Heat resistant paintable filler needed

[sjws1888]

Hi
I'm doing up the living room and I've had it plastered including inside the fireplace which has a log burner in it. The plasterer has put fibreboard inside the fireplace and not skimmed it because he said the heat would crack the plaster. Planning to paint this board with heat proof paint.
My problem is that the board doesn't quite reach the hearth tiles i.e. there is a 10mm gap or so between the tiles and fireboard.
Can anyone recommend any type of 'filler' type material that I can use to fill this gap. Needs to be something heat resistant and paintable.
Many thanks for any help

 

[Bonni]

Lime mortar.

You normally lime render or fireboard the fireplace around a woodburner.

 

[lostinthelight]

What about a row of skirting tiles or granite upstand off the floor to cover the gap.

 

[Bonni]

Yes, Granite is a good choice. With sticking them to the wall, I believe you can use a tile adhesive for Aga areas etc. Best to ask a tile merchants for the type of suitable materials.

When I've been roped in to lime render that area, I've just rendered down to the hearth.