I am planning a loft conversion beneath a typical 20/30’s pitched roof of tiles on battens supported by 100 X 50mm rafters.
The work will involve the stripping and replacement of existing roofing tiles and battens.
I would like to combine a thin multifoil insulating layer (for thermal insulation) with 100m dense mineral wool for (accoustic insulation).
I also wish to line the underside of the sloping soffit with a plasterboard finish
Can you recommend an arrangement of such insulation and moisture permeable membranes and plasterboard that will:
maintain the existing roof line
maximise the use of mineral wool between the rafters
minimise the depth of insulation below the underside of the rafters
avoid condensation/coldbridging problems