I’m after some advice concerning insulation in a pitched roof loft conversion I’m currently planning to start in my 1950’s semi, if anyone can help please. This is to be an occasional room without BC which will be used as an office / chill out room, with a sofa bed for if we have anyone stay over. I believe Building regs would require 170mm of PIR board be used for the roof, but this isn’t practical due to the restricted head room it will present once the floor joists have been upgraded to 6 x 2’s. Currently the centre of the room measures 2400mm. The rafters are 80mm deep, so I was planning on adding 50mm batons, placing 80mm Celotex between (leaving a 50mm air gap below the roof tiles) & then adding a further 30mm below. Will 110mm be enough to keep the temperature stable in there?
Being a quite competent DIYer, I’m planning on doing the majority of the work myself & keeping as close to BC as possible for safety purposes, with a couple of top hung Velux escape windows, linked fire alarms, approved stairs etc. I’d prefer to work within the regs, but I believe I wouldn’t get approval with the reduced insulation & the construction of the new floor? The purlins are 12 x 6 steels, so I was planning on running 4 x 2’s below them & across the top of the original 3 x 2 floor joists – 2 x 3m long on each side, recessed into the wall & joined above a load bearing wall in both positions. Was then going to bolt 6off 3 x 2’s onto the steels & hang down & bolt to the new 4 x 2’s for extra support. 6 x 2’s joists would then be hung from these, which would drop 2” down alongside the original joists leaving 1” space above the plasterboard. The width between the steels is approx. 3.6m & again, there is a load bearing wall along the centre, so the new 6 x 2’s would be supported at either end & packed up 1” onto the wall below the centre. I’m not going to upgrade the joists under the eaves at either side, as this will be used for storage only & will be separated off. Not planning on moving for the next 20 years or so, so the improvement is not for financial reasons - just more space
Hopefully you can understand my ramblings & offer some advice on the insulation & whether the floor construction would be acceptable to BC or not.
Thanks in advance.
Being a quite competent DIYer, I’m planning on doing the majority of the work myself & keeping as close to BC as possible for safety purposes, with a couple of top hung Velux escape windows, linked fire alarms, approved stairs etc. I’d prefer to work within the regs, but I believe I wouldn’t get approval with the reduced insulation & the construction of the new floor? The purlins are 12 x 6 steels, so I was planning on running 4 x 2’s below them & across the top of the original 3 x 2 floor joists – 2 x 3m long on each side, recessed into the wall & joined above a load bearing wall in both positions. Was then going to bolt 6off 3 x 2’s onto the steels & hang down & bolt to the new 4 x 2’s for extra support. 6 x 2’s joists would then be hung from these, which would drop 2” down alongside the original joists leaving 1” space above the plasterboard. The width between the steels is approx. 3.6m & again, there is a load bearing wall along the centre, so the new 6 x 2’s would be supported at either end & packed up 1” onto the wall below the centre. I’m not going to upgrade the joists under the eaves at either side, as this will be used for storage only & will be separated off. Not planning on moving for the next 20 years or so, so the improvement is not for financial reasons - just more space
Hopefully you can understand my ramblings & offer some advice on the insulation & whether the floor construction would be acceptable to BC or not.
Thanks in advance.