Venting a chimney

darich

Hi
I have a chimney breast in my living room and am currently lowering the chimney stack bit by bit inside my loft with the intention of taking it down to joist level and flooring over it. My attic is not a room – purely for storage.
I know that if I seal it, I’ll need a vent and it’ll be in my living room behind the fireplace. Air flow will be fine but not visibile.
My question is, do I need an additional vent at the top? And if so, how do I vent the top inside my loft without filling my loft with warm air where it will be a condensation issue?
Is one vent at floor level sufficient?

Tom99

Has the whole stack above roof level been removed?

darich

yes


Stack was damaged a while back so was reduced in height and the roof repaired over the top of the stack.
Now I want to lower the height of the stack inside the loft down to joist level.
It would be a reduction in height of about 1200mm. And with the flooring over it, it would effectively be sealed at the top.


Unless I need a vent at the top too.


I could run a plastic pipe to a vent tile a couple of metres away and it would be under the flooring

ed110220

You definitely don't want to create an air path from the living area into the loft as that will cause unnecessary heat loss and could cause condensation problems in the loft.

Tom99

Once the brickwork has dried out does it need a vent?

nickcc

Just leave the old stack opening open as I did. The damp on the internal walls where the stack goes soon drys out if the stack has been lowered below the roof line.

darich

Thanks all


I've taken further advice and it looks like venting at the bottom should be sufficient...so that's my next job!

troffasky

https://readinguk.org/draughtbusters/going-further/heat-loss-from-chimneys/