DPM on internal walls

[wood10015]

Hi, I am doing some renovating and trying to do as much myself as possible. Our architect has stated on plans passed by building control, on the inside of external walls (9" brickwork c1860) line with 1000 gauge, batten out with treated timber 50x50, at 600cts an then fix 25 celotex in between. My question is is it normal to line with 1000 gauge polythene, I'm worried about the walls breathing and condensation build up. i just want to know if this is a practise normally used in buildings to keep damp out. A builder in passing said to me it should be a breathable membrane. I assume as its on the plans it's ok?

I have searched through lots of old threads but cannot find any questions on this so apologise if I am duplicating a previous question. Help an advice appreciated

Thanks

 

[Deluks]

Is the outside ground banked up against the wall? A solid niner wont let any rainwater in.

Breather membrane is the right idea but not in this situation where the timber is fixed straight to the wall and with a foam board inso.
Only 25mm celotex? Are you boarding over the studs with insulated plasterboard?

 

[wood10015]

Hi - ground is banked up against the wall but not above floor levels. Thanks for clarifying re membrane and glad this is right in this circumstance. No insulated plasterboard, just 13mm foil backed to be used.

Thanks

 

[Deluks]

So to clarify you do not need any membrane, and you should really aim for 50mm celotex as a bare minimum.