Battens and plasterboard on single and cavity walls, vapour control

[OldKettle]

Hi,
I have an outbuilding which I would like to line with battens and plasterboard, and add additional insulation behind the plasterboard.

One of the walls is a single brick external wall, and the rest are all cavity walls, some external and some internal.

The single brick external wall is exposed brick and all the cavity walls are plastered and painted.

I was just hoping that somebody could please give me some pointers on vapour control for the different surfaces.

I'm assuming that I don't need to add a vapour layer to the internal cavity walls, and I'm hoping that the same would apply to the external cavity walls. With the external single brick wall, I expect that some kind of vapour control layer would be needed.

Any thoughts would be much appreciated.

 

[noseall]

Structural vapour or moisture control is reserved for timber frame buildings. You may be wise however to mitigate any damp ingress via a DPM trapped behind the battens. Once you have fixed the battens and fitted the foil sandwich insulation between (and across the battens), foam all gaps then use foil tape over all the joins. Use foil back plasterboard (duplex).

Don't forget the relationship between wall and floor when mitigating damp ingress.

 

[John D v2.0]

if it's just an outbuilding and you're not having any moisture producing activities, it's less important to get the detailing on this right. Do you really need to insulate the external cavity walls? and the internal ones that separate from the house too?
we were belt and two sets of braces with the vcl when we internally insulated our shower room because it's a very humid room, basically the same setup as yours, and we taped the insulation joints, then put a poly sheet over the lot taped at the edges, then put the shower panels on top of that. For the bay window we just did a poly sheet.
Hope that helps (I'm not a builder!)