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1st floor hearth showing in ground floor ceiling

Discussion in 'Building' started by davidc123, 8 Aug 2021.

  1. davidc123

    davidc123

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    I moved into a 1930's house in April and was curious about a rectangle shape showing in the dining room ceiling. I noticed on the original plans that there used to be a chimney breast there so I pulled up the carpet in the bedroom and found a large concrete hearth base.

    I pulled up some nearby floorboards to try figure out the depth but the base extends further under the nearby boards, and the other side is covered by a noggin the same height as the joists.

    I've read that these things are supposed to be poured into a frame that is built until the joists and shouldn't be too deep, but if that was the case I don't understand why the rectangle shape is showing in the ceiling below.

    It's all solid when tapped from below, which i wouldn't expect if it was poured into a timber frame from above, so I'm a bit worried that it's actually one massive concrete block that is sinking into the ceiling and might drop. Can anyone see any other explanation for it?
     

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  3. catlad

    catlad

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    I would be a bit concerned too. I think I would remove it, if it now served no purpose.
     
    Last edited: 8 Aug 2021
  4. tony1851

    tony1851

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    At the same time they removed the ground floor chimney breast, they've also removed the whole wall (was it an internal chimney?). Consequently, they've had to remove the upstairs chimney breast as well, otherwise there would be an imbalance and the weight of the breast above would tend to rotate about the steel beam and tilt slightly downwards.

    I suspect what you are seeing in the dining room ceiling is the remains of the upstairs brick chimney breast, rather than the projecting hearth itself. The hearth is probably further out into the bedroom, supported off trimmer joists.

    On the other hand, I might be barking up the wrong tree. Or just barking...........
     
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  5. davidc123

    davidc123

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    Yes it was an internal chimney but I'm not sure whether it extended to the ground floor. There is original parquet floor under the carpet below it, and the plans of the work don't show a chimney breast. They do show something on the other side of the removed wall which possibly could have been a fireplace in the kitchen (see attached). The shape in the ceiling also has the same dimensions as where i think the concrete extends to upstairs.

    Ideally I'd just remove it but if it is a massive lump of concrete I'm guessing it's going to be a very difficult job.
     

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  6. davidc123

    davidc123

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    If it is the bottom of the upstairs chimney breast and it never extended into the dining room then that would explain why there are no hollow sounding parts to it. But I still have the same worry about how it's being supported and whether it's a danger.
     
  7. oldbutnotdead

    oldbutnotdead

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    It shouldn't be a major pain to shift that slab, if you're lucky you'll find its is mortar not concrete and will respond well to stitch drilling and a bit of SDS chiselling. You may find it continues into the wall- again, stitch drilling will separate it nicely. If the ceiling below is lath and plaster you may get a bit of cracking when you attack the thing but risk of collapse is low (laths are surprisingly strong).
     
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  8. davidc123

    davidc123

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    The top layer that is flush with the floorboards is mortar but below that it's concrete - you can make out the stone in the section under the lifted floorboard in the first photo. Maybe there's more mortar below that though.

    If I was to stitch drill and chisel it I guess I would need to expose a side of it so that it has some space to break into, but I think I can only do that by trying to remove the noggin and I don't know if that is what's holding it up.
     
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