How to glue T&G boards the correct way

There seems to be some strange advice around on how to glue T&G boards when using the 'floating installation' method.

Recently we have seen how wrongly applying the PVAC wood glue can cause problems - in the short and long run - where the adhesive was applied on the underlayment in front of the already installed row of boards with the idea that installing the next row would 'scoop' up enough glue to bond the boards together.

A) it doesn't and some parts of the T&G will not have enough adhesive, creating a 'weak' link
B) residue glue will be left on the underlayment, bonding part of the boards to the underlayment which can cause obstruction when the wood expands or shrinks

Another 'bright' idea is to apply drops of adhesive instead of a whole length. Again, this will cause many weak links in the construction of your floor.
With the floating method all T&G's have to be glued completely, no two ways about it, no 'saving' money in the short run (and really, bottles of PVAC wood glue aren't that expensive, compared with the costs/time of having to re-install the floor and probably  replacing many damaged boards where the T&G's have broken off because of this 'drip and drop' method).

So, what is the best method?
A PVAC wood glue bottle comes with an 'adjustable' nozzle. Depending on the size of the groove (narrow, medium or wide) you select where to cut off the nozzle. Remember: you can always go 'bigger', you can never 'knit' it back on.

Hold the board you're about to install in your hand and apply the adhesive in the bottom part of the groove, the whole length of the groove (you'll find your own 'best practise', we normally start at the lowest end of the groove, working our way up). Do the same with the short end groove.
When installing the glued board the sliding movement will spread the adhesive 'around' the Tongue of the boards of the row already installed. This is especially important with Wood-Engineered flooring where the Tongue is made of cross-layered wood (pine) which has a more open structure. Not enough adhesive on this open structure could create a weak link.
Any seepage out of the adhesive on the top of the board should be removed with a damp cloth straight away.

As with more installation methods: keep it simple and keep it clean for the best results.

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Comments

[Desmac]

I've laid a solid wood floor on Elastilon (strong). The Elastilon guide states that only the end of each plank should be glued. this is at odds with you advice. can you clarify please?

[Karin H.]

Hi Desmac

Elastilon is a self-adhesive underlayment and the product instruction should be followed.

On all other normal underlayments all the T&G's should be glued indeed.

Hope this helps
Wood You Like Ltd

[Jeffrey Duncan]

Had 5/8" floating engineered maple installed. Instructions say to use T&G glue, but I found out it was NOT used during the installation. It has now been about 5 months and the laminate layer is cupping and un-adhering to the lower portion of the plank on some boards. Is this just defective flooring or could it be a result of the glue not being used.
Thanks!

[Karin H.]

Hi Jeffrey

Delaminating is due to failing bonding between toplayer and backing and when this happens it is normally covered in the guarantee of the product.
Has nothing to do with not glueing the T&G's together.

You should contact the company your bought the product from and inform them of the problem. They must send someone out to check the problem.

Hope this helps

At 06:34 27/02/2009, you wrote:

[Prof Beton]

I've laid a solid wood floor on strong. The Elastilon guide states that only the end of each plank should be glued. this is at odds with you advice. can you clarify please?

[Karin H.]

Hi there

I think you are confusing two things here: installing floating (which needs all the T&G's glued correctly) and installing using the self-adhesive mat from Elastilon which bond the back of the whole board to the mat.

If you use the Elastilon mat, follow their instructions, they are there for a reason

Kind Regards
Wood You Like Ltd
Karin Hermans

[Matt D]

Hi I'm planning on laying mixed width oak boards ranging from 8-12" wide, and would like to know if this approach is suitable for wide boards? I'm laying onto a tiled floor (ceramic) so ideally would want to lay a DPM and Underlay then glue the T&G. I've heard some suggestions that wide boards should be glued or nailed, but would prefer floating it if possible? TheArea is about 8m x 4m aprox.

Thanks

Matt

[Karin H.]

Hi Matt

Those are very wide boards indeed! 200 - 300mm in solid is not really recommended, we normally advice is stay below the 160mm wide (6") to avoid problems.
For wider boards we would use wood-engineered boards.

The installation method is not really the issue, wood works no matter which method you use. I would not recommend using the floating method here, but your tiled floor does not allow fully bonding either. Have you considered Elastilon self-adhesive underlayment?

All in all, if possible I would recommend switching to wood-engineered boards if your heart is set on wide boards.

Hope this helps
Wood You Like Ltd

[Matt D]

Thanks Karin,

The saw mill has already started preping the order now, so going to have to make do with the width. I didn't really want the engineered boards, as they tend to be short boards with a vaneer of real wood on it. The company I've ordered from offers boards which are very long (2m plus), which appealed to me from a cosmetic point. The mill assures me that their wood is as stable as most slimmer boards, so I hope it doesn't bite me on the arse down the road!

thanks for your advice. I had looked at the sticky underlay before I stumbled across your site.