Finishing around an inset woodburner

[Bob77]

Can anyone advise on the best way to finish a wall with an inset woodburner in it (a Morso stove like this)?

 

My builder and plasterer seem to be unsure of best practice here. I know we can’t use plasterboard up to the stove front but they say they can’t plaster over cement board. At the moment the wall above the fireplace is plastered (old and a bit crumbly) and then it’s bare brick around the stove itself where they’ve knocked out the fireplace and inserted a lintel. 
 

The chimney breast is almost the last remnant of the external wall of the house after it’s been knocked through. Total width only a couple of metres. 
 

I want a plain painted finish, not tile or stone or anything. 
 

Options that I can see:

 

1) Leave the old plaster at the top of the wall, remove the last bits from the brick lower down, cover with cement board or similar and skim over the join? Sounds like a recipe for cracking where new board meets old plaster. 
 

2) Remove all the old plaster from the wall back to bare brick and cover the whole lot with board? Can the board be screwed on? Dot and dab would 

 

3) Render over the whole wall with something that will stand up to heat, after closing up the gaps around the stove with board?

 

If using board, what sort of board? As far as I know backer board isn’t meant to be used as a finish and has a rough surface - are there cement boards with a smooth paintable finish?

 

The stove has a rectangular metal frame around the door. Presumably there will be some expansion here when it heats up so should there be some kind of gap left, or a flexible but heatproof filler? Maybe even some kind of metal trim that could be painted black to match the stove and cover the gap?

 

The brochures all show lovely seamless finishes but I haven’t been able to find out how to achieve it. Even the installers said they had never actually seen the end result!
 

 

Edited October 10, 2022 by Bob77