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Vapour barrier?


Looking for advice on what type of vapour barrier to install between rockwool 140mm (fitted inside timber frame structure) and 60mm pavatex (wood fibre insulation) or if it is necessary at all?

Kit construction in Scotland is as follows:  we are using more natural materials in our build than conventional building

dashing chips

cement scratch coat

concrete blocks

50mm cavity

6 inch timber frame with 140mm rockwool in frame

? vapour barrier?

Pavaflex (wood fibre insulation)

35mm service void

12 or 15mm plasterboard 

Topic starter Posted : 04/04/2021 3:50 pm
Chris Brookman
Member Admin


Vapour control layers and vapour barriers are always installed on the warm side of the construction and ideally up against the insulation layer. In your situation, where the vapour control layer is between two layers of insulation you shouldn't use anything too vapour tight and so I'd suggest the Ampatex Sinco vapour control membrane. This will be enough to prevent condensation within the structure but also allow excess moisture to come back towards the interior of the building if required.

Posted : 07/04/2021 6:04 am

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