I have a masonry chimney and need to seal between the chimney and the joist. I have FTX so I'm getting insulation from the attic, it's probably being sucked in through the gap between the chimney and the joist. There's about a 1 cm gap between the construction board and the chimney, and there are metal studs on the top side. What type of sealant can be used here? I prefer a flexible sealant, not silicone.
I see that I need to clean the chimney a bit... I've been a bit careless when I built it.
Oh. One usually goes against it with a trim, but not with larger pieces of combustible material against the chimney. Even if this one looks very tight and nice.
"Flue channels with an outer temperature of at most 80 degrees C should have a distance between the channel wall and combustible building part of at least 10 cm. The space between the channel wall and the combustible building part should be ventilated. Edges of floor coverings, ceiling panels, or trims of wood covering a smaller part of the channel wall's exterior can be placed in contact with the channel walls unless the flue channel is made of steel or cast iron."
The normal practice is to let a frame around the chimney contain only mineral wool insulation. So, other insulation, loose fill, or whatever you have is separated, and only mineral wool panels are placed closest to the chimney.
Hello norrbottenstorpet!
Yes, I understand the usual method, but it doesn't work because it doesn't become "gastight."
We have negative pressure in the house and will draw in air through the insulation which acts as a barrier. I have about 12 cm to the beam from the chimney, then the paneling extends to the inside of the chimney where there are metal studs to prevent it from becoming too unstable. I would like to fill the space between the metal stud and the chimney to make it "gastight."
So I was thinking of sealing between the metal stud and the chimney.
Possibly folding a heat-resistant fabric and pushing it down in between, then packing it with material
The fabric would then be pressed against the stud and chimney to seal. The packing presses the fabric against the walls. The fabric is tight so it will not leak between the chimney and the stud.
For packing, you can use rock wool, but what should the fabric be?
It would be easiest to spray in soft sealant instead of packing.
I have to put something in because I have loose-fill insulation on the attic, not just that, but some parts were difficult to insulate with panels.
