Chimney/flu experts

[walls]

Newbie with a strange question probably. I live in an old 100+ mid terrace. It seems to have had a very dodgy roof later in its life and water has caused damage to the chimney flues to the extent they are in a bad way being propped up by some wooden supports. Everything is dry now and nothing is moving but I'd imagine rebuilding the flues would be an expensive/painful job?

I want to convert the attic at some point and fit some wood burners in the fireplaces down stairs. My question is, do I really need this flues and could they be taken out in the attic space - the wood burners could be connected to the chimney by metal flues that pass through the attic space? I presume the brick flues aren't structural otherwise our survey would of mentioned it?

cheers

 

[Shytalkz]

I presume the wooden supports are like an upside down V under the gathers? In which case they are likely to be original and not a later attempt to prop up an ailing structure.

Yes you could remove the flues, but you will need SE advice.

 

[walls]

Thanks for the reply. Yes the wooden supports are as you describe, I hadn't realised they were original. The outer flues which served the bedrooms and chimney pots have been removed as I think they were beyond repair. The remaining flues just seem to be propped up by these supports. Is that really all that holds them up?

How is a chimney stack usually supported in a mid terrace? It's pretty large so maybe have to be taken down if the brickwork below is removed? Then I guess, I'd get into all sorts of planning complication stuff.

Can you clarify what SE advice is?

Many thanks.

just worked it out SE=structural engineer!

 

[Shytalkz]

If you're mid-terrace, then the stack is shared with the neighbour. You can take half the flues down within the roofspace (and obviously the chimney breasts in the rooms below, but you would need to support the stack that will remain outside of the roofspace. This could be a goalpost steel frame sat on steel/s at ceiling level.

Or you can leave the gathers (the upside down Vee shape of masonry) in place and remove the chimney breasts in the room/s below, which will require the installation of steels at the ceiling level.

The gathers were intended to be self-supporting, cantilevering off the party wall masonry. However, this relies on the brickwork maintaining its integrity, but often long-term degradation of the lime mortar, through reacting with flue gases, results in the wiffs (inside bits that separate the flues) collapsing, often followed by the outer brickwork to the gathers.

Thus, if you keep the gathers and not the downstairs breasts, it's always prudent to remove the timber and infill in blockwork under the gathers, built off the steels installed at ceiling level.

 

[walls]

All clearer now...many thanks, great info.