it's quiet, unlike floating. But the floor needs to be pretty flat..
  5. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Too broad of a statement for underlayment, any particular name brands?
    How is humidity controlled to maintain recommended levels?
  6. Malcolm

    Malcolm New Member

    Thank to all who responded.
    I called Kylin floor for installation instructions but wasn't able to get much information from the person on the phone because his command of the English language was worse than mine.
    I have no idea why the floor needs to be sealed. There is no soil contact below the concrete substrate.
    My installer is planning on using RedGard Waterproofing and Crack Prevention Membrane (Model# LQWAF3) as water proofing membrane on concrete slab. According to the manufacturer, RedGard can be used as a slab-on-grade moisture vapor barrier under all types of floor coverings. I probably improperly used the term paint since this membrane will be spread with a roller.
    He will then install flooring with Roberts Model 1407-1 Engineered Wood Glue Adhesive.

    Is there a site where I can find typical installation instructions for engineered wood flooring over concrete slab?
  7. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Sounds like he remodels out of Home Depot.
    Under all types of floorcoverings you can use Redgard? Haven't heard of that, can you quote that for me from Customs website?
    Usually manufacturer of hardwood will have installation instructions on their website, not sure if you can pull NWFA instructions without being a member.
  8. Elmer Fudd

    Elmer Fudd Administwative Asst. Charter Member I Support TFP Senior Member

    Here is their website........Kylin Hardwood Floor - Hardwood Products

    No installation instructions, the only reference to installation I could find is in the warranty "must be installed by a licensed C15 contractor".
  9. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    The products make sense, waterproof to prevent any moisture vapor coming up thru the slab.
    But who is authorizing to mix a product designed for the installation of ceramic and stone with thinsets and mortars/mastics, to installing hardwood flooring.
    Something doesn't add up, Redgard (Customs) would jump all over that procedure to sell millions worth of product under hardwood.
    A call to Customs Technical dept. Should be made -Pronto!
  10. kylenelson

    kylenelson You'll find me on the floor I Support TFP Senior Member

    it sounds like he is trying to do it right
  11. Malcolm

    Malcolm New Member

    I'm very much feeling like I'm going through a 'remodel out of Home Depot'.
    I read this at their product literature:pdf: on the first page, item 3, last line under Product Description. My concern is that it is talking about its use "as a slab-on-grade moisture vapor barrier under all types of floor coverings" while our slab is no on-grade but rather above the garage and has been there for about 30 years so any initial moisture must have evaporated long ago and there is no ground contact for additional moisture.
    Most guidelines about moisture barrier while installing on concrete slab presume it is on-grade while ours is not.
    You're right in that NWFA site documentation is for members only. I'll appreciate references to any other reliable source for installation instructions. Unfortunately, the manufacturer doesn't have any on their web site and it is too late for us to cancel and return the product.
  12. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Moisture is in concrete and passes thru if it is not blocked.
    So it appears your correct, it does say other types of flooring.
    I would then confirm with Roberts that their adhesive, the one you will be using is acceptable for going over Redgard.
    I'll tell you right now NWFA techs. Want urethane adhesives under hardwood, they don't like any water in the adhesive.
    You can call NWFA on Monday, they'll patch you thru to a tech, I think one is out of Missouri time zone, I think they're in Texas.
  13. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    Odds are more than 100-1 against you needing any moisture treatment ABOVE GRADE over 30 year old concrete.

    I've never in 30+ years of full time installation of moisture sensitive floorings, adhesives and underlayments seen a moisture failure ABOVE GRADE caused by the concrete.


    Underlayment is almost always a WORTHWHILE place to invest money whether that's improving smoothness, flatness, soundproofing, insulation, bond........

    Honest and competent flooring professionals want to give you a quality job and proper underlayment is critical to that process. They have to know right from wrong and then you have to trust their advice.

    I've never done the glue down underlayment that Steve recommends but I'm fairly sure that a good way to go. I've done underlayments under floating engineered that were like what goes under laminate----sort of a cheap plastic membrane with a very thin styrofoam pad. Normally we glue engineered directly to concrete-----after some sort of moisture treatment. With very few exceptions I've always worked in commercial settings.

    I doubt the moisture stuff he's using would hurt anything. It's a very common product. I've seen it and heard of that material. It's just not something I've ever used.

    If Roberts (adhesive) is OK with that and they're not trying the charge you any EXTRA for the material and labor I wouldn't sweat that at all. Give the adhesive tech dept. a call------I think Mike advised that already but it doesn't hurt to confirm.
  14. epoxyman

    epoxyman Pro Member

    True but if it has a metal pan under it
    It can hold moisture. Or if its light weight concrete it can still pull it up from the bottom. I have seen a none condition garage or room below the condition room above and seen the slab sweating :yesss: Only seen a few do it but have seen it. I would say you should be ok. after 30 years it should be all gone by now
  15. Malcolm

    Malcolm New Member

    Thank you all for your advice. I have no problem paying for the sealant membrane if that is the right thing to do.
    I will speak to Roberts tech support in the morning with this question and try to see if NWFA tech will talk to a non-member and maybe give me a copy of their installation guidelines.
  16. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    NWFA will talk to non members, I call them now and again. They won't send you their install guide, it is quite a big binder with volumes of information. It's included in membership @ 430$ a year. Mine is outdated so I can't say their current recommendations.
    So moisture travels as we know. I'm sure humidity gets into the garage area, I guess to know for sure it won't be an issue its best to block it.
    So we don't see exact conditions, (concrete, garage area, ceiling of garage) being on site does have a lot of factors in decision making for installation.
  17. Being the amazing installer that I am :)blink: tongue firmly in cheek) I would hazard a guess that a moisture blocking adhesive would do the job...because this is 2nd floor, you could "assume" a moisture blocking adhesive (made for slab-on-grade) should be "good enough" to block the moisture moving through an above ground slab. In theory the moisture movement would be less than slab on grade. Therefore the moisture blocking adheisve should do the job and do it with room to spare!

    Of course that assumes the installer knows what to buy, where to buy it and how much to buy...and trowel size. If you have a moisture blocking adhesive working for you, the "Redguard" (I've heard of that up here in Canada) would be over kill. The adhesive will do both: block moisture and glue the wood to the slab.

    As for acclimation...I wouldn't go anything less than 3 days. Less is dangerous...more won't do any harm. Remember: acclimation means: living temperatures in a bedroom or living room...not cold/unheated space area above garage! Heated in winter, temp controlled in summer! I've just had an owner have to expain that to her installes in (no heat while installing cork and tiles)...brrrr.
  18. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    This "above-grade-second-floor-concrete"...
    do we know for sure that it isn't Gypcrete?

    Gypcrete generally does require a sealer prior to gluing anything to it as far as I know.
  19. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    Good catch. I don't have any experience or idea what SORT of concrete material this is-------Gypcrete or lightweight both might be problematic for direct glue. So there again another good reason to use the glue down underlayment-------with or without any requisite sealers/primers
  20. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Well I was still a little skeptical, sorry if I don't believe anything until I believe, so I e mailed customs, they are awesome in my book today.

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