Anyway, ive also posted this on another forum but had naff all input so I went searching for some help elsewhere!
I am after suggestions on how you would beef up and insulate this shed please...
It is to be used as a small workshop/engine building den and as a result I need it to be pretty dry and warm would be a bonus. The base is treated 2x3s wrapped in a DPM and outside that is a wrap of quality roofing felt to protect the DPM. Its insulated with fibreglass loft insulation. The floor is a bit overkill because their will be a fair weight with an engine in there (250kg ~) 22mm chipboard (treated) and then 12mm exterior ply (treated).
The shed is only 8ft by 6 ft due to space constraints (Waltons pre bought jobbie) and resultantly I am planning on beefing the internal structure up a bit at the same time as insulating it.
My current plan bearing in mind space is limited is to use some 2 x2 around the sides running in parallel with the current 'supports' to give me a 75mm cavity space and 2x3s under the roof as there is currently no support there!
I have a few ideas about re-enforcing the current roof support bar (maybe run 3x2s down each side of it supported by a 3x2 either side of the current gable supports?)
Then use 50mm kingspan in the cavity and board over it with 10mm ply. (do I need to use a vapour barrier against the shed wall, then kingspan, then ply?) Pics show what Ive got to work with! (I know a custom shed would have been better but I havent got time at the moment and need this workspace asap!)
The base pre DPM /insulation and felt

Inside

roof

windows (OSB? is leaning on the shed outside, not part of it!)

wall

Your experience and ideas are appreciated :):
Thanks