Insulating external wall

Hi

I'm renovating my bathroom and I'm interested in insulating two exteriors walls. The house was built 1920s and currently the walls are plaster & lath. The bathroom is on the first floor.

The bathroom is quite small and I'd rather keep the loss of internal space to a minimum.

I'm thinking that I could remove the lath & plaster from the two external walls, leaving the brick external wall exposed. I would then fix an insulated plasterboard to this wall, of at least 50mm thickness. To finish, the board would be taped and skimmed.

Am I on the right lines? Can I attach the insulating board by dot & dab method? Should I need to be thinking about leaving a gap between the external wall and the insulating boards? Do I need to use a damp proof membrane or foil covered boards?

Thanks in advance.

Daljit

Are you sure that you have lath & plaster on the external walls?

Yes you are on the right lines. Ensure to use the correct adhesive for the dabbing, and you don't need a damp membrane.

It's a bathroom; are you going to tile over it? Someone else was asking about this recently:

//www.diynot.com/diy/threads/insulated-plasterboard-for-bathroom-with-solid-walls.472074

Thanks for responses. I'd never heard of acquapanels before! Also found the link to Historic England given on a related thread v useful.

Cheers