I have just built myself a new shed. It’s about 4 metres long and 2.4 wide. I’m very proud of it.

I intend to use it as a play room, workshop and office. It has lights and power and a nice wood burner. It’s lovely.

BUT! it’s only a shell at the moment (E.g. a single cladded skin structure).

Is there any point in me insulating it. What do you reckon the cost will be and what should I look out for? My intention is to bash some plaster board up anyway…so there will be a 2 inch cavity. Or shall I just burn more wood.

Put Rockwool type insulation into the cavity and use plasterboard with 25mm of polystyrene bonded to it.

kingspan is loads easier to work with.

Recycled plstic bottle insulation, from B and Q, re uses waste, and doesnt itch like fibreglass does, as for the inside boarding use 12 mm mdf.or plywood, it withstands bangs better than palasterboard.

Dont forget the roof as well, and fit good quality locks to the doors and windows.

PUR Insulation, the rigid stuff is prob better, easier to work with and better insulation values. Kingspan is a brand but expensive. Cellotex is another but cheaper and does the same thing. There are others but whatever/whoever offers the best deal will suffice.

Plasterboard with insulation bonded on to the rear is VERY expensive and works out cheaper to buy seperatley if its for DIY. Use half inch plasterboard and 25mm polystyrene, tack the polystyrene to the framing and then screw through the lot with 50mm drywall screws to secure in place.

Anything like rock wool or fibre glass will sag and ‘belly’ and won’t be particularly great in a relatively short period of time.

As flatfish suggests, bonded insulation board will be far better. You generally get a better R value per given thickness. You will pay more than fibre matt type stuff though, although, it will (IMO) pay for itself during installation (hours saved).

I used rockwool but regret it. It Used a breathable membrane between the outerplanking and the insulation, then plastic sheeting then the boarding. It still gets a bit damp. I’d use kingspan if I was to do it again.

Deffo a good point on the plasterboard, it’s not hard enough for a shed by any stretch, plus it won’t stand up to any damp at all. MDF is good, ply better. Kingspan/celotex/jablite is the best stuff for insulation, but the most expensive. You could use isover fibreglass slabs, they’re cheap