Internal wall insulation. Best way to deal with this?

[whatsthenews]

Building Inspector wants 25 mm insulation on the door reveals which are in a now insulated cavity wall.
The door was refitted when we had the kitchen (other side of the doorway) done, removed ugly step over concrete step and made the door frame flush with the kitchen wall.

The door lining is 35 mm and we have 37.5 mm insulated plasterboard (25mm celo plus 12.5 mm pb) which isn't foil backed.
We were thinking of fixing minimal number of ? 2x1 battens to the brickwork and fixing the insulated plasterboard to those, but this will leave the unfinished edge flush or slightly proud of the door lining, and not sure how we would finish the edge?
If we bought some foil backed insulated plasterboard could we dot and dab it to the reveals?
Thanks for any advice

 

[dontbelieveawordofit]

technically no but you could bond it with gripfill or similar to keep the depth down and put it some screws in after its set.

 

[^woody^]

You need to screw a 3 or 4x2 timber up the reveal first and fix to that.

 

[whatsthenews]

You need to screw a 3 or 4x2 timber up the reveal first and fix to that.

Thanks woody. Hadn't thought about using a larger timber .That's what we've done elsewhere on single brick walls. 3 x 2's with 50 mm insulation between and there'll also be 25 mm insulated pb over.
So where on the reveal would you advise fixing the 3 x 2? To the right of the doorway we only have about 250 mm of wall before we hit the frame of the door into the garage and we need to get some insulated pb on here too, so maybe timber on the corner so we can use it for both?
At the moment the door to the garage opens into the utility room, but we'll be fitting a new fire/smoke frame and door and changing it so it opens into the garage.