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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorluz13827
    • CommentTimeNov 7th 2021 edited
    We've removed a chimney breast, which has left black marks, I assume soot.

    Have two concerns - health and then getting this wall back to standard.

    Would the best approach be to try chisel off the front of the bricks where the soot marks are? A bed will go against this wall, so I'm a bit concerned about the soot being toxic if left.

    And then are there recommendations for repairing and levelling this wall - would something like Baumit RK 38 work? Before then boarding over. We are trying to stick to lime and clay plasters as much as possible, but let me know if you think something else would be better.
    • CommentAuthortony
    • CommentTimeNov 7th 2021
    Soot will bleed through both water based and oil based sealants. Shellac will hold it back but difficult to apply.

    If it was mine I would cover with aluminium foil then poly, then expanded metal and plaster.

    Unlikely to get health effects, all the volatiles long gone just don’t eat or breathe the dust from it
    Is it a party wall or an external wall, and is it 9 inch or more?

    If an external wall of a least 9 inch, think I'd want to investigate - e.g. drill the mortar out from around a brick (not a header, of course) and then cut the brick open (hammer and bolster) to see how far into the brick the 'soot' has penetrated. If it's a long way (how easy the brick is removed will be a good indication), I'd probably cut out all the blackened bricks and make good, preferably with usable old bricks lying around. I'd then spatterdash (1:1 washed sand/ cement) and then plaster. Might have to think about maintaining structural strength where the headers are.

    If it's just soot on the surface (if it's a bedroom the fireplace might not have been used much) I'd scutch the black bits, clean off the soot and spatterdash etc.

    However, if it's a party wall, then the kind of 'cover up' bodge that tony mentions might be best.
    • CommentAuthorluz13827
    • CommentTimeNov 7th 2021
    Thanks both - it is a party wall. Good to know it's likely not going to cause any health effects, that was main concern about doing a 'proper job' of cleaning it up/removing it.

    If it's a party wall, is sand/cement fine to use to repair the wall? For external (solid) walls, we are trying to stick to lime for breathability. I know less chance of condensation issues with a party wall so I assume this is OK.
    • CommentAuthorrevor
    • CommentTimeNov 7th 2021
    How far up have you gone with removing the breast I presume you mean what you say and don't mean the fire place. Removing a chimney breast removes part of the structural integrity of the wall and particularly so with it being a party wall. Before you can do structural changes to a party wall you need to have a party wall agreement and a survey I guess to confirm that is is possible to do what you have done but is probable then some structural support is needed for the rest of the chimney.
    • CommentAuthorMike1
    • CommentTimeNov 7th 2021
    I've done similar to John in the past, except adding SBR to the splatter coat as a sealer - though that will also stop breathability, and may not be entirely resistant to the all the chemicals in with the soot.
    • CommentAuthorluz13827
    • CommentTimeNov 7th 2021
    @revor, thanks - there is already a party wall award in place and structural beams to support
    @Mike1, is breathability important in a party wall?
    • CommentAuthorrevor
    • CommentTimeNov 7th 2021
    Posted By: luz13827@revor, thanks - there is already a party wall award in place and structural beams to support

    That is great:bigsmile:
    • CommentAuthorMike1
    • CommentTimeNov 7th 2021 edited
    Posted By: luz13827@Mike1, is breathability important in a party wall?

    If you have a functioning damp proof course (or are on an upper floor), then no.
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