Woodburner flue penetration through ceiling

[regsmyth]

I have installed my woodburner and the vitreous steel flue changes to a stainless twin wall flue about 150mm below the ceiling, which then extends up through the loft and roof.
How to seal where the flue goes through the ceiling?
I was supplied with a thin sheet steel plate which has a hole approx 10mm bigger than the twin wall, and vertical tabs that presumably should indicate the plasterboard stopping 50mm from the flue. Now clearly I can't have a gap, so what is the point of this plate?
Above the ceiling plasterboard is 90mm of kingspan fitted between the joists.
The twin wall doesn't really ever get hot.
All I've done so far is cut the plasterboard back 50mm from the twin wall, and cut a hole through the kingspan just slightly bigger than the twin wall, the gap I sealed with pu foam.

Any advice welcome, thanks.

 

[joinerjohn]

I always thought woodburners should be installed by a Hetas registered installer?

 

[Richard C]

I always thought woodburners should be installed by a Hetas registered installer?

Either that or you should notify LABC who will inspect the installation & probably want to witness smoke tests. Have you checked or are aware of the Building Regulations you need to comply with for a stove installation? I advise you either consult a HETAS installer or do some more research before you either;
1. Poison yourself
2. Burn down your property
3. The ceiling falls down when the plaster board fails due to excessive heat.

& then your insurance company probably won’t pay out & declare your claim null & void if you can’t produce a certificate of compliance.

 

[regsmyth]

LABC will check and sign it off when done. They already have drawings showing the installation. It all conforms. I just want to know about the sealing around the ceiling bit. Thanks.

 

[jeds]

Most flue manufacturers make a range of cover trims for this purpose. Try your manufacturer first but try others of they don't have what you need.

I would also fit mineral wool into the gap between the Kingspan and the flue wall in the ceiling void. It would also be wise to double up the insulation about a metre around the flue if you can.

 

[regsmyth]

Thanks, I think I've got it now. As per regs, the plasterboard and kingspan should be cut back 50mm from the twin wall, then the steel plate (firestop spacer) fixes to the ceiling, and the 5mm gap between the twin wall and the plate is filled with fireproof sealant.
Then I'll pack fibreglass around the twinwall above the ceiling plate.
I can paint the plate to make it look a bit better.
Thanks for the pointers.

 

[Richard C]

LABC will check and sign it off when done. They already have drawings showing the installation. It all conforms. I just want to know about the sealing around the ceiling bit. Thanks.

Just checking
If there is any heat in that flue liner I would watch the plasterboard; I know it’s classed as non flammable for B Regs but 50mm is pretty close & if the temperature regularly exceeds 50C there is more than a good chance it will fail.