Damp proof membrane on slate flagstones?

schmink

I'm laying a tongue and groove floating floor on top of slate flagstones. Before putting down the underlay do I need to lay a damp proof membrane/sheeting? As I understand it, slate is impermeable so I wasnt sure if the membrane is needed. Any help gratefully recieved!!

dampdaveski

Hi,
slate is indeed impermeable, however all the joints/ edges arn't
If you lay a wood product directly onto flags it will definately end in tears or more precisely warped floorboards etc.
I would lay a slimline cavity drainage membrane system on top of the flags, then lay your floor.
there are lots of online damproofing shops selling these products, however be warned, the mark up they put on is criminal!
For obvious reasons I can't put their website addresses on.
My advice is to shop around, if nothing else ring round your local damproofing companies, they may not charge much just for laying the membrane, they may even sell you the stuff cheaper than you can get it 'online'
hope this helps

D

schmink

Thanks Daveski

I'm not sure I understand exaclty how a drainage membrane works. Does it redirect moisture?

Taking into account cost, would a more basic damp proof membrane suffice?

Thanks

mikey72

you could look at
http://www.screwfix.com/prods/52649/Flooring/Flooring-Accessories/Foam-Underlay-with-DPM

wallbash

If the slate flagstones are in good condtion , with mininal gaps and you havent had problems with damp . I would go with the product found by mikey72 from screw fix.