www.ultimatehandyman.co.uk

Hello, I'm renovating a house with a very small utility room/porch that has a single skin wall. It's cold and damp! For lots of reasons we can't do much to change the structure or add a second round of bricks (E. G very small, the fuse box is on the wall and meters!)
we've taken tho old crumbling plaster off the walls and now trying to find the best way to move forward to get it plastered.
I've had advice to use strips of damp proof tape, screw treated batons to it and then insulated plasterboard to the batons.
I've also had advice to use vapour membrane on the walls, and then treated batons with traditional insulation and plasterboard.
Which would be best? I've added attachments with photos of both methods. Many thanks in advance

Where is the damp coming from: no DPM ground up ? Roof or guttering down? or is there a form of heat escape from the main building causing condensation?

The roof and guttering has been re done.
The walls feel are cold and damp, so I'm not sure where it's coming from - it may be just because it's a single skin wall? It's not from the ground/rising because the damp patches on the previous plaster was randomly across the wall.
The house is built with fairly high foundations with a crawl space underneath. The porch has solid 1 meter depth concrete foundation to meet the height of the house. I thinks it's highly unlikely the damp is coming from below.