I've had conflicting information from a couple of different roofers on the layers needed for a warm deck roof to be used as a roof terrace. Ignoring the pavers and supports, I've had:
Top
EPDM membrane
18mm OSB3 top deck
110mm PIR insulation
6mm WBP ply sub deck
Joists
Bottom
Top
EPDM membrane
9mm OSB3 top deck
110mm PIR insulation
18mm OSB3 sub deck
Joists
Bottom
The obvious difference here is that one says the thinner deck needs to be on the bottom, the other says it needs to be on the top. Are both options sound, or is one preferable?
Neither mentioned that a vapor barrier was needed. I assume it still is?
If it is still needed, is there any particular reason it needs to be between the sub deck and insulation?
To reduce deflection of the deck, I was considering the use of contact adheasive to fix the PIR to deck(s) to give a single composite slab. Any thoughts on this?
Cheers,
Fubar.
Top
EPDM membrane
18mm OSB3 top deck
110mm PIR insulation
6mm WBP ply sub deck
Joists
Bottom
Top
EPDM membrane
9mm OSB3 top deck
110mm PIR insulation
18mm OSB3 sub deck
Joists
Bottom
The obvious difference here is that one says the thinner deck needs to be on the bottom, the other says it needs to be on the top. Are both options sound, or is one preferable?
Neither mentioned that a vapor barrier was needed. I assume it still is?
If it is still needed, is there any particular reason it needs to be between the sub deck and insulation?
To reduce deflection of the deck, I was considering the use of contact adheasive to fix the PIR to deck(s) to give a single composite slab. Any thoughts on this?
Cheers,
Fubar.