On Sat, 21 May 2005 13:03:25 GMT, Joe T wrote:

I'm about to replace a carpet (laid on concrete) with laminate flooring.

Instructions mention using an underlay with a vapour barrier. However, don't
concrete floors in houses already have a damp proof membrane incorporated?

Is the vapour barrier only required in a new house where the concrete has not
yet fully dried out? Or is there some other dampness factor I am missing?

I strongly suspect it's not necessary. I've just finished doing some,
using the combifloor with the built-in vapour barrier (and the rather
nifty arrangement for fastening the edges together). It didn't add
much to the overall cost of the project, but I did wonder - as you are
doing - that if my carpet never got soggy, mouldy or smelly, there
really is a need for it.
--
On-line canal route planner: http://www.canalplan.org.uk

(Waterways World site of the month, April 2001)

Laminate flooring - vapour barrier underlay really necessary?
 

I'm about to replace a carpet (laid on concrete) with laminate flooring.

Instructions mention using an underlay with a vapour barrier. However, don't
concrete floors in houses already have a damp proof membrane incorporated?

Is the vapour barrier only required in a new house where the concrete has not
yet fully dried out? Or is there some other dampness factor I am missing?

but I did wonder - as you are
doing - that if my carpet never got soggy, mouldy or smelly, there
really is a need for it.

Good point that. I did lay a blue plastic barrier under mine but I wonder
now if it was a waste.


Dave

Nick Atty wrote:

I did wonder - as you are
doing - that if my carpet never got soggy, mouldy or smelly, there
really is a need for it.


Your carpet is highly permeable, and allows any trapped moisture to
escape. Laminate is almost completely impermeable. Water will be trapped
under it, and absorbed by the bottom surface. This will cause swelling
and distortion. How much will depend on how good your DPM is under your
concrete.


--
Grunff

If the instruction mention DPM, use it. If any problems occur later, your warrantee will be useless.
Plus the DPM underneath the concrete has nothing to do with protecting your wooden flooring on the concrete itself. We always use DPM when installing wooden flooring on concrete/screed underfloor: a - hardly any extra costs, b - better protection against any residue moist in the concrete floor (however old)