underlay and dpm

[gas01]

Does anyone think I will have a problem laying an underlay which has a damp proof membrain on top of a damp proof membrain ?

I already have purchased my underlay which has a thin damp proof membrains, but i want an additional layer of damp proof membraine, just to be on the safe side.

G

 

[WoodYouLike]

Depends on what you're laying it on to: concrete or sheet materials/original floorboards?
The combi products that include a DPM are (normally) good on its own, no need for extra DPM. That is is you're installing it on concrete/screed floors. NO DPM on sheet material underfloor or existing floorboards.

 

[gas01]

Its going on concrete, I dont want to trust B&Q combi that i purchased, so i thought coz i have had a small damp patch before - hopefully cleared up now - I would put a damp proof membraine over the concreate base before the combi.

I didn't want there to be any issues like the two damp proof membraines sweating or anything.

Thanks

 

[WoodYouLike]

I didn't want there to be any issues like the two damp proof membraines sweating or anything.

Thanks

That could happen. Best bet then, if you can't find another better combi product is to use a separate DPM (B&Q has large sheets of proper DPM) and separate foam underlayment (also available on a roll, 2 - 3 mm thickness)