Advice needed on insulating and reinforcing shed please!

[and1c]

ok chaps. I need some input from you on how you would go about insulating 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 chaps

Thanks

 

[Deluks]

Get a load more treated 3x2 or cls studding and make a complete stud wall on all sides, attached the the current uprights. Go for, at max, 600mm spacings, and do the same for the roof support, making sure the new rafters are sitting on top of the new uprights. Put noggins in walls and triangulate the apes with some collar ties. Vapour barrier not really needed if using kingspan, but I'd still go with a full poly covering on top of the insulation before affixing the ply. It saves farting about with taping all the joints. (You'll still have to tape the poly seams though, so use large sheets of poly to save alternative farting about)

 

[and1c]

Get a load more treated 3x2 or cls studding and make a complete stud wall on all sides, attached the the current uprights. Go for, at max, 600mm spacings, and do the same for the roof support, making sure the new rafters are sitting on top of the new uprights. Put noggins in walls and triangulate the apes with some collar ties. Vapour barrier not really needed if using kingspan, but I'd still go with a full poly covering on top of the insulation before affixing the ply. It saves farting about with taping all the joints. (You'll still have to tape the poly seams though, so use large sheets of poly to save alternative farting about)

Thanks Deluks

Some good ideas in there.
Is it worth me putting a vent at each end to vent the new 'cavity' or is it not worth it do you think? considering there is airflow at present ..

Collar ties sound good but they will have to be very shallow to mean that i dont whack my head on them (its only 7ft apex iirc) is it still worth putting a few in?

Also, re the newly formed cavity, will do the poly covering as you suggest.
I think there is going to be a lot of farting about for this anyway not to mention the most expensive waltons shed in the North of England so where I can minimise on tedious jobs I will for sure. thanks

addition// I was thinking adding 3x2 rafters is going to be too much for the current timber support 'bar'... Any ideas that dont involved removing it as the roof halves are currently screwed into it at the apex meaning I would need to remove all felt etc!

 

[JohnD]

Is it worth me putting a vent at each end !

I think there is going to be a lot of farting

best go with the vents then

 

[Deluks]

Farting aside, yes, you will need to vent, not into the cavity, but into the shed itself, to let out any moisture which may accumalate, accumulate, accu......erm, build up.

Ties at the top can be up against the ridge beam, you could even cut into them an inch so that the ridge beam 'slots in' to them. They won't pull the roof down as they will be sitting on the uprights won't they

 

[and1c]

Farting aside, yes, you will need to vent, not into the cavity, but into the shed itself, to let out any moisture which may accumalate, accumulate, accu......erm, build up.

Ties at the top can be up against the ridge beam, you could even cut into them an inch so that the ridge beam 'slots in' to them. They won't pull the roof down as they will be sitting on the uprights won't they

Ahh.
Gotchya ....
Thanks Deluks