Crack in new plaster on chimney breast above log burner

[tireetim]

I have recently had a log burner installed into a chimney breast. The block chimney was opened up and lined with a flu liner. The chimney breast was then made good and skimmed with multi finish. They used SBR on the blocks where backing plaster was needed and then used blue grit over everything before skimming. About 10 days later a vertical crack has appeared from the top of the lintel to the ceiling. It is only a hairline crack when cold but opens slightly wider after the burner has been on for a couple of hours. Can anybody advise on the best thing to do to rectify the problem? I'm guessing because there seems to be thermal expansion that just opening the crack and filling will not work. Should I insist it is re-plastered and if so how should they do it to avoid the problem. Alternatively would wallrock liner paper work and can it be used on a chimney? I am looking for a painted finish. Thanks.

 

[Deluks]

Wallrock is pretty tough stuff, you may still see the crack showing through the paper though. You should follow the stove instructions on 'distance to combustibles'

Heat resistant plaster is available.
It's debatable whether or not they should redo it for free, plasterers plaster walls, if you want a non standard plaster then it should be specified up front.

Do you have a mantelshelf or fire surround? This may be enough to block the heat rising to reduce the temperature in the wall above the appliance.

 

[tireetim]

Thanks Deluks. I think the wall heats up from the flue inside rather then from the front but I'm not 100% sure. It was a stove company that did the work so I didn't have any input into what materials they used - just let them do their thing. I was going to install a mantel but haven't done yet so maybe it will help. OK I will get them to come back and have a look but I can imagine they will do anything to wriggle out of fixing it. Good to know that Wallrock is a possibility but I see it as covering the problem rather then fixing it. Thanks for your help.

 

[foxhole]

There will be negligible heat from the liner , the stove being the main source of heat to the chimney .
Photo of installation?

 

[tireetim]

I've spoken to the builders and they think the stove has been lit before the plaster had fully dried which caused the crack. It may be the case, I'm not sure. I did what the installer told me with regards to how long to leave it before lighting. Anyway - they are coming to have a look and I think cut back the crack and fill it. I questioned if that would just come back again doing that and he said if it does they will re-skim it.