How to plaster open fire chimney breast

[Plasterman101]

Hi, I'm hoping to plaster our dining room in a small victorian end terrace house. Much of the old plaster is blown so I've removed it all including lath and plaster ceiling.

I plan to plasterboard and skim ceiling, dot & dab and plasterboard walls and alcove either side of chimney breast.

Question is, how to I deal with chimney breast with open fire? British Gypsum say not to use their products and find cement based plasterboard.

Internet research points to sand, cement (scratch and top coat) with victas or ever build heat resistant plaster on top.

Any thoughts or advice would be much appreciated.

 

[JessThePlasterer]

I think you’ve answered your own question there!

when someone doesn’t know what they’re going to do with their fireplace I always s/c it. Or if the brickworks good suggest leaving the brick

welcome along!

 

[Brimstone]

There's several threads already on this. What BG mean is a pure cement board such as Hardiebacker, there are others. So much easier than the other solutions. Don't try Vitcas on sand and cement, they're different products and I don't think will work well together, go with one of the other.

If you want an open fire the best thing is to replace the fireback chair and throat etc so it has a chance of working and producing a bit of radiant heat.

 

[Tinytom]

I think your talking about the face of the chimney, not the actual builders opening?
if so just bond and skim, the heat won’t bother it too much. An open fire the majority goes straight up the chimney anyway

 

[raytheplasterer]

this is the idea of mantlepieces, they deflect the direct heat from the fire away from the wall and into the room.

 

[Plasterman101]

Thanks all, for your replies. Picture attached of the current state. I'm picking away at the old 60's(?) concrete and tile fireplace, wondering how far to go. Dont fancy whole inner fireplace refurb. Way out of my comfort zone. Revealed arch of bricks too with same height mantle piece indents cut out of wooden corner dowels.

So it's looking like I'll s&c the chimney breast up to the level of the dowels. That's about 20mm. Is that 2 x 10cm layers or should second layer be thinner?

Thanks again.

 

[Bendunk]

This has previously been discussed in various posts. A pure cement board, such as Hardiebacker, is what BG refers to. It's a lot simpler than the other options. Don't use Vitcas on sand and cement; they're two different materials that I don't believe will mix well; instead, use one or the other. If you want an open fire, you should replace the fireback chair and throat, among other things, so that it has a chance of working and creating some radiant heat. i suggest to you Resin driveway materials for this process you can contact to them. they can help you with cheap prices.

 

[Brimstone]

This has previously been discussed in various posts. A pure cement board, such as Hardiebacker, is what BG refers to. It's a lot simpler than the other options. Don't use Vitcas on sand and cement; they're two different materials that I don't believe will mix well; instead, use one or the other. If you want an open fire, you should replace the fireback chair and throat, among other things, so that it has a chance of working and creating some radiant heat. i suggest to you Resin driveway materials for this process you can contact to them. they can help you with cheap prices.

WTF Bendunk ? My post and you add some crap about resin driveways?

 

[worthwords]

Thanks all, for your replies. Picture attached of the current state. I'm picking away at the old 60's(?) concrete and tile fireplace, wondering how far to go. Dont fancy whole inner fireplace refurb. Way out of my comfort zone. Revealed arch of bricks too with same height mantle piece indents cut out of wooden corner dowels.

So it's looking like I'll s&c the chimney breast up to the level of the dowels. That's about 20mm. Is that 2 x 10cm layers or should second layer be thinner?

Thanks again.

Lime putty based coat is prefect option for fireplaces. It tolerates heat and you can finish with a very fine plaster for very little material costs.

My 1930s fireplace had a 70s treatment with a brick heath which was soaking due to a cement and DPM.
I took it back down below the floor level and put in a slate hearth which lips over the floor boards. Then few tubs of lime mortar to dub out the bricks and built up to smooth plaster. It has survived 2 years of heat cycling with the wood burner hotter than an open fire where much of the heat goes up the chimney!

 

[zombie]

Lime putty based coat is prefect option for fireplaces. It tolerates heat and you can finish with a very fine plaster for very little material costs.

My 1930s fireplace had a 70s treatment with a brick heath which was soaking due to a cement and DPM.
I took it back down below the floor level and put in a slate hearth which lips over the floor boards. Then few tubs of lime mortar to dub out the bricks and built up to smooth plaster. It has survived 2 years of heat cycling with the wood burner hotter than an open fire where much of the heat goes up the chimney!

View attachment 63758

View attachment 63759

View attachment 63760

Nice moon landing on left hand lower

 

[worthwords]

Nice moon landing on left hand lower

ha. The top coat is marble flour + lime which gives this colouring. I since finished it with claypaint which is also heat resistant.

 

[FreeD]

Don't use sand and cement it will crack

I've done loads of openings. You need hardibacker 12mm. Prime brickwork then dot and dab boards on to get them level back and sides. Once dab has dried secondary fix hardibacker with screws to brickwork (countersink). Use heat resistant caulk for internal corners. Fill screw holes are with interior filler. You should be able to do most without joints...but I sometimes have horizontal joint at back which I skim over with the internal corner caulk...(won't be seen anyway as burner will cover most of joint) Paint white, install burner.

 

[John j]

Dot n dab it . Then put a duplex electric fire in . You won't ever turn fire on no one dies but you can flick effect and it looks like a burner but with no heat , mess or wood yard in back garden

 

[carys]

Hi, I'm hoping to plaster our dining room in a small victorian end terrace house. Much of the old plaster is blown so I've removed it all including lath and plaster ceiling.

I plan to plasterboard and skim ceiling, dot & dab and plasterboard walls and alcove either side of chimney breast.

Question is, how to I deal with chimney breast with open fire? British Gypsum say not to use their products and find cement based plasterboard.

Internet research points to sand, cement (scratch and top coat) with victas or ever build heat resistant plaster on top.

Any thoughts or advice would be much appreciated.

Sand cement inside make good outside and over skimmed!

 

[Brimstone]

Don't use sand and cement it will crack

I've done loads of openings. You need hardibacker 12mm. Prime brickwork then dot and dab boards on to get them level back and sides. Once dab has dried secondary fix hardibacker with screws to brickwork (countersink). Use heat resistant caulk for internal corners. Fill screw holes are with interior filler. You should be able to do most without joints...but I sometimes have horizontal joint at back which I skim over with the internal corner caulk...(won't be seen anyway as burner will cover most of joint) Paint white, install burner.

I think Worthwords was doing only the front and has not done anything to the chamber inside.

Agree, S&C tends to crack, depends on how close the stove is, but Carys and other seems to get away with it. If you cut the boards vertically then join is behind the stove pipe. I use a similar method to you but often use floor tile cement and no screws. Tile cement fills the gaps/scew heads and is 95% OPC same as the boards.

 

[worthwords]

I think Worthwords was doing only the front and has not done anything to the chamber inside.

Agree, S&C tends to crack, depends on how close the stove is, but Carys and other seems to get away with it. If you cut the boards vertically then join is behind the stove pipe. I use a similar method to you but often use floor tile cement and no screws. Tile cement fills the gaps/scew heads and is 95% OPC same as the boards.

Yes, exposed bricks on inside the chamber but for the back. I used a 20mm vermiculite board fas an insulator as the back chimney wall single skin = heatloss outside.. Stuck to the back bricks with fire grade adhesive and sprayed black with stove paint.
I did think about doing the inside but the chamber on ours is already very small and I like the look.

I ran a IR heat camera on firepace when in full flow and the bricks easily get up to 90 degrees and next morning were still 34 degrees. So clearly gypsum not up to it and I assume S&C would be in danger of cracking unless using refractory cement.

 

[Deleted member 32554]

Yes, exposed bricks on inside the chamber but for the back. I used a 20mm vermiculite board fas an insulator as the back chimney wall single skin = heatloss outside.. Stuck to the back bricks with fire grade adhesive and sprayed black with stove paint.
I did think about doing the inside but the chamber on ours is already very small and I like the look.

I ran a IR heat camera on firepace when in full flow and the bricks easily get up to 90 degrees and next morning were still 34 degrees. So clearly gypsum not up to it and I assume S&C would be in danger of cracking unless using refractory cement.

View attachment 63907

Thought gap was supposed to be150 , looks tight

 

[worthwords]

Thought gap was supposed to be150 , looks tight

Nah there’s no official requirement with non combustibles just stove guidance. The HETAS guy sourced an appropriate burner with back flue which pushes it forward 300mm from the back wall.
While not ideal size . With a stove fan to improve circulation it works very well