warm deck - built up correctly?

[damouse]

Hi all

Should I be worried? our flat roof - warm deck has been built up as follows by our builders and I'm not sure all is as it should be.

From the top of the roof down:

1. felting layer
2. foil backed PIR insulation board (recticel)
3. plywood
4. firings
5. roof joists
6. plasterboard ceiling

My questions are:

1) we have recticel foil backed PIR board - does this include the vapour barrier or is an additional vapour barrier required below the foam board? I've looked at the website and believe the foil acts as a vapour barrier.

2) we then also have 60mm foil backed insulation board fitted BELOW the plywood deck in the flat roof area - there is a cavity below this and then we have the ceiling plasterboard.
Is this going to be a problem in terms of condensation or anything else for that matter or am I over worrying here?

Thanks for any advice !

 

[freddiemercurystwin]

You need a polythene vapour barrier in between the insulation and the plywood deck. Fit foil backed plasterboards, only about an extra £2 per board.