Hi,
I am renovating a victorian end terrace. I want to put insulation under the ground floor boards. There is a void with a [now] good air flow. My question is how to insulate. A foil backed board would be simple but expensive and I an unsure whether a vapour barrier between the boards and void could cause any problems. I have seen polystyrene boards without foil, these are cheaper but are they as efficient and are they breathable. The other alternative is fibreglass which would be cheap although a bit more tricky to prevent it sagging, but again is it breathable and does it matter? Any advise would be helpful.
Also the house has no loft insulation. Iam sure that this has been discussed many times before but does anyone know the recommended thickness of fibreglass or is it worth considering another product, unfortunately cost is a factor.
Thanks for any advice