I have no cavity walls and in winter am currently freezing. I know of an external insulation which is polystyrene tiles which are then rendered. I can't however find any company that does this, does anyone know of such a thing or company in the UK?
Sorry posting a reply so I will get notified if you get answer as my daughter has same problem we had thought of using the special insulating plaster boards on inside of walls. Polystyrene ceiling tiles were popular but because of fire problems were withdrawn and also if it gets into contact with PVC it makes PVC go hard and brittle so may be no longer allowed?
Take a look at the Damp projects. The cvompany presenting these projects (PRS) give a free telephone service and there is absolutely no obligation-we know this guy well- to buy anything. They will be able to give you advice on insulation methods which will not lead to further condensation or damp problems.
Fairly recently some of the local authorities renovated and upgraded the old prefab council housing stock - part of the refirb was attaching the sheet insulation to the outside of the building and then rendering and pebble dashing over the top. So the method is available in the UK, it maybe worth asking your local authority for advice?
regarding insulation for old properties with no cavity, forget polystyrene tiles. I have just gone through 1st winter after having lined all upstairs walls (outer only) with thermal wallboard. Wifey used to hate our bedroom and the kids nicknamed it "the fridge"as it has three external walls and was constantly bitter cold. Now, its lovely and warm and heating bills come right down. Available from builders merchants, its not expensive as its plasterboard with polystyrene slab bonded to it. Passes all building regs for flame spread as obviously poly is covered by plasterboard. available in 3 thicknesses.
You dont loose much internal space as u only need to do external walls, and after decoration u would'nt know its there. Really pleased with it. My lovely old victorian house is now cozy and cheap to heat.
As Piccaso says, dry lining worked really well for me.)