Changing garage roof design - insulation query

[CompoSimmonite]

I'm changing the flat roof on my concrete garage from flat to low apex type. New trusses will be made out of metal then covered in ply or more probably OSB then waterproof membrane and topped off with mock tile profiled steel sheet -

Question is where do I put the insulation. Don't want a lot - just enough to stop condensation so am thinking of 25mm Kingspan or similar. Do I put insulation on top of the boards, then waterproof membrane or underneath the boards (would then probably be added after roof built)

Thanks.

Paul H

 

[the snooper]

Can't you simply get the roofing panels ready insulated if so you can do away with osb and membrane

 

[gaz1]

or you could do it how i did mine

http://www.mig-welding.co.uk/forum/threads/shed-roof-change.57025/

view pics and i used 100mm normal insulation only because it was free for me

for a 11x9 shed apex roof was just short of one roll for me any bigger you would need 2 rolls of insulation

 

[mike os]

Osb, insulation, membrane roof

 

[CompoSimmonite]

Can't you simply get the roofing panels ready insulated if so you can do away with osb and membrane

I've like to do it that way but it simply works out far dearer.
Box profile insulated sheets can be bought for reasonable price but insulated tile effect I intend fitting (will be visible to passers by hence needing something that looks half decent) is a lot dearer - I suppose it's a case of "supply and demand".
Also I can get OSB / ply at trade price via brother-in-law

 

[addjunkie]

If you look on the bay of evil you can get seconds and damaged kingspan on palletss big savings

 

[mike os]

If you use foil faced boards you won't need the osb.... osb needs the same support, so unless you want an osb ceiling there is nothing to gain really

 

[Rrunnach]

Earlier this year I assisted my bro-in-law install this stuff, see link, is really good stuff. Of course, I have no idea your budget.

http://www.planwell.co.uk/roofing/insulated_roofing_brochure.pdf

 

[123hotchef]

i would use celotex boards or similar inbetween or under or above the roof joists depending on the height u have then do away with the osb or ply

 

[Wendelspanswick]

This is the route I am most probably going to go down on my barn build:

 

[gaz1]

thanks for that one wendel

id probably go buy the t bar in steel or alluminium and the silver foil tape and the insulation needed just to create that effect for the roof