Insulating an exterior timber wall

Hi… I am renovating a stone house in France. Correze - so reasonably cold winters, rainy spring and autumn, and warm summers.

On the whole the house has stone exterior walls 80 to 100cm think. However there is an end wall - not strictly exterior as it is between the house and the barn - that is timber stud, with terracotta blockwork on the outside and OJB inside. Very rough and ready.

The work has reached that part of the house and of course I want to insulate it. I have read about membranes and the science of insulation and it just will not go in my thick skull. I am otherwise handy! (Have built steel stud, plastered, wired, plumbed and carpented so far).

What should I do? I want to ideally insulate the exterior (in the barn) as I am already pushed for space on that room, but if I come in 100mm or so on the inside then tant pis.

The wall is not in the weather, but faces into a cold barn (which has a large open front).

I am thinking… Rigid foam panels stuck to the exterior blockwork, perhaps with battens and an OJB (or tongue-and-groove cladding) finish. It doesn’t have to be too pretty it faces into the barn. And interior, perhaps battens, rockwool (or rigid foam) and again finished with tongue-and-groove (aesthetics more important inside of course!).

And no vapor barriers because, I don’t understand them or where to put them.

If anyone is spitting their tea out in fury please pile in and tell me what a massive **** I am and how I should be doing it!

Thanks,

Drew

It has to make sense to insulate outside because it is more efficient. Maybe use rendered breathable external wall insulation so that any moisture in the wall can breathe out. Deal with any rising damp with a physical or injected dpc.

Thanks Blup!