Insulating a 1860's Reading Room (with pictures)

[Asa Mac]

I realise that this is a very specific case and I appreciate any advice that I can get. I know that the topic of internally insulating solid stone walls is a recurring one but with all the contradictory advice I was hoping that I might be able to get a consensus on the best course of action in this instance.

Internally there is an area of damp, nothing worrying as I'm presuming it's condensation rather than anything more sinister.

The area I've butchered, in the corner of the room, had a bit of bubbling on the plaster but the concrete seems sound and, as far as I can tell by poking it, dry. There is painted backing paper currently over the plaster (which in this instance is a poor choice).

The room is fairly big so we can afford to loose some, but hopefully not too much, internal space and I plan on only insulating the two external walls in the room. The loft is fully insulated and brand new double glazing is fitted. Externally rendering is not an option since we are on Dartmoor in a preserved village.

I realise that I've bombarded this post with information but I thought I'd try and keep it all together.

My initial thoughts are to take off all the paper and any dodgy bits of plaster and dot and dab on foam backed plasterboard (potentially with foil).

Any help is greatly appreciated...*braces self for ridicule*

 

[endecotp]

You need to think about humidity. It may be that a material such as wood fibre, which is vapour-permeable and can absorb and release a certain amount of moisture, would be more appropriate than a solid insulation board. Historic Scotland have some good insulation case studies for solid stone walled buildings.