Best underlay for engineered wood

6 Feb 2013
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United Kingdom
Hi all,

Hoping one of the friendly flooring experts on here can help with my question:

We have bought some Kahrs 15mm thick engineered wood flooring to put down in our kitchen. Our sub-floor is t+g pine boards 100mm wide by 22mm thick, over 4x2 joists above a ventilated ground floor with concrete oversite. It is all quite dry under the floor. The floorboards are fairly level, but there is one area where I will do some shimming of the joists to get the whole floor within the spec from Kahrs.

We were recommended by our local flooring supplier to use a 7mm fibreboard underlay, and as a result, I have put the kitchen units in allowing for 22mm finished floor thickness (15mm boards + 7mm underlay).

Now, reading around, Kahrs seem to recommend their Tuplex (foam balls and plastic sheets) underlay, but that has a built-in DPM, which I understand is a no-no on my sub-floor type, and it also gives me a problem with the kitchen as it is thinner than I need.

The basic question is: are fibreboards a suitable underlay for my application, despite the fact that they are not Kahrs own product or specific recommendation? Can anybody recommend a high quality 7mm fibreboard I should consider using?

Also, Kahrs suggest that all sub-floor types require a DPM in the underlay, but that can’t be right, can it?


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It's my understanding that all of the above is accurate, don't use DPM over wood, fibreboards should be fine and an alternative to fibreboard would be the non-foil version of TimbermateXL (can't think of it's name right now.)

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