Hi all,
I have a small bedroom in my house which has a ceiling which is part sloping, where the house roof is and part flat where the loft is.
The loft part is insulated but the sloping part has no insulation between the plasterboard and the loft space/rooft. Above the plasterboard are the joists, approximately a 160mm air gap and then roof planks with no gaps, on which there are tiles. The length of the sloping part is about 180 cm. I think the roof is sealed at the end, I can't tell very easily. There is a gap at the end for between the outside wall and the plaster board.
The sloping part of the rooft is perhaps 50-60% of the area of the room's ceiling and so I believe a lot of heat is lost through that part during the winter.
However to insulate without ripping out the plasterboard means sliding something down between the joists, without blocking off the vertical gap at the end.
I was thinking of somehow sliding 100mm rockwool insulation down between the joists, though not sure how, since it will need some mechanism to push it all the way without bunching up. However, this will leave only 60mm of air gap and I'm worried that because the roof is quite sealed, that ventilation of the area will change and cause a damp problem.
The other alternative I considered was sliding down 50mm to 100mm of polystyrene sheeting, but this is more expensive than the rockwool and so I wonder whether I should just pay for the heating instead.
Any suggestions?
Thanks in advance.