Heat resistant render

[Tobiasisno1]

Hi folks. I'm ready now to render the chimney breast and recess into which the wood burner is to be fitted. I've searched on here for the mix to use and it seems to be - for the base coat 4 sand:1 cement:1 lime and for the top coat 6:1:1. Is that right?

Going to the next stage, does anyone know if special paint is required or will ordinary emulsion cope with the heat? I realise the decorating forum is the place to ask, just thought I'd ask here while I'm here.

All replies gratefully received

Keith

 

[Richard C]

4:1:1 may be a little strong for the heat. After suffering an initial failure on my a personally fire install some 2 years ago, I used 5:1:1 mix the both coats but with the scratch coat fairly wet so not so strong; I’ve also used the same mix on a couple more stove installs since then & it’s been OK. You could use a 5:1:1 or 6:1:1 for the float coat & my initial research, some reckon an even weaker mix copes with the heat better. The other alternative is to use a pucker heat proof screed but it’s obviously more expensive (not sure how it differs either); don’t under any circumstances use Gypsum based plaster base or finish, it will fall off.

With regard to the paint; I’ve just used standard matt emulsion on the wall/breast surrounding inset stoves which get up to around 100 deg. C without any problems but the recess may get somewhat hotter; I couldn’t find any info regarding max. temp. on the Crown data sheet I pulled up.

 

[Tobiasisno1]

Thanks Richard, I'll pass this on to my plasterer. I'll probably check with the paint manufacturer re the suitability of the paint.

Keith

4:1:1 may be a little strong for the heat. After suffering an initial failure on my a personally fire install some 2 years ago, I used 5:1:1 mix the both coats but with the scratch coat fairly wet so not so strong; I’ve also used the same mix on a couple more stove installs since then & it’s been OK. You could use a 5:1:1 or 6:1:1 for the float coat & my initial research, some reckon an even weaker mix copes with the heat better. The other alternative is to use a pucker heat proof screed but it’s obviously more expensive (not sure how it differs either); don’t under any circumstances use Gypsum based plaster base or finish, it will fall off.

With regard to the paint; I’ve just used standard matt emulsion on the wall/breast surrounding inset stoves which get up to around 100 deg. C without any problems but the recess may get somewhat hotter; I couldn’t find any info regarding max. temp. on the Crown data sheet I pulled up.