Cracking Plaster Behind new 5KW Woodburner


Postby Nick1234 » Tue Jan 05, 2016 8:18 am

About 2 years ago we had a 5kw wood burning stove installed in our living room. We had no chimney breast so it was installed in front of a plaster wall, with a length of uninsulated pipe, followed by twin wall pipe which runs through the ceiling.

Behind the stove is Victas heat resistant plasterboard, and then Victas heat resistant plaster. This is only directly behind the stove. When it was installed, it was left for about two weeks to dry before being painted, and the stove wasn't used for approx another month.

Over the last two months of using the stove, cracks have appeared following the line of the plasterboard. The cracks are getting slightly wider, and I assume it is caused by the plasterboard expanding and contracting as it heats and cools. This is then causing small hairline cracks in the plaster elsewhere in the wall. There are also big cracks appearing directly behind the stove.

Picture are attached showing the stove, and some close ups of the cracks.
Should this be happening with heat proof plaster and plasterboard?

Can anyone help with options to resolve? So far I have thought of the
following:


I've thought about digging out the cracks and filling with some flexible
polyfilla, and then painting over. I'm worried the cracks will just
reappear, and also that painting over the flexible polyfilla will look
obviously different to the rest of the wall.


Digging out the cracks and filling with normal plaster, in the hopes it has
expanded and contracted as much as it will do, but again worried they will
reopen.


Tiling straight over the plastered wall and hoping it dissipates the heat
enough to avoid the plasterboard expanding and contracting.


Cut a square of plasterboard out of the wall the width of the hearth and
slightly taller than the stove, and tile straight onto the brick behind to
ensure maximum heat distribution.


What would be the best option?

topcrack.jpg
Crack above the fire

crackbehindfire.jpg
Crack behind the fire

sidecrack.jpg
Crack to the right

fullfireplace.jpg
Full fireplace
Nick1234
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Postby tileclipproman » Thu Jan 07, 2016 8:58 am

Try filling the cracks with normal filler while the wall is warm,where there is fierce
heat there is always an amount of hairline cracks.Try fireing up the stove slowly so the wall has time to absorb the heat.
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Postby oneoone » Mon Aug 22, 2016 10:45 am

Im not sure if this helps but when we got our wood burner ( also 5KW ) the guy that installed it insisted that we got hardibacker fitted to the walls to prevent the paster from cracking, We have never had a problem so it maybe worth getting some fitted.
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