Insulating door reveals with tilebacker board

[bmj1]

I need to close a couple of door reveals, with fairly minimal thickness/build-up.

 

Dot + dab insulated plasterboard is going to take 40mm+ of build-up.

 

Could I use tilebacker board/wediboard (these are good for insulation) ? And then plaster skim on top ? How would I fix it to the concrete block ?

 

Thank you in advance.

[Barnboy]

I did this in a way. My reveals are deep as in the wall is thick but I didn't have much depth for insulation. I used spacetherm blanket against the stone with a marine ply box to form the inner reveal. I didn't have much room left before I'd loose sight of my window frame so I used plasterboard adhesive Gun foam to fix Jackonboard onto the marine ply which was then sealed with either diluted pva or sbr and plastered. So far so good. I started a thread on it " jackoboard on ply " someone commented they'd used the same method onto brick and it was solid.  Just make sure that you wait the recommended time for the foam to expand before fixing the board into place.