Drylining ceiling?

[PalletRefurb]

Just after a bit of advice on my washhouse i'm doing up at the moment.... I've battened off the walls, visqueened them all off. Doing my ceiling now... Was just after advice in regards to this.. I'll layer the text how i've got everything...


Torch on felt (horizontally)
Torch on underlay(vertically)
Torch on underlay(horizontally)
18mm OSB sheets
Sloped timberwork (6inches down to 2 inches)
4 inches concrete roof
(all above is obviously external)
**************
3x2 battoned ceiling
75mm kingspan
12.5mm plasterboard
plaster

my question is, would you put visqueen internally on the concrete roof? or just proceed with my plan as normal?
and would you insulate externally (between concrete and OSB) perhaps with rockwool ?

 

[tomfe]

You still need a vented void above your insulation.
I'd be tempted to do a warm roof however depending on how the walls meet the roof you might have a bad thermal bridge. Or a hybrid roof :https://www.diynot.com/diy/threads/building-a-warm-flat-roof.478729/

 

[GeorgeBatesUK]

Hi does this guide answer your question? http://www.gypsumtools.com/blog/ultimate-dryiling-guide/