KINGSPAN IN RAFTERS DO I NOW PUT IN MEMBRANE?

[Nicetoseeyoutoseeyounice]

I am in the middle of doing my loft, I have now put Kingspan in between all the rafters, before I get the plasterer to put plasterboards on and skim, do I firstly have to now put some form of membrane over the Kingspan which in turn will be between the Kingspan and the plaster boards?

 

[freddiemercurystwin]

If you used foil backed insulation you can just seal the gaps with foil tape, this will create your vapour barrier. If not foil backed insulation you can just fit foil backed plasterboard which will form your vapour barrier (it doesn't really matter that there'll be theoretical gaps at the joints). This is the cheapest/easiest way of achieving a vapour barrier.

Surprised you've not fitted a continuous layer of insulation beneath the rafters though in addition to the insulation between the rafters (or maybe you have).

 

[Nicetoseeyoutoseeyounice]

Hi and thank you for the reply. Forgive my ignorance but I don't understand when you say a continuous layer beneath the rafters, do you mean deep into the eaves, ie the bit we won't be using. Also we don't have any gaps to seal as we have managed a continuous run of Kingspan as they are huge sheets, so one long piece between the rafters, is this right?

 

[freddiemercurystwin]

Normally to achieve the required U Value a continuous layer is required beneath the rafters as well as a layer between them like this:

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• freddiemercurystwin
• 8 Jun 2010
• 20