Chimney stack building??? Please help!

celtboy1888

sorry if in wrong section.


i need to get hold of documents that state the correct way to build a chimney that protrudes from a roof, i.e like in a dormer bungalow, the info i need is vital to a job i am doing at the moment, i need to know the exact way it should be built, the cavity's insulations, etc,

iv been advised that any chimney that is external should have a cavity between the block work and the liners inside, regardless of the back fill around the clay liners.

please help.

p.s ..iv checked buliding regs 2007, and home bond..cant see the info there:(

mickdw

If its out through the roof, it wont have a cavity.
If it is on an outside wall coming up at the edge of the roof, the cavity will run around the outside of the chimney.

celtboy1888

is it possible to get documents to say same??

tnkx

Poor Uncle Tom

celtboy1888 wrote: »

is it possible to get documents to say same??

tnkx

What documents are you looking for? It's down to good detailing.

Pages 29, 30 & 31 might help you out.

celtboy1888

the main issue im trying to resolve is the possibility of a liner heating up during a fire and expanding enough to crack the block work and or plaster on the outside of the stack, the house in question is a dormer bungalow, an architect mate told me any stack that comes out side the roof like a dormer has to have a cavity...maybe i picked him up wrong?!?!?

mickdw

Whats the chimney like? What dimensions are you building it? one flue or 2? Is it on an external wall or visible on external wall?
The liners must be free to expand with heat. The fill around the liners must therefore be a loose fill material. If 2 flues in this chimney, it will need a wall dividing the flues and still have adequate room for loose fill around them.

Are you actually building this yourself? - as in blockwork? Is it your first time? Any training?

celtboy1888

one flue, solid fuel stove, approx 12ft from lowest point of exit from the slates/roof, no it is a problem im trying to get to the bottom of.

no not building it.

mickdw

celtboy1888 wrote: »

one flue, solid fuel stove, approx 12ft from lowest point of exit from the slates/roof, no it is a problem im trying to get to the bottom of.

Cant see any special requirements there. It will just amount to a blockwork outer, with flue liner inside and some space for the fill between the liner & the blocks. Given the freestanding height, I would build it with block on flat at either end. Check out homebond for height requirements in relation to distance from ridge etc

celtboy1888

mickdw wrote: »

Cant see any special requirements there. It will just amount to a blockwork outer, with flue liner inside and some space for the fill between the liner & the blocks. Given the freestanding height, I would build it with block on flat at either end. Check out homebond for height requirements in relation to distance from ridge etc

the main issue im trying to resolve is the possibility of a liner heating up during a fire and expanding enough to crack the block work and or plaster on the outside of the stack, the house in question is a dormer bungalow, an architect mate told me any stack that comes out side the roof like a dormer has to have a cavity...maybe i picked him up wrong?!?!?

mickdw

celtboy1888 wrote: »

the main issue im trying to resolve is the possibility of a liner heating up during a fire and expanding enough to crack the block work and or plaster on the outside of the stack, the house in question is a dormer bungalow, an architect mate told me any stack that comes out side the roof like a dormer has to have a cavity...maybe i picked him up wrong?!?!?

Im sure you picked him up wrong.
The loose fill is to allow expansion of the flue liner.
Surely all chimneys come outside the roof?
Perhaps you are just confusing it with the case of an external chimney on an outside wall - this would form the inner leaf with an outer wall creating a cavity.
Also, you will need to have the the chimney dimensions approved structurally by your engineer as the 12 ft height is alot.

mail

Ask the Architect to detail it for you if he is telling you how to do it !