tiles removed render - how to re-do in fireplace?

[trixie66]

hi

i'm removing tiles from a fireplace that will have a woodburner installed into it in 3 weeks time. When removing the tiles some of the cement render has come away from inside the fireplace. Turns out is was pretty loose so I've taken off the loose render..The largest patch is about 30cm x 80cm and the depth of render missing is about 4mm. My friend says I need to re-render the wall before re-tiling.

Questions:
1) do i need to re-do the cement render or can i just use tile adhesive instead?
2) if i need to cement render should I use a lime render (i've heard this is better for fireplaces) NB: there will be ceramic tiles on top of the render so the render will be protected from the heat somewhat
3) I've just bought sharp sand (not plasterers sand)... can i use this for render or do i have to go find plasterers sand?
4) do i pva the wall before rendering?
5) do i start at the top or the bottom with rendering??

many thanks in advance

 

[trixie66]

actually it's more like 0.25m cubed.. just measured it!

 

[tictic]

4:1:1
sharp sand:cement:lime.

 

[trixie66]

thanks for replying. I tried to find some lime but the smallest bag available is 25kg!! for such a small area i don't want to buy this much lime. If i don't use lime is it a disaster?

 

[tictic]

yes will be ok without lime,the lime just helps to float the render.

 

[tictic]

make sure your ceramic tiles are "doubled fired" for were you will be fixing them.

 

[lancenotalot]

If its only 4mm deep skim it in with some powdered flexi rapid,it will dry enough to tile on it a couple hours.