I'm doing a wet room for a nice customer who has had bought solid wood 18mm t&g and got the builders to fit it on a newish (1 month) concrete floor of an extension. They have used a what looks like sticky backed black film foam underneath. Will this be an adequate dpm or could there be problems?
sounds like they have used a product called Elastilon. Well the subfloor needs to be below 75% RH and then you should be laying a Vapiour barrier sheet also. (plastic sheet) Will it go wrong? If its a solid then i would guess that it will be showing signs of cupping in a few weeks time. If its a Engineered product they may be lucky as the Elastilon will help protect it. BUT only if they are lucky. [h=1][FONT=Arial, Helvetica, sans-serif][/FONT][/h].
It is if you're fully bonding to floor, using the crappy underlay a vapour barrier helps to bring it above 65%
for all wooden floors that are to be bonded it should be below 65%. The only way to get it this low is to install a surface DPM. If a engineered floating or even a solid floating on that underlay system it only has to be below 75%rh as you are installing a vaporous barrier.
also sounds like concrete is too new to fit on, minimum 30 days IF surface dpm being used otherwise at least 6 months depending on thickness, warmth of room etc...
And me LOL I think he is doing a wet room i guess with vinyl / tile and while he was working their a builder was fitting a wooden floor !
