Cassette fireplace

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Plaster159

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Hi

I've ran a search but can't seem to find the answer.

I've purchased a house with a cassette fireplace which pumps out some heat.

The skim 3" above the fire has kind of shrunk, I've asked a couple of friends who are plasterers to have a look and they recommended hacking away the pink plasterboard about a 400 mm above the fire and replacing with hardiebacker then finishing the whole chimney breast with heat resistant plaster. Unfortunately the new heat resistant plaster is now coming away from the top of the chimney breast, it looks like it's only a couple of mm thick, they did PVA the old skim plaster beforehand. Any ideas on what they ought to be doing next.

Any help would be greatly appreciated
 
Can you put any photos on?if the skim has shrunk on the plasterboard sounds like it didnt dry properly before they turned the heating on
 
Hack off back to brick or block all round the fire (600mm )render & skim with victas products
 
church said:
Hack off back to brick or block all round the fire (600mm )render & skim with victas products
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Sorry, should have added its a false chimney breast what looks like a steel frame. Also the fire hasn't been turned on yet following the reskim.
 
Plaster159 said:
Sorry, should have added its a false chimney breast what looks like a steel frame. Also the fire hasn't been turned on yet following the reskim.
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Oh. Was thinking it might have been heat related but if the fire's not been on??? If you could put a picture up it would be better to see. A picture paints.....
 
leemiff said:
Can you put any photos on?if the skim has shrunk on the plasterboard sounds like it didnt dry properly before they turned the heating on
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struggling with pics from my phone, but large foot long cracks have appeared where the plasterboard and board finish was replastered it looks as if it hasn't bonded and is coming away in large pieces
 
aint that heat resist stuff a one coat product? like er y'know.. er one coat plaster?? maybe thats yer problem right there... should have hacked it right back like church said and gone again from scratch... maybe? Cassette fireplace
 
so what your saying is ,its metal stud frame with pink fire line board skimmed with a heat resistant plaster and its cracked before the fire has been turned on ? , sounds like the frame is not strong enough to take the weight of the fire maybe ??
 
I'd be tempted to pull it all off, board and all and re do it I think. Or scrape all the loose stuff off completely fill it out and over skimm in heat resisting plaster.
 
Yeah metal stud frame, in pink plasterboard skimmed with board finish. All was good but about two inches above fire which kind of crazed but was solid. 400mm of plasterboard was cut away and replaced with hardiebacker then the whole chimney breast reskimmed in purimachos (everbuild) PVA'd beforehand. Now the HRP is just falling off from plasterboard.

Metalwork is is sound cos the pink plasterboard was fine.
 
a fireplace should be blocks, if you need to use boards on the actual insert of the fireplace you should use glasrock board, like fireline board but more fire retardant. and some drylining material(easyfill) as multi-finish wont stick to it. think whoever did the job did it wrong possibly, maybe even dangerously.
 
raytheplasterer said:
a fireplace should be blocks, if you need to use boards on the actual insert of the fireplace you should use glasrock board, like fireline board but more fire retardant. and some drylining material(easyfill) as multi-finish wont stick to it. think whoever did the job did it wrong possibly, maybe even dangerously.
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That would work I guess with something like a wood burner, but this is an inset hole in the wall gas fire.
 
doesn't make much difference, fireline board is not designed to be used in spaces with excessive heat, it's meant to last longer than other plasterboard in the event that it needs to.
 
seems to me some one had a idea on what might just look good , and not given a toss on the out come , next directory fire ?
 
raytheplasterer said:
doesn't make much difference, fireline board is not designed to be used in spaces with excessive heat, it's meant to last longer than other plasterboard in the event that it needs to.
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I agree fire line is not suitable, but the original skim coat was fine on the majority of the chimney breast and the board joints weren't cracked, I'm minded to get it reboarded in hardiebacker or supalux then reskimmed in HRP. Just thought whether you guys may have come across this before ripping it down.
 
i would take off the plasterboard , and have a look at the studwork , strengthen the build if needed , use a hardiebacker board , then a bonging agent then skim with vitas
 
I would have painted on Betakontakt or similar which is a better key, then the fire resistant skim which needs to be 6mm thick to work properly. Sounds like they didn't use the PvA correctly though.
 
As we all should know, there are 2 things in particular that multi bows not like. Dampness and Heat. Could there be condensation on the back of the board in the void behind? Caused by heat from the fire? Loads of expansion and contraction going on there.
Basically it sounds like a design fault.
 
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