Hi all,

I moved into a 1930s detached Bungalow a year ago.

Anyway, the previous owners done a loft conversion in this bungalow which has access via a small door. When I went through this door I can see alot of foil bubble wrap style insulation which im not familiar with. Behind this wrap is the stud work with normal loft style insulation (a good few inches thick) between the studs then obviously I can feel the plasterboard.

The problem I have is that the foil is sweating, I mean there is excessive water between the foil. There are water stains on the loft boards too. Anyone dealt with this foil stuff before? should it be before the other style insulation?

Reflective foil should only be used behind radiators or under a roof.
It must not be used above a ceiling!
The water vapour you and your family produce goes straight through the ceilings, through the fibreglass and should escape into the sky.
This is because plaster is transparent to water vapour as is fibreglass (which is a rubbish insulator) wet fibreglass is 4000 times better at conducting heat than dry air. It costs you more to keep if it is wet.
The best insulations are based on closed air bubbles, use polystyrene, it continues to work even when wet, even when there is a strong wind blowing.