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Foundation back fill... soakaway?

Discussion in 'Building' started by i_am_fubar, 2 Aug 2021.

  1. i_am_fubar

    i_am_fubar

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    I've been excavating for a new patio that isn't flush with the DPC and have found that the foundation trench of our extension is back filled with old bricks and it *looks* like it may be designed as a soakaway.

    The foundation blocks are not mortared on their vertical edges and the cavity does not have a tray that spans both skins (But we do have an inter-skin hydro-wick aka cavity wall insulation)

    Is this a 'normal' building strategy to drain the cavity below grade and I need to make sure I keep the soakaway integrity?

    Or, more likely, were these a bunch of cowboy builders who just dumped their old bricks and mortar into the trench because it was easier and I should just pile soil down there as I expose it?

    Cheers :)
     
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  3. Mr Chibs

    Mr Chibs

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    Think we need some photos please.
     
  4. Notch7

    Notch7

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    is this a new extension underway?

    is it a strip foundation with foundation blocks below ground or a mass filled concrete foundation with just one blockwork course and a few brick courses below DPC
     
  5. jeds

    jeds

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    I'm not really sure what you are asking. Are you trying to resolve a dampness issue?
     
  6. i_am_fubar

    i_am_fubar

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    So, on the left of this image, behind the spade and fork where I've busted through the concrete and shoved some geo-fabric to stop soil falling down is the area in question. Will get a picture of the actual gap tonight (if I can)

    [​IMG]

    Once I took up the concrete slab/patio/path thing, I found that the area between the foundation blocks and the edge of the foundation excavations (~6-9 inches) just filled with building rubble.

    I've exposed at least two foundation blocks so it's a strip foundation.

    We have damp issues elsewhere, but I don't think it's related to this. I just don't want to cause one by naively assuming the construction method.

    Basically, my gut is saying that the foundations were back-filled with rubble as an easier/cheaper way of getting rid of the rubble and that I should be ok to just level the soil over the top. But part of me worries there may be a reason why you would back-fill with 'free-draining aggregate' (aka bricks)?
     
  7. Notch7

    Notch7

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    I think you’ve just exposed a load of builders crap.


    I guess you mean the foundation trench was back filled with builders rubble and are concerned it may be channelling water down to the ground around the strip foundation.

    I can’t see that being much reason for concern.
     
  8. i_am_fubar

    i_am_fubar

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    - Figured that was the case... Damn messy builders.

    - Oh, it most definitely IS channelling water down into the foundation trench (especially now I've removed the concrete pathway). I just don't know if it's best to:

    A) Try and keep as much muck out as possible to allow the channelling of water to continue.

    or

    B) Fill that bad boy up with whatever I have around and pretend I never saw it.

    or

    C) Clear it out and back-fill with a 'proper' back fill material, whatever that may be.
     
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