Lining an outbuilding

I wondered if the extra cost of breathable membrane rather than plastic sheeting would be justified to reduce the risk of rot etc.

Thank you! That's the kind of answer I'm looking for.

This kind of thing?

Make sure there's a ventilation gap between the FE and the plastic sheet. (Not saying you've missed it, just isn't clear in the description.)

I've just repaired (rebuilt) a couple of outbuildings; 2x4 frame, OSB on the outside, breather mambrane stapled (SS stpaples) to the OSB, battens (for ventilation) then feather edge boards. I'll put rockwool between the timber framework and OSB on the inside. Nearly as good as a 199-s timber frame house!

No, I missed it! Thank you.

:oD

Firstly you need to think where the water you are keeping out is going to go. Ok you are stopping it coming inside the shed but if all it does is run down behind the feather board and rot off the ends of your 4x2 you have a problem to bite you on the bum later. Might see you out before becoming an issue though?? I'd ease off the bottom couple of feather boards and re fix them splayed out a bit to give a drainage route for water to the outside.

On the inside you need a vapour barrier on the warm side of the insulation. OSB is tolerably good at this but there could be gaps etc and whilst the insulation is exposed, sheet polythene is cheap and reliable as a vapour barrier.

Mark the position of your vertical studs not only to aid fixing the OSB but it will allow you to fix french cleats to the walls to support any hanging cupboards.

Yes yes yes to white paint on the inside. it makes a huge improvement to the effectiveness of the lighting.

Surface fix electrics fitted after you have your french cleated cupboards on the wall will save frustration of trunking and conduit getting in the way of cupboard location.

Good luck Bob

I think so - but my initial comment was pretty much the sum total of my [possible] knowledge on the matter :(

Thank you! All saved, ready for the project!!