Fireplace / chimney mould?

30 Oct 2021
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United Kingdom
Hi, can anyone confirm whether the black stuff in the photos is mould? I think it may be mould but perhaps covered in dust, so I’m not sure. The photos are from an old disused fireplace that is now simply a hole in my bedroom wall with a breeze coming through it. I’m on the top floor with two flats under me but not sure if they have disused fireplaces connected to the same chimney (I’m in London, so they’re not in use anyway). Thanks very much for any advice.


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The black stuff is soot.
Its good practice to remove all the loose rubble and dust form redundant fireplaces.
Your flue needs sweeping - unswept flues can damage your chimney breast decorations.
The breezy flue also needs a correct anti down draft cowl installing at the top.
Each fireplace in the building has its own flue - flues never join or mix, When 2 or 3 flues run up in the same chimney breast they are kept separate by brickwork called feathers.
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