Advice on Lime Plaster please

[Melissacottage]

Hi,

I'm helping my friend clear out a 200 Yr old cottage he's going to renovated. Builder has said that he will put batons on the internal walls and then insulated board . There will be a gap allowing the walls to breathe and so there won't be a damp problem. A lot of the old lime plaster is loose.
Should we be removing all the old lime plaster before he puts the boards up or can the more solid plaster stay in place??

I'd be grateful for any advice, thanks a mil

 

[sxturbo]

Would be better removed if it's crumbled away and surface uneven.

If it's still there and all together just board straight over

 

[blup]

It makes sense to minimise contact between wall/ plaster and batten as the damp will potentially bridge there. If you're removing the plaster why not let the wall dry out and use new lime plaster to let the wall breathe. Is there a rendered outside wall typical of Irish cottages and what does the builder say about its condition?

Blup

 

[Melissacottage]

I'd love to replace the lime render on the inside but my friend is a bit OCD about straight walls so he doesn't want that. Unfortunately this isn't a restoration because he wants to, it's because he has no other choice if he wants to have somewhere to live. Very long story.....
So do we need to remove the old plaster do you think?

 

[blup]

The loose plaster, to reduce the risk of it bridging the gap between wall and the inside of the board.

AFAIK lime plaster is applied smooth and flat like any other.

Blup

 

[sxturbo]

Damp bridging can easily be solved with dpc behind the battens

 

[blup]

Treated timber and plastic shims to level, and chop out the loose plaster.

Blup

 

[lostinthelight]

Im fitting T&G wood fibre boards then lime plastered on some of my walls
https://www.lime.org.uk/products/bo...bre-insulation-boards/schneider-room-140.html