Fix Plasterboard to metal plate soffit

[Disk]

I am in the process of replacing rotten timber window lintels in an old house. The new Lintel per Structural Engineer will result in a galvanised steel plate as the internal soffit which will subsequently need to be plastered. I was thinking of using insulated plaster board fixed with aerosol Foam to the steel, rather than trying to screw into 6mm plate steel, and it would also provide a further thermal break.
I would appreciate any thoughts on the use of the Foam and whether you think it would work?

Thanks for any help

 

[roy c]

Dab it with Sticks like Sh#t ,Its one of the best adhesives on the market for jobs like yours...

 

[Disk]

Thanks Roy C, but I am concerned about cold bridges and condensation on the base plate. I want to create as much of a thermal break between the metal and the plasterboard as I can. The insulating plasterboard will help and I thought that the foam would help as well as sticking the plasterboard. Would the sticks like**** stuff be as good as the aerosol foam for insulation as well as adhesion?

 

[roy c]

I would think that when you have fixed the insulatedboard and it is pretty tight up to the metal lintol the polystyrene should stop any "cold spot". Just my opinion but that is the way I have stuck them up before.

 

[Disk]

Your advice and help much appreciated RoyC, I'll give it a go.