I bought a roll of FloorMuffler UltraSeal underlayment (essentially, sealed high-density foam) at Home Depot for this project. The instructions are very specific about which adhesive to use: "To be used with FloorMuffler HPA adhesive only".

This is problematic for at least two reasons:

  1. It is not clear whether the installation will fail with any other type of adhesive, or they simply prefer that I buy their product. It has become fashionable, of late, to put statements in the manuals such as "this product will only function with OEM parts", some of which are outright ridiculous, e.g. use only XYZ-brand memory sticks with your XYZ digital camera, etc. Unfortunately, in this case I cannot tell whether I can ignore it or need to take it seriously.
  2. Home Depot does not sell required adhesive. Worse still, I could not find it anywhere on the internet. They also have two different products, one to glue the foam to concrete, another to glue flooring to the foam. Seriously? To aggravate the problem, the manufacturer does not specify the type of glue they require, so I cannot even attempt to guess if it can be substituted or not. And by the way, the company's customer support is not returning phone calls, so no help there.

I bought some generic brand acrylic urethane glue for engineered hardwood flooring. Should I just go ahead and use that?

Update: I glued underlayment to concrete using Roberts Engineered Wood Flooring Adhesive. The instructions say "open time up to 20 minutes" and "install hardwood while the glue is still fresh, do not allow it to skin-over". I probably gave it 10 minutes of open time before I rolled underlayment on top of freshly applied glue. There was a lot of trapped air that caused bubbles. I pierced them and pressed the air out. Next morning I was ready to install the floor, but I noticed the glue under the underlayment is still fresh. It cured around the edges, but it is completely fresh otherwise. What did I do wrong? What are my options now? I also posted this as a separate question.

  • Is the underlayment glued to the subfloor (or existing floor)? I the new flooring glued only in the joints or to the underlayment? – bib Aug 7 '13 at 17:25
  • @bib: The underlayment is glued to concrete. The flooring glued to the underlayment. It is not glued in the joints. – user443854 Aug 7 '13 at 18:41

There is no reason to glue down engineered hardwood floor to an underlayment. This is just for initial aesthetics. The glue will NEVER last (in a residential setting). The only thing the glue will do is give you fits and make your install seem tighter. Within weeks or months the glue will come loose and you will have a floating floor.

Nothing wrong with a floating floor. But the fact is you should be gluing the pieces together, not under them. The big boxes sell the generic engineered wood flooring glue. Buy that and glue your pieces together, not under them. The only time I have seen gluing to the floor to be an option is thin flooring onto concrete for commercial purposes. The only thing I would glue down in someone home is vinyl sheets/squares.

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    My engineered floor was installed by a big box store contractor. They floated the underlayment over the existing floor, glued the grooves of the tongue and groove edges, and floated the glued up engineered floor over the underlayment. They used standard Titebond II glue (polyvinyl acetate). – bib Aug 7 '13 at 18:16
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    That is exactly how I have done all of my floating floor installs down to the glue. I would be afraid of noise with the total glue down. Would like to hear from people that went this route and how it felt/sounded a year or two later. – DMoore Aug 7 '13 at 18:18
  • @DMoore: I appreciate your insight, but in this project floating the floor is not an option. I am replacing part of flood-damaged flooring. The original install was engineered flooring glued to underlayment, glued to concrete. It seems to me the only sensible thing to do is to install new flooring exactly as existing flooring was installed. Do you disagree? – user443854 Aug 7 '13 at 18:44
  • I hear what you are doing. It just doesn't seem long term viable to me. Gluing the notches will give you the best support. I don't think gluing down the whole floor hurts, I just don't see the long-term use. I would choose my glue wisely though - I think loctite makes a glue for wood to "odd" connections. – DMoore Aug 7 '13 at 18:51
  • @DMoore: To answer your question about noise/feel with total glue-down. No issues since hardwood was installed in 2006. I cannot comment on the feel, just average, nothing wrong with it. Noise is very acceptable, too. I have a family with kids living above me (condo building, they have the exact same flooring). I can occasionally hear the kids running, but the noise is muffled, not a cause of concern. Finally, I had really difficult time ripping up damaged flooring, precisely because it was glued to underlayment, and obviously the glue lasted for 7 years. I question your "NEVER". – user443854 Aug 7 '13 at 18:51

In this case it is highly unlikely that the actual brand of glue matters. Use your generic brand glue.

Honestly I'm surprised it's a glue down floor at all. Usually the laminate floors are floating - at least in my experience...

  • I am inclined to think so, too. Wanted to hear unbiased opinions of others. Thanks for sharing yours. By the way, there is a difference between laminate and engineered, google it up if you like. – user443854 Aug 7 '13 at 18:57

whoever installed it originaly didnt have a clue what they were doing. Niether do you. you NEVER glue the underlayment..it is an Acclimating product.SMH

  • you can read about double glue down installation here: floormuffler.com/… – user443854 Apr 27 '15 at 0:46
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    This adds no value to existing answers. DMoore's answer already covered what you say without insulting OP. – Doresoom Apr 27 '15 at 13:46

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