Thistle Hardwall

[cwhaley]

I've just about finished the building work before putting in another log burner.

Where I had to remove plaster around the opening on the chimney breast face, I've used Hardwall leaving 2-3mm for the final top coat of multi finish (see pic). I'm worried however, that the multi finish will crack from the heat of the fire.

The walls inside the opening are brick, then concrete board, then tiles so I'm not concerned about heat there; it's just on the chimney breast face. Hardwall seems to be quite workable - would it be acceptable to put another layer on the existing stuff , getting it as smooth as possible, letting it dry for a month, then painting?

 

[Doggit]

It'll partially depend on the log burner you're going to use, and the distance to the walls. If you've got a steel burner with little insulation in it, then the heat will be radiating from every surface, so the chimney breast will get hotter, and if it's a tight fit, then it'll be worse.

 

[cwhaley]

We've got a cast iron one, with fire bricks to the sides and rear. It's a 4.5Kw one with 4 ½" either side to the walls.

 

[Doggit]

But how good are the fire bricks in it; will it throw the heat forwards. What are the installation instructions for the stove. I'm afraid that it may be that you've got to widen the opeing before you go much further, and that in itself would protect the harwall etc from cracking - I don't hink it's likely to, but a wider opeing will also help the hot air to circulate. How far will the stove sit into the room, and which model is it.

 

[cwhaley]

Thank you for the input. The firebricks are what they are - they divert as much heat as they can back into the stove and out without taking up to much firebox space. They're undamaged and original.

The instructions state a minimum gap of 3" around the sides of the stove (I have over 4") and 2" at the back (I have 3"). In terms of sitting inside the room, around a quarter of it will stick out from the opening. It's all built to a standard better than the regs and the manufacturer's recommendations. Not the biggest gaps I know.

Can hardwall be used without a multi-finish coat and then painted?

 

[Doggit]

It'll have a rough finish, but if the hardwall can handle it, the multifinish should as well, and whilst I've seen some people worry about angle beads getting hot and expanding, that shouldn't be a worry either. But I'd be inclined to see if you can get the stove further into the room using a bend in the flue if possible.

 

[cwhaley]

It'll have a rough finish, but if the hardwall can handle it, the multifinish should as well, and whilst I've seen some people worry about angle beads getting hot and expanding, that shouldn't be a worry either. But I'd be inclined to see if you can get the stove further into the room using a bend in the flue if possible.

Thanks, gives me some food for thought. Stove isn't in place yet so I will have to look at the 45 degree pieces which would allow me to bring the stove further forward. Would alleviate my worries over plaster cracking.

I must admit I also worried about the angle beads, which is why I've been using strips of timber to mould the plaster at the edges.

 

[Doggit]

Nothing wrong with the way you're doing it. It may not be the best of finishes, but sometimes fireplaces look good being a bit rustic. If you use a piece of melamine faced chipboard, you'll get a good edge.