Home DIY

On the subject of plastering, has anyone ever used some sort of heat-proof plaster before My builder made a complete balls of installing my cassette type bio-ethanol fire so I'm considering ripping it out and doing it myself. Fairly confident in the construction but the finishing may be a challenge considering I've never plastered before and this stuff says you can't sand or feather it.

Sort of bumping this, or rather changing the question - if I mount my cement board flush to the adjacent plaster, will I get away without plastering? The board looks fairly smooth from the images. Would take the trickiest part out of the equation.