DPM as vapour Barrier

[steq184]

Am in the middle of building a sort of man cave.
The roof is going to be constructed as follows:
Metal roof, breathable membrane, 150mm Celetex, vapour barrier and 12.5 plasterboard.
My question is could I use a dpm as the vapour barrier?
Thankyou for reading and appreciate your help.

 

[freddiemercurystwin]

Yes

 

[John D v2.0]

As above, just make sure it is on the warm side. And make sure there's a ventilated void between the membrane and the metal roof. Or just don't bother with the breather membrane if it's not needed.