Underlay/DPM for laminate floor

Discussion in 'Other Trades Talk' started by Puffer, Apr 21, 2006.

  1. Puffer

    Puffer Member

    My question concerns laminate flooring in a ground floor or basement living room, which has wooden planked floor in good condition with adequate underfloor ventilation. Is it necessary or desirable to have a damp proof membrane in this situation, either combined with underlay or underneath it?

    My present intention is to use 7mm green 'felt' boards straight to floor with no DPM, but I have seen suggestions that GF does require DPM, whether floor is concrete or wood. Surely, if underfloor ventilation is good, rising damp is unlikely to be a problem requiring any barrier?
  2. audi-evo

    audi-evo Active Member

    We have fitted laminate flooring for a good few years now and up until last year just used pe foam on timber subfloors.
    It seems lately though that more and more laminate manufactureres are insisting on dpm underlays on all gf installations.
    That said you can get combi underlays for less money than green boards.
    I am not a fan of fibre boards, they tend to make some laminates a bit creaky (especially q-step)
    For jobs where people don't want to overspend i use a product called whisper plus, it is a pe foam with a foil dpm built in and seems to do the job quite well (£2m2)
  3. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    No DPM needed, but a good idea to lay some kind of soft underlay first(helps to even out any minor lumps or bumps in the floorboards).

    Apart from the possibility of rising damp, the DPM is recommended on all solid floors mainly because of the lack of airflow and the differing temperatures of the concrete and the wood/plastic/vinyl etc (laminate).

    Mr. HandyAndy - really
  4. audi-evo

    audi-evo Active Member

    DPM is now required on all ground floor installations with many manufactureres regardless of the subfloor constuction.
    Quick-step will be insisting on their combilay on all groundfloor installations and unisound underlay on other installations.
  5. cheltonian

    cheltonian New Member

    Topps tiles do a product called Duralay, underlay and DPM in one
  6. audi-evo

    audi-evo Active Member

    yep it is made by duralay called timbermate XL, good product.
  7. Puffer

    Puffer Member

    Thanks for your comments. I have used the green felt underlay before (but not on any GF job) and found it good; it is resilient enough to cope with small irregularities and firmer than foam, whilst the cost (about £2m/sq m) is reasonable.

    Why is it that some manufacturers are now 'insisting' on a DPM with a well-ventilated wooden floor? What has changed - is there truly a risk of damage to the laminate from damp?

    Can someone say what the trade price is at Topps is for the Duralay product?
  8. audi-evo

    audi-evo Active Member

    timbermate xl is about £2.30m2 trade.
    do i think dpm is needed on gf installations with wood floors?
    nope, i think it is a load of 80llox!
    one rep told me it is because the airflow below could be very damp as it comes from outside (yeah right!)
    I can't be bothered to argue as the price difference is negligable so i just use dpm.
  9. Puffer

    Puffer Member

    Thanks, audi-evo. I now understand the manufacturer of the intended laminate only specifies a DPM on concrete floors, so I’ll probably stick with the green felt on my wooden one. But I’ll have a look at the Duralay first.

    I agree that insisting on a DPM on a wooden floor is a load of 80llox. The same reasoning would have me lifting all the floorboards and putting the DPM underneath them, just in case a puff of damp air from the wicked world outside should contact them – shock, horror. Come to think of it, I’d better wrap all the joists in polythene too.
  10. audi-evo

    audi-evo Active Member

    Don't get me wrong i think both the timbermate xl and the tredaire boardwalk are very good products and much better than green boards.
    I use them on timber subfloors if the customer wants a bit better than standard pe foam.
    They do keep the room warmer and keep the noise down and take up some minor imperfections in the subfloor.
    The biggest problem i have found with fibreboards is that some (not all) of them are very soft and allow the laminate to flex on them making for a very creaky floor.

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