How to seal around the stove to insulation pass through?

[Andehh]

We have 150mm insulation in our warm roof, insulated flu passes through it, but the installer explained has to be a 50mm zone around the flu.

 

Is is simply the ''done thing'' to keep this 50mm an accepted cold spot going through the roof? Has anyone used vermiculate or rockwool around it?

 

I figured they are non-combustibles and at the 2m height above the fireplace the stove insulated flu will not be so hot as to damage them.

 

Welcome thoughts - thanks 

[ProDave]

When I bought my flue pipe, I bought an "insulated sleeve" made for the purpose.  It fits tight around the flue and because the manufacturer has declared it for for being in contact with the flue it must be non combustible so that is fine.  And the outside edge is >50mm from the flue so anything can touch that.

 

 

I have not been able to find this on sale lately but surely someone makes one still?

[Andehh]

That's idea! I'm hoping I can get away with handpacking vermiculite sheets tight around it, with some metal stripes to hold it up and I'm place. 

 

 

I'm worried about air tightness as well, but having been ruthlessly fastidious over the rest of the house, this area may need to be a compromise. I'll just use fire proof sealant all around all the exterior connections and hope for the best 

[JohnMo]

My twin wall flue is packed with rock wool at the suggestion of the installer, that's how they always do it.

[saveasteading]

2 hours ago, Andehh said:

the 2m height above the fireplace the stove insulated flu will not be so hot as to damage

It will be very hot indeed even up here....a lot of heat escapes from the fire and the insulated flue keeps it moving intead of escaping from  a bare metal flue into the room. Of course the flue, being insulated, is protecting the surroundings, but adding 50mm more protection is simply sensible. It also allows some movement on heating and cooling.

[dimpsy]

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

 

Think this is what your looking for.

[dpmiller]

^ yep. We used Ignis Protect to go through the walls in an airtight manner.

[Andehh]

Thanks guys, seeing as everything has already been strapped into place, best I can get is rockwool around it, and simulate the effect. Not perfect, but better then nothing.

 

Ill ring rockwool to make sure, then stuff it up there!

[junglejim]

On 12/03/2023 at 12:48, dpmiller said:

^ yep. We used Ignis Protect to go through the walls in an airtight manner.

@dpmiller this looks like what I’m looking for. Please can you advise where you bought this and how easy it was to install?

 Thank you

[dpmiller]

31 minutes ago, junglejim said:

@dpmiller this looks like what I’m looking for. Please can you advise where you bought this and how easy it was to install?

 Thank you

I think most of the Merchants can probably order from Schiedel. We ordered all our chimney stuff through NG Bells in Ballywalter as they were handy.

 

no real hassle to install, just needed to cut a hole in the OSB then it sat neatly between the studs.

[G and J]

On 12/03/2023 at 17:00, Andehh said:

Thanks guys, seeing as everything has already been strapped into place, best I can get is rockwool around it, and simulate the effect. Not perfect, but better then nothing.

 

Ill ring rockwool to make sure, then stuff it up there!

I was told by the technical guy at the company who’ll be supplying our fire, etc. that mineral wool can smell rather when used to pack around an insulated flu.  Given that peeps have used mineral wool round their flus did they find it stinky?

[Andehh]

Never noticed any smell, even when we have heated it hard. I think we have a substantial draft coming down the area though, so come the summer I'm going to remove the rain shield and have a look at the flue and our warm roof interface, and look to use some fire rated rope and adhesive or equivalent to block the gaps.

Edited January 1 by Andehh

[markocosic]

Stretchy flue rated silicone seals is what you're after.

 

 

For roof membrane:

 

https://dumtakis.lt/manzetai-membranos-dumtraukio-prasiskverbimui/947-dumtraukio-manzetas-rgd180.html#/394-stogo_kampas_laipsniais-diapazonas_0_45_

 

 

For inner airtightness membrane:

 

https://dumtakis.lt/sandarinimo-detales/356-dumtraukio-prasiskverbimo-manzetas.html

 

 

Cut your standard membrane back leaving e.g. 10 cm gap to flue. Slide the silicone job over. Tape the silicone job to your standard membrane.

 

My 'membrane' is OSB. A section of this was replaced with cement board that stops 10 mm short of the flue. This 10 mm gap was flexible sealant-ed (1500C rated) in place. Purpose: no thank you to mice indoors. They apparently do like a cosy flue in winter.

 

The silicone seal is then inboard of this and taped to the OSB at its edges. A belt and braces ring of 1500C sealant 'glues' the silicone to the flue so it's not just relying on stretching to seal.

 

Cut the flammable cladding back 8 cm around the flue (or whatever the rating is)

 

Theres then a split metal trim ring to bridge the hap/hide the mess.

 

 

Windows leak more than the flue. (all the corner welds of the uPVC)