mushymanrob wrote:
hi

i have an old house..80 odd years.. the plaster is pretty caput and
theres no cavity wall. what i want to do is insulate the outer walls
as im renovating it. i figured that if i could get some insulation,
then put plasterboard over it then id have new walls and an insulated
house.

is this idea possible?

Yes.

what insulation should i use?

You can buy insulated p-board, they have polystyrene on the back of them.

how would i fix the plasterboard over the insulation? battens?

If you are going to batten each wall, then you can use fibreglass, which
would be cheaper.
Set your battens at 300mm centres upright, and 1800mm horizontally, then
when you screw the p-boards on (900 X 1800's) they will meet the battens
half way across.

Bear in mind that you will lose the skirting boards on these walls and also
any elecrical cables and fittings will need to be removed and/or replaced.