Wood stove causing structural damage?

[Deleted User]

I posted this on the energy board but I didn't attract many replies so I hope more people may see it here.

I have an inset stove, with 6 inch granite slips around it installed in the autumn 2013. It's a modern house built in 1986 with a chimney that used to house a gas back boiler. No liner as the flue is concrete, I have a certificate etc from the hetas approved fitter.

A fine horizontal crack appeared along the line where the old fire surround had been (removed and skimmed by the previous owner) which I filled several times with heat resistant filler but it came back each time. The chimney breast gets very hot directly above the fire and gradually cooler further up the wall.

In the last couple of weeks 2 very fine vertical cracks have appeared starting from the slips. The fitter is coming to see it this week and as I'm a female alone I want to be armed with as much advice as possible please. I'm worried about the hot wall above the stove and the cracks. Has anyone any ideas on this one? Apparently it's a class A chimney but I don't know if that's true

POPPYOSCAR

A fine crack skimmed over will always come back again in my experience.

You have to chisel out and fill in properly.

Gloomendoom

If the cracks are just hairlines in the plaster they are unlikely to be structurally significant. The chimney breast will be expanding and contracting every time you use the stove so some cracking, particularly at joins, is (almost) inevitable.

[Deleted User]

Thank you both! That would explain the cracks but what about the wall being too hot to touch?

Gloomendoom

I can't really comment on that. Both chimney breasts in use in our house stay absolutely cool no matter how hot the fire is. Neither are lined.

muckybutt

It would possibly be worth while lining the chimney with a liner and back filling with Vermiculite insulation if the chimney breast is getting too hot to touch.

[Deleted User]

muckybutt wrote: »

It would possibly be worth while lining the chimney with a liner and back filling with Vermiculite insulation if the chimney breast is getting too hot to touch.

Thanks MB the installer said a liner wasn't needed and it was back filled with vermiculite.

muckybutt

Ah I see ... class 1 - it will be a clay lined chimney then roughly 10" wide.

Hot hot does the chimney breast get ? Our stove runs at around 320f when it's on and the chimney breast gets moderatly warm to touch.
If yours is getting too hot then the way forward would be to line even though you have a class one chimney and back fill it as I suggested, won't be cheap though as you would be looking at around 50 - 65 quid per meter of liner + the vermiculite back fill.

As for the damage, the hairline cracks are nothing to worry about, our chimney dates back to 1850 and has all sorts of hairline cracks here there and everywhere, I have even come across chimneys that have caught fire and very rarely do they get that badly damaged they can't be used or become unsafe.

Personally speaking I would say you have nothing to worry about, can you post a photo of the cracks and stove ?

the_matrix

Hairline cracks nothing to worry about.

Maybe go for the brick effect instead of plaster? That will solve the problem forever.