I am looking to install floating engineered wood flooring (20mm thickness), tongue and grove system.

The boards need to be glued together.

Different manuals/guides/tutorials state that the glue should be put on top of the tongue. Other tutorials state that the glue has to be put inside the grove.

I think putting inside grove ensures that glue will go on both bottom and the top of tongue, but I am slightly worried that it might be more difficult to ensure that the glue is spread evenly.

I am also worried that the glue might "leak" on the underlay and damage the waterproof membrame once it dries.

In the same time with putting glue only on top of the tongue doesn't look like it's enough?

  • 1
    Check the manual for the product you actually use. The other manuals are only correct for the product they come with.
    – Solar Mike
    Nov 7, 2022 at 11:53
  • 2
    Yes. Only do exactly what the instructions that came with your product say. The warranty depends on it.
    – gnicko
    Nov 7, 2022 at 11:55

1 Answer 1


If the glue is put on top of the tongue it will squeeze out of the top when the boards are pushed together and you will have a mess to clean. This also assures that no glue will be bonding any of the lower groove or underside of the tongue. I cannot believe this is the preferred method of installation. Still check the instructions from the manufacturer. A little wood glue on the membrane should be inconsequential.

  • Back in the novel days of Pergo, doing what you describe in the opening sentence was standard procedure. It created a seal against water that was desirable. You make it sound like a fault, which may or may not be true.
    – isherwood
    Dec 7, 2022 at 15:21
  • It did exactly as I described, and yes you are correct it created a seal against water, and it was, as I said, a mess to clean up.
    – RMDman
    Dec 8, 2022 at 1:22
  • Thinking again about this method, makes me wonder if it is one reason that type of Pergo is obsolete.
    – RMDman
    Dec 8, 2022 at 4:16
  • It isn't. That type and that installation method are. Pergo is alive and well as a manufacturer.
    – isherwood
    Dec 8, 2022 at 13:58
  • Here in the SE USA I haven't seen glue together Pergo for sale in at least 10 years. Even their click together products are few and far between. Why would anyone use that product when there are so many others that are better at the same or lower price point. But Hey!...if someone wants to use an outdated product that is overpriced and takes longer to install go for it.
    – RMDman
    Dec 8, 2022 at 14:54

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