Insulating Granite Barn Walls

[tren]

Still working on my barn conversion.
Roof and mezzanine done now and am about to insulate the walls.
Internal walls are made of very rough granite with loose soil around as this was an agricultural barn. They are all a bit damp as well as the pointing wasn't done until recently.

To insulate, I am hesitating between:

- 2x2 framing with 40mm PIR in between then VCL+plasterboard
- 1x2 battens against the wall (with DPM behind) and continuous 25mm PIR on top + plasterboard (or insulated plasterboard). I know some put 25mm in between the battens too for added insulation but since my walls are pretty damp am wondering if I am not best keeping a small cavity between the stone wall and the PIR.

What would you do? Any suggestions?

Thanks

 

[Kearn]

Certainly neither of the above - modern materials are not appropriate for a solid walled structure. You will make things worse.

Why are the walls damp?

Fix this, let them dry out, which could be a year to two depending on thickness and saturation.
Dry wall = insulator.
Wet wall = conductor.

I doubt you need insulation at all, but I’d you do, then a v nice thick coat of lime plaster with perlite added for a bit of warmth.

Give the guys at Eden Hotlime, or Cornish, Mike Wye a call and see what they all have to say.

 

[jsmac]

Eden Hotlime have been a great help in my ongoing quest to work out how to insulate an external wall that gets a lot of weather but not a lot of direct sun.

While not having the same insulating values as the some of the lambda values quoted by other manufacturers' insulating plasters theirs is very competitively priced - and for my purposes at least looks to be the way forward for internal plastering.