insulating orangery soffit

[andymoods]

I have installed a steel frame orangery on the back of my house, I have just fitted an internal soffit steel framework which I will screw plaster board to and install down lighters, the soffit measures 500m x 500mm with the glass roof above this going at a diagonal there is 25mm of polycarbonate installed 25mm away from the glass roof I am now thinking of insulating the soffit and I was wondering what you guys can recommend, not sure whether to insulate the diagonal against the polycarbonate with 50mm celotex to keep it away from the down lighters or insulate the horizontal and vertical and then cut out the insulation above the down lighters. not sure how to add images to posts but here is a link to one
//media.diynot.com/199000_198598_55176_32291695_thumb.jpg

any help apreciated[/img]

 

[noseall]

Christ on a bike that's some soffit that is!

Why steel? It will be a magnet for condensation.

Fill it with fibreglass and fit shrouds to the dl's.

 

[andymoods]

I think its the easiest way to connect to ally joist on the roof, not sure though it came as part of the kit.

should I leave room for the air to circulate behind the plaster board?, I already have some celotex boards so might use that .

 

[andymoods]

if I used 100m celotex on the horizontal then added 50mm on top of this only above the sections with down lighters would this work?