Engineered wood flooring - how best to fit?

27 Aug 2014
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United Kingdom
Hello. I have some engineered tongue and groove flooring that I am going to install on a concrete floor.

I have vapour barrier and underlay and my first question is, do I just staple these down to the concrete floor?

When that's down what's the best way to secure the wood? Do I nail down the wood grooves through to the concrete or am I better off glueing to the underlay? If I glue to the underlay will it not allow movement in the flooring? Also, do you have any recommendations for which glue to use?
Thanks for your help.
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Ok first - Engineered "product" = follow the manufacturers instructions, otherwise if anything goes wrong, they will rightly or wrongly just blame the installation.

On concrete, it is usual to either glue the boards direct to the screed, or float the boards over a suitable membrane.
was about to post a similar question. Just had our enginneered floor delivered, which we planned to glue down with Bona R850 glue. However, the delivery turned up with underlay as well. Why would we want both glue and underlay? Does that make any sense or have they just sold us more stuff unnecessarily?

About to call them, but looking for a second opinion.
Underlays are used when you float the floor.

To be clear, floating means gluing the T&G boards together and just laying them over the membrane.
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Thanks, can't for the life of me think what they thought I was going to do with both the glue and the underlay then....

I will call them and send the underlay back

I'm looking to float an engineered oak veneered floor over concrete. I haven't pulled the carpet up yet but the concrete is likely to be in good condition and level. I plan to use my reciprocating saw to cut off the bottom of the skirting boards in situ to hide the expansion gap. For a 8'x17' room I thought 1/2" gap around the perimeter would be plenty, since I read somewhere that the expansion of engineered flooring is approx. 1/10th of that of solid wood, but I don't see people saying therefore that the expansion gap can be 1/10th the size. Am I right in assuming that 1/2" gap would be plenty? I haven't decided on the exact product yet so don't have manufacturer's literature to refer to, but it'd be nice to hear if my reasoning is sound
Engineered floors do tend to move half as much, though it will depend on the exact construction of the board.

The typical 10-15mm expansion gap would be sufficient.

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