Warm Flat Roof Construction

21 Sep 2016
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United Kingdom
I've searched the internet quite a bit and have a few questions about the detail of the roof. I've also looked at Steve Roofer on youtube, which is an excellent resource.

So from my research I'm going to make up the deck with 18mm OSB, VCL, 120mm PIR insulation, 9mm OSB, wateproof layer. I'm not decided on the waterproofing yet but EPDM seems to be cost effective, any glaring issues with it?

Any recommendations on the VCL? I've seen some expensive stuff like Alutrix or Iko, are they necessary?

Did I understand correctly that 100mm fixing spacings are required? Thats a lot of screws/nails.

Ive seen tissue faced insulation and its more expensive than the foil faced option, will that be ok to use?

Is there a preference for mechanical or adhesive for fixing the seperate layers?

At the edges of the roof should I add a timber border to stop the side of the insulation getting crushed and also to allow for fixing of the fascia or will that compromise the warm deck?

Any help is much appreciated.
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