Calcium silicate as a firewall, what applies?

[Anna_vedpanna]

I've placed a 5 cm thick calcium silicate board on the wooden wall behind the stove, but my concern is whether it's sufficient behind the flue pipe which is only 5-10 cm away. I'm considering taking it down and sawing apart the top boards which are unnecessarily wide, and having double boards behind the pipe. What do you think? Is it excessive?

 

[Danne824]

I've placed a 5 cm thick calcium silicate board on the wooden wall behind the stove, but I'm wondering if it's enough behind the smoke pipe, which is only 5-10 cm away. I'm considering taking it down and cutting the top boards that are unnecessarily wide and having double boards behind the pipe. What do you think? Is it overkill?

You get the distance from the manufacturer of the smoke pipe with and without the fireproof board.
Even if you double the fireproof board from 50 to 100 mm, it doesn't automatically mean you can halve the distance required to combustible material.
And in your case, the smoke pipe will be right against the fireproof board?

Is it an uninsulated smoke pipe you have even at the ceiling passage? It looks like that in the picture.
If so, what do you have on the second floor, and how large is the hole?

I have to be honest and say that the installation of the fire boards doesn't look very neat.

Do you need it to be so wide around the stove and all the way up to the ceiling?

 

[Matti_75]

I also don't think your pipe fittings are approved as they lead heat into the wall behind the panels.

 

[Anna_vedpanna]

You get the distance from the manufacturer of the flue pipe with and without fireproof board. Even if you double the fireproof board from 50 to 100 mm, it does not automatically mean you can halve the required distance to combustible materials. And in your case, the flue pipe will be flush against the fireproof board?

Do you have an uninsulated flue pipe even at the roof passage? It looks like that in the picture. If that's the case, what do you have on the second floor and how big is the hole?

I must be honest and say that the installation of the fireproof boards doesn't look very neat.

Do you need to have it so wide around the stove and all the way up to the ceiling?

I did this myself and am no expert. No, you can probably saw off a part of it if you want, but the boards are insanely dusty so I'd rather avoid it. It's a Jøtul from the 60s, likely the pipe is from them as well. Above the ceiling, it looks good, insulated, etc.

 

[Anna_vedpanna]

I don't think your fixings of the flue pipe are approved either since they lead heat into the wall behind the panels

I've thought about that too, but the inspector didn't mention it when they last looked. They specifically recommended that I should place potassium silicate boards along the wall, without mentioning the fixings at all. Hopefully, they won't change their minds. The stove has been in use since the 1960s and it has never been a problem.

 

[Danne824]

I have done this myself and am not an expert. No, you could probably saw off a part if you want, but the boards create a lot of dust, so I prefer not to. It is a Jötul from the 60s, likely the pipe is from them as well. Above the ceiling it looks good, insulated, etc.

😃 I am also a happy amateur.

What I meant is that you could place the fireproof boards vertically, then you wouldn't need to cut out for the light switch.

In other words, not cover the entire wall, not so wide.

I agree that it creates a lot of dust when cutting into the boards and they are sensitive to marks.

I remember an old Jötul has the requirement of 500 mm to combustible materials (stricter requirements for the back and sides), and with the board 100 to 150 mm.

For the chimney pipe, the distance is 300 mm and with the board 100 to 150 mm.

I don't think you should use double boards, purely for aesthetic reasons. But check with the chimney sweep what they think, they're the ones who need to approve the installation and the chimney pipe is closer to the wall than the stove.

Has the stove been installed since the 60s, and they are now making remarks?

 

[Anna_vedpanna]

😃 I am also a happy amateur.

What I meant was that you could stand the fire-resistant boards vertically, then you wouldn't have needed to saw out for the switch.

So, not cover the entire wall, not so wide.

I agree that it creates a lot of dust when sawing the panels and they are quite fragile for marks.

I remember that an old Jötul has the requirement of 500 mm to combustible materials (back and sides stricter requirements), and with the board 100 to 150 mm.

For the flue pipe, the distance is 300 mm and with the board 100 to 150 mm.

I don't think you should double the panels, purely aesthetically.
But check with the chimney sweep what they think, they are the ones who have to approve the installation and the flue pipe is closer to the wall than the stove.

Has the stove been installed since the 60s and are they now raising objections?

When I measured from the stove to the combustible material, the boards needed to be that wide, at least up to the top of the stove, whereas the flue pipe doesn't need to be that wide. I considered placing them vertically, but there was something about the measurements from the stove that made me do it the way I did. If they accept 10 cm from flue pipe to the board, then I'm safe.

Yep, it's been there since the 60s, but there's some authority that started doing inspections like this in the last 3 years or so.