laminate floor and DPM

27 Feb 2008
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United Kingdom
Hi guys

I have recently bought a Quick Step laminate floor for my living and dinning room (both rooms in ground floor). The laminate floor will be installed over a wooden subfloor. I’ve read in many different places including this forum that DPM is ONLY needed when laminate will be installed over a concrete subfloor.

However see below the answer I got from Quick Step to my question about the requirement to install or not DPM in my case.

Normally, on a wooden floor, we recommend to use softboard (6mm fibre boards) as an underlayment, in order to level the unevenness in the plankfloor. The ideal solution is to put, on top of the softboard, the traditional 3mm Uniclic foam underlay to absorb also the unevenness between the softboard panels. In any case, if your plankfloor is on ground floor level, a proper damp proof membrane (screen-plastic film) has to be installed to prevent moisture ingress from the subfloor or from condensation. Make sure that the UNDERSIDE of the plankfloor is sufficiently ventilated.
If the underside of the wooden floor isn’t sufficiently ventilated, than the wooden floor has to be taken up because:
You need to install a Damp Proof Membrane on top of the parquet in order to protect the laminate floor against rising moisture and/or condensation. But if there are then problems of rising moisture or condensation, the parquet underneath will start to rot or smell… If you don’t install a Damp Proof Membrane on top of the parquet, it will be the laminate floor that will be affected in case of problems with rising moisture or condensation… So on ground floor, without ventilation underneath, the parquet will have to be removed first from the concrete base, before a laminate floor can be installed without problems…
So in any case, on ground floor level, one always needs to install a DPM. If you take a COMBI underlayment, than the DPM is already integrated in the underlayment.
We hope that the information about is sufficient, however if you have further questions please do not hesitate to contact me again.
Best regards, Frederik Daneels, technical services

I would like to know your thoughts about this. My only concern is about to loose the guarantee if I don’t install the DPM although the guys from which was where I bought my laminate say that I really don’t need the DPM.

Thanks a lot
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Hang fire until 5 ish tomorrow ( unless woody posts her views on this! ) Then i will answer you question!
No real views on this. Do what the manufacturer says in its instructions - even if it sometimes sounds like 'rubbish'. If you don't you loose your guarantee.
Thanks a lot for your reply.

I know manufacturer is just trying to protect his product as it has 25 years guarantee, so they have to make sure that nothing, including raising damp will affect the laminate floor. So basically my wooden floor could get rot and fell down, but laminate will be ok Maybe good for the manufacture but not for me

My curiosity came from the fact that I have read that install DPM over wood subfloor can create problems rather than help. Is this totally true?
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We never recommend to use a dpm on a wooden sub or underfloor because there is the risk it will prevent the normally ventilation underneath it.
If however your air-bricks are blocked for some reason any restriction by using any type of underlayment could cause problems.

So main advice: always make sure there is enough ventilation.
Really appreciate your help and for taking the time to reply back to my question.

Ventilation underneath is very good and I didn’t find anything suggesting damp when I took the carpet out. I will go ahead without install the DPM because I really believe that in my particular case it’s not worthy.

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