insulating an outbuilding - advice sought

[Tetrarch]

Hi All,

I have an outbuilding that I've built and now want to improve the inside. I appreciate that I may have done this a little back to front

These are some of the photos from the build. It's a mixture of brick wall, brick pillars, a timber "ring beam" and a noggined 4x2 roof at ~600 centres. The cladding is 28mm loglap attached directly to 50mm steel framing

Walls

I was wondering how I could effectively insulate the structure. I was thinking of using 50mm PIR (or batts) between the steel and finishing the inside with plywood. Do I need a waterproof layer to stop condensation? It's not a live-in structure, just for use as a workshop. I mainly want to stop tools going rusty

My plan is loglap - insulation - plywood but if I do need a waterproof layer, does it matter where it goes

Roof

This is slightly complicated by the fact that I have solar panels being fitted next week so this may well have to be done post...

Currently 9mm OSB with EPDM (currently loose, but going to fix down with solar rails and then finish the edges properly)

Any advice welcome

Regards

Tet

 

[freddiemercurystwin]

Ideally you would have plywood + vapour barrier + insulation (stud layer) + breathable membrane + vertical battens + horizontal battens + cladding.

 

[Tetrarch]

Ideally you would have plywood + vapour barrier + insulation (stud layer) + breathable membrane + vertical battens + horizontal battens + cladding.

Thanks for the reply. Short of taking the whole thing apart (that I could do as it was built to be demountable for the planners) what is the practical downside of?

plywood + vapour barrier + insulation (stud layer) + breathable membrane + vertical battens + horizontal battens + cladding.

The cladding is tongue and groove so gives a fair amount of structural rigidity as well (the middle picture was partial - the steel is at ~450 centres

Regards

Tet