wall insulation

[bazil 1]

I have just stripped my shower room out and found that the external wall is just a single block thickness with a 50mm gap then a timber frame which had the plaster board fixed to it,no insulation at all.What is the best option for insulating the room?
Baz

 

[Deluks]

rip out the plasterboard, cut and place rigid foam slabs the full depth of the studwork, leaving the 50mm cavity clear, then vapour barrier (or use foil backed pb) and plasterboard over.

 

[bazil 1]

cheers deluks, just what i wanted to here