We are converting some old stables/farm buildings with 18 inch thick stone walls. We can't increase the footprint of the building and the existing walls have to be kept as solid stone walls. Can anyone suggest a way of effectively insulating the inside of the walls without stealing too much space from the rooms, which are already rather small, and while maintaining breathability?

My apologies if this has already been covered on a previous thread. Links would be welcome.

Hi Nick ,
Good to meet you the other day ,
It's a good product they've got , shame the price is what it is, I presume is just the usual quantity and scale of product cost problem.

Xicao , I presume the non breathable insulation board would not go well with the solid walls ?
cheers James

Thanks for your comments. Pavadentro looks like the answer...until you get the price. Originally I was thinking that lime hemp mortar might be the answer but a conversation with Ty Mawr Lime, who supply it, put me off. They implied I would need it to be a few feet thick to match the insulation of celotex etc.

As for conventional insulation board, it just seems a pity to plonk anything non-breathable on the inside of a lime mortar wall. Most of our damp problems around here occur where cement render has been slapped over lime mortar walls, either on the inside or on the outside.