Evening … single garage with a pitch roof against the side of the house, roof is currently just bare joists with some kind of lining then the roof tiles.
From the outside with the lights on inside you can see small gaps between the brickwork and fascia boards and also around the top of the roller door.
Not sure what the best way to insulate it is, was thinking of using some rockwool / loft insulation stuff that comes in a roll and stuff that into the edges where the roof meets the brickwork and around the rooler door, then use some Celotex type boards to go between the joists.
Also planning on boarding it over once its insulated, plaster board & get it skimmed or maybe just OSB board ??

Any info, much appreciated

Condensation. You need to get a vapour barrier on the warm side of the insulation to make sure you’re not creating a warm wet roof. Personally, because condensation is hard to predict, I’d want a vapour barrier on both sides of the insulation just to be sure.

you’ll need to think a bit about condensation and ventillation, but mainly the former.

Theres two schools of roof the warm roof and the cold roof.

If you isulate between the joists and take the plasterboard/ OSB down to the walls, with the current soffit ventilation you’ll get condensation in the void and that usually spells bad news.

I think OSB and kingspan is the right approach but iirc you’ll need to make sure you fill the underside of the joists totally and then you might need some kind osb breather membrane before your OSB

I’ve got 1/2 a roll of Tyvek wrap from my shed build, if that’d be any use?
So … put some celotex type stuff between the joists then use the Tyvek wrap to go between that and whatever board I use?
Worth stuffing the edges with the soft / insulation stuff?

Cheers

Hi there, looks to me like you’ve got a modern breathable waterproof membrane there already, so fill between the rafters with cellotex making sure you leave about 25mm gap between cellotex and membrane leave the gaps you can see from outside as these will create a flow of air and prevent condensation, then just plasterboard inside with a foil backed board and the plaster skim will take care of any draughts. 😀

Just recently moved in to the house this summer, the garage had a new roof about 3 year ago.