Hi, I have a plan and I wonder what people think of it?
My flat has an attic bedroom (original to when it was built 100 years ago).
It has plasterboarded eaves and ceiling with no insulation. This board is probably <20 years old and in good condition but for some reason the builder did not insulate it as they probably should.
A quote from a builder was £3000 to take down all the plasterbaord and insulate. This is too much for me, I have budget of £800.... :(

My plan:
DIY the job like this - buy insulated plasterboard and apply this to the underneath of the existing ceiling - how best to do this though??? I was thinking of: Kingspan Kooltherm K18 Insulated Plasterboard 12.5mm Facing 2400mm x 1200mm x 25mm and screw or nail it on... or does it need battons and a space between it and the old plasterboard???

What do you think? This isn't to rent out or to sell on, it's just to make my winter slightly less cold. I can probably squeeze behind the eaves and put something in there but bringing the ceiling down is a bit scary though I am a generally competent DIYer.

I will not take offense at the experts who think I'm mad, but please remember I am on a tight budget and really want to improve this situation on a budget of £800.

I would think for £800 you could remove the plasterboard, fit celetex insulation in between the joists / rafters etc. fit new plasterboard and get a plasterer to give it a skim coat.

Im only guessing as I dont know the size / complexity / access etc

Dont forget to allow for removing the waste, if you need a skip thats £250 or more.

Well I would have thought so too, but apparently not!

Does anyone know if adding insulated plasterboard to the existing ceiling is a good idea?

thanks

Before you spend £800, just confirm some facts, the building is 100yrs and the existing board is circa 20yrs:- if there is no water staining or mould we are assuming the roofing is sound and has a membrane (felt). Thermal Insulation of all types relies on static air spaces, be it between double glazing or inside foam or wool etc by adding a layer of thermal plasterboard you will gain some thermal efficiency, if you attach it directly to the existing board it will be more rigid; if you pack it with spacers leaving an air gap, it will be more effective thermally but might be less rigid. Plasterboard is stored one on top of other so I cannot see that there will be a reaction (wicking) in either method.
Others might know better or disagree.