We've just moved into a 1970's dormer bungalow style house (where there's a large gable roof with the 2nd story and a smallish loft built into the roof). Whilst laying some network cables between rooms, we've found the previous owners had blown-in insulation in the 2nd-floor walls (which are part stud wall and part roof). I imagine that is nowhere near the recommended U value. Some of this has fell down leaving uninsulated areas as well.
After lots of googling, I was thinking of taking down the plasterboard and put PIR between and under rafters. And eventually (£££) replace the old rockwool in the loft with PIR as well so we have a thick thermal blanket all around.
My questions:
1. Do I need to involve BC, or can I just get on with it myself?
2. I know I should be aiming for 150mm of PIR to meet regs, but with a 50mm air gap, plus the plasterboard finish and possibly additional battens, it's not an insignificant reduction in room space. Is there any allowance for older properties under regulations for less insulation or is it suck it up, room space and cost aren't our problem, do what you're told. I know it might cost more per year in heating if I don't have the full amount but presumably, it wasn't significant enough for the previous owners to install better insulation themselves.
After lots of googling, I was thinking of taking down the plasterboard and put PIR between and under rafters. And eventually (£££) replace the old rockwool in the loft with PIR as well so we have a thick thermal blanket all around.
My questions:
1. Do I need to involve BC, or can I just get on with it myself?
2. I know I should be aiming for 150mm of PIR to meet regs, but with a 50mm air gap, plus the plasterboard finish and possibly additional battens, it's not an insignificant reduction in room space. Is there any allowance for older properties under regulations for less insulation or is it suck it up, room space and cost aren't our problem, do what you're told. I know it might cost more per year in heating if I don't have the full amount but presumably, it wasn't significant enough for the previous owners to install better insulation themselves.