Hi.
I need to redo some of the tiling on the bay window of our 1930s semi, and while I was at thought I'd try and improve the thermal efficiency. The bay itself is brick rather than timber, so no possibility of fillig with insulation. I was thinking of once the tiles and battens were off, putting some thin insulation such as Tri Iso against the wall before battening and tiling. Do I need a gap between the insulation and the wall (I was hoping to minimise the amount by which the tiles pushed away from the wall)? Should I have membrane anywhere as on a roof? Any thoughts or alternatives much appreciated.

Thanks
Ian

I've looked through the forums and they all seem to refer to bays constructed as a stud wall, whereas my bay is brickwork with no studs to insulate between!

The bay is single skin brick, rendered and plastered on the inside and battened directly to the brickwork with no felt on the outside, supported by (now) steel supports within the bay window below. The walls on the rest of the house are solid brick, although an extension to current regs surrounds much of it. As I need to address the tiling on the bay and the porch it seemed obvious to redo it with some insulation, although I haven't got a lot of space to play with.

Sheet insulation may be too thick, but if I can get some thin enough, should there be any form of underlay / membrane between that and the wall or between that and the tiles.

Thanks.