Insulating Solid Stone External Walls Where Plaster is Coming off of Lathe? Ask your questions and find answers on many subjects relating to plastering and dry lining

[carter62]

Just bought a detached house approx 100 years old with solid stone walls. The plaster has lost keys to lath in large areas, probably over 75% of all walls. Room runs depth of house, from front to back, and has 3 external walls, with the front and back having sloping walls (or combed ceiling?) Have easily removed the plaster on all walls with a wallpaper scraper!!! and more than a little help from gravity. The lath remains and is nailed to upright batons secured to the wall. There is also deep plaster ornate coving which I would like to save so must consider thickness of whatever I use. There is a dormer window to the front. There are no signs of damp or mould nor is there insulation. I need to make good the walls and was going to replace with plasterboard over the lath and have this skimmed with plaster but realise this will be colder than lath and plaster. Money is an issue and I have a very tight budget but am a competent DIYer. Although my skill level is OK I have not tackled this before and I am very confused about insulation. I don't want to just put insulation between the batons and board over as am concerned about causing dampness if insulation fills the gap and is in contact with stone wall. What is the best way to remedy this problem which was only discovered when I started stripping wallpaper.

[thedoctor]

use foil backed insulation slabs after removing laths. The foil will refelect cold back outside and heat inside. If the vertical studs are 100mm timbers, use 50mm insulation, if the studs are 50mm timber use 25mm insulation. There should be an air gap between the front of the insulation and the plasterboard so get the insulation pushed against the wall. Plasterboard and skim as you suggest. Good luck and do let is know how you get on. If you fancy posting some images of the job it might help others in your position as well as making the questions easier to understand.

[carter62]

Thank you so much for your reply. I was thinking that the cross section would be solid external wall, air gap, insulation then plasterboard and skim. Makes for an easier job with insulation hard to the external wall then the air gap then plasterboard. Would this be the same for the sloping walls/ceiling?

[diydoctor6]

Hi carter62,
Sorry that this might be a bit last for you, but it might help others reading this post.
There is a fully written up explanation of the options that you could use for Internal Wall Insulation here :

https://www.diydoctor.org.uk/projects/in ... gwalls.htm

Hope that this explains things more clearly.