Size of hole for wood burner flue exiting a wall

[Ralph]

We are getting prices for installing a wood burner.

 

The flue is likely to be exiting the wall on the ground floor which is a Scotframe closed kit. The wall is load bearing so has load bearing studs in it which obviously I would need to avoid, I'm pretty sure they are at 600mm. I've marked the general area for the flue in the image below. 

 

My understanding is that I would need to cut a 320mm hole for the flue to accommodate the twin wall, fireproof collar etc. Does that sound about right? I will be getting a HETAS installer to do the work, I just wanted to see if it was feasible. 



 

[ProDave]

Yes that is what you need.  But why exit there?  Ours goes up inside the room, up through the bedroom above and out through the roof.

 

Don't forget a smaller hole, lower down about 100mm diameter for ducted air intake.

[Ralph]

Thanks @ProDave

It would be coming up through an open plan floor. In the image below the stove would be to the left of the TV. I suppose the other option would be to put it in the corner so it comes up through the floor near that upright radiator. We could remove the radiator, it's never on.

 

 

 

[ProDave]

If you take it up outside, it will have to be quite tall and with stays.

 

How about up the corner, then following the roof line and out at the ridge, a bit like ours in the bedroom, though in your case as close in to the roof line as you could get it.

 

[Ralph]

That's a thought. The flue will have to be almost as tall as the roof line to avoid the velux windows we have. The only thing that bothers me about coming out the roof is how crap the roof flashing will look on our standing seam.

 

[dpmiller]

If you're going through the wall and want to retain airtightness you want a

 

https://www.schiedel.com/uk/products/additional-ranges/ignis-protect/

[saveasteading]

6 hours ago, Ralph said:

how crap the roof flashing will look on our standing seam

That's the problem with standing seam. No penetrations then someone cuts a big hole in it that is impossible to flash efficiently.

 

Can you get the outlet near the ridge. That will reduce the leakage risk and not need stays.

 

PD Is right about the stays, and they have to be solid, not cables, in your situation.

 

If you do cut through the wall you can cut 2 x elliptical holes. Sums required for size and positions.

[Ralph]

11 hours ago, saveasteading said:

That's the problem with standing seam. No penetrations then someone cuts a big hole in it that is impossible to flash efficiently.

 

Can you get the outlet near the ridge. That will reduce the leakage risk and not need stays.

 

PD Is right about the stays, and they have to be solid, not cables, in your situation.

 

If you do cut through the wall you can cut 2 x elliptical holes. Sums required for size and positions.

I think we are going to have to go out the wall. Solid stays is really the only option especially with the wind we get here. It's starting to feel like job not worth doing.

[saveasteading]

Flues don't necessarily look bad. After all, new houses even put fibreglass dummy chimneys on because people expect to see them.

Do children still draw a chimney on a house because that is 'normal'?

[Ralph]

Yeah, we just need to make sure the fitter is neat. I mocked up a pic and I guess it might be OK.

 

[saveasteading]

Great pic. Have you checked the height rules? I'm not saying this attachment is correct but I found it quickly.

[Ralph]

I think the one that affects us is to make it 600mm above the top of the velux 

[Ralph]

On second thoughts that may be 1 meter in Scotland

 

[Ralph]

On 16/03/2023 at 17:20, dpmiller said:

If you're going through the wall and want to retain airtightness you want a

 

https://www.schiedel.com/uk/products/additional-ranges/ignis-protect/

Do you mind me asking what sort of price that is?

[dpmiller]

5 hours ago, Ralph said:

Do you mind me asking what sort of price that is?

 

it's a few years back and the invoice isn't to-hand but IIRC it was £2-300?

[Ralph]

1 hour ago, dpmiller said:

it's a few years back and the invoice isn't to-hand but IIRC it was £2-300?

Excellent, thanks for that.