Garden workshop construction

[Gossamer]

Morning,
Just after some advice on how to construct the walls of a garden shed / workshop.
Thinking from inside to outside:

12mm ply
Studs (75x50 treated cls) and insulation inbetween studs
Tyvek breather membrane
~20mm thick battens over membrane, screwed into studs
Featheredge secured to battens (with 20mm air gap).

Is this reasonable? I was wondering whether to ply line the outside too.

 

[big-all]

cls is 63x38[1.5x2.5"] so a bit too tight for 50mm insulation

 

[Gossamer]

cls is 63x38[1.5x2.5"] so a bit too tight for 50mm insulation

Was planning to use 50mm rockwool which is semi-rigid. I've used it in my house and it keeps its dimensions very well.

 

[big-all]

it will probably slump so fill say the bottom 25% and an inch or so gap at the top assuming 2ft noggins
70mm kingspan /celotex or other solid foam and 89mm cls would be better

 

[Gossamer]

it will probably slump so fill say the bottom 25% and an inch or so gap at the top assuming 2ft noggins
70mm kingspan /celotex or other solid foam and 89mm cls would be better

I did think about bigger studs but for a workshop I reckon 75x50 is ample, and it will be ply lined etc so strong enough I reckon.

I didn't understand your slumping comment tbh, why leave a gap at the top if it slumps?

 

[big-all]

the gap is caused by the slumping

 

[big-all]

actually scrub that rock wool is ok my brain said loft insulation lol
yes it wont slump or drop but needs a decent airspace
its not so much the strength issue its the heat retention issue

 

[Gossamer]

actually scrub that rock wool is ok my brain said loft insulation lol
yes it wont slump or drop but needs a decent airspace
its not so much the strength issue its the heat retention issue

Behind it will be plywood, and in front the membrane, which I understand is breathable and waterproof. Then a ~20mm gap to the featheredge (i.e. an airgap) so it *should* get plenty of air.

Is it normal to ply line in front of the studs? I've seen some do and some don't (well most do).

 

[big-all]

12mm ply then you can hang what you like off it
other alternatives are 11mm osb
tyvec or other breathable membranes are pretty good use a tack hammer to save ages

 

[Gossamer]

I meant in front of the studs, i.e. ply line, membrane, batten and featheredge. I am planning on not ply lining in front - membrane, batten and featheredge

 

[big-all]

inside ---ply insulation air gap breathable membrane baton cladding ---outside