What insulation can we fit???

[littlesos]

We have recently moved into a dormer bungalow. The dormer conversion was done in the 70's, so the insulation in the roof is pitiful. We want to increase the quality of the insulation but we're stuck as to what we can use, as the rafters are only 70mm deep. With the regulation 50mm airgap that only leaves us 20mm, without encroaching on the room-sizes.

I know we could strip the roof and put breathable membrane on so we could use th whole 70mm gap, but is there something out there that won't cost that much. We haven't got much spare money, but would like to do our bit to conserve energy (we've just had cavity wall insulation fitted).

From a quick look on the internet it looks like out only option is spray-on foam. If we leave the felt on the roof and spray onto the felt roof repairs will be easy, bit would we need to leave a 50mm airgap for this too?

Thanks

 

[JerryM]

no experience of this but gut feeling would not be to use foam.

i would go for aluminium foil (something like screwfix 76477 or 21112) or nail additional battens to enable std insulation boards (28148).

Suggest visiting your local builders merchant to see what they sell.