Internal Wall Insulation

[JBDIY]

I have just bought a timber framed house with a wooden clapboard external wall and lime plastered internal wall( the lime plaster is old and the surface needs to be done). There is currently no wall insulation.

I was thinking of putting up insulating plaster board over the lime plaster to straighten the walls and insulate the house however i am wondering if the lime plaster would be still be able to breath or otherwise be negativley affected?

I was thinking of leaving a gap between the batons and the wall but would this be sufficent?

Also what thickness of plasterboard would be sufficent?

Any help appeciated.

[noseall]

why not remove the original plaster, fix a vapour barrier, 60mm cellotex across the timber frame, then 12.5mm plaster boards and skim?

you could also fill the void with quilt type insulation too.