Problem inside my roof gable wall (now with better video)

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  • stator
    stator Posts: 7,441
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    stuart45 wrote: »
    I think the steel goes around the building as a band, so it's not just over the windows.
    This part of the gable end wall is in the loft, so it can't go all the way around. If it's horizontal, then it has to end within the triangular top of the gable end wall
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  • stuart45
    stuart45 Posts: 3,923
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    BRE have published reports on most of the none trad houses built after the war, so it may be worth getting hold of one of these. They will explain in detail the methods of construction and problems and remedial work required.
  • stator
    stator Posts: 7,441
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    stuart45 wrote: »
    BRE have published reports on most of the none trad houses built after the war, so it may be worth getting hold of one of these. They will explain in detail the methods of construction and problems and remedial work required.
    That was a good idea, I've got myself a copy of BR130 but unfortunately it doesn't give any diagrams of the top of the gable end wall, the triangular bit in the roof. It shows the reinforcement above and below the windows and doesn't mention any anywhere else.
    I'm glad I know that the internal wall is the load bearing wall though, so the damage to the outer wall won't make my roof collapse :)
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  • stator
    stator Posts: 7,441
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    edited 17 December 2018 at 9:53PM
    Made another video, it's a bit better.

    *deleted crap videos, see further down for decent quality video
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  • stuart45
    stuart45 Posts: 3,923
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    When concrete spalls, it is often when the rebar rusts, so it may be the case in your house. The main issue for you is that the pieces of concrete in the cavity could be diverting any moisture on to the inner skin and down to your back door.
  • EachPenny
    EachPenny Posts: 12,239
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    stator wrote: »
    Made another video, it's a bit better.
    I'm not sure it adds much to your search for information, but the spots of light in the second video interested me... these look like the kind of 'sparkles' you get from light relected by mineral deposits in caves or in some kinds of rock specimens.

    I've watched thousands of hours of CCTV of the inside of sewers, but have little experiece at looking at concrete like this, so don't know if what I'm seeing is unusual or significiant... but I'd certainly keep in mind the possibility that the aggregate used in the concrete is causing some kind of damage (spalling?) as a result of mineral crystal growth.

    Concrete itself relies on chemical reations which form a crystalline structure which binds the aggregates together. Those reactions and the crystals formed can be affected by factors such as the water/cement ratio of the mix, and also contamination. If you want to take this thought process further then it would be worth doing some research on Sulphate Attack and also the formation of Ettringite.

    I'm not saying this is certainly the cause of your problems, but to me those 'sparkles' don't look like something I'd expect to see and I would want to know whether they are significant.
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  • stator
    stator Posts: 7,441
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    edited 17 December 2018 at 8:46PM
    Well my new endoscope arrived very quickly, and now I have some better quality video

    Skip the middle of this one, but definitely see the end from 3:30, there's an unexpected item embedded in the wall (or it might be the end of a rebar)




    And if you're bored take a look at all this crap in the cavity wall (this is from a different hole)

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  • stuart45
    stuart45 Posts: 3,923
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    When they used to cast insitu lintels, the rebar often had a hook at each end when it was placed into the concrete, bit like the one in the video. Rubbish often gets slung into the concrete.
  • teneighty
    teneighty Posts: 1,347 Forumite
    That is much clearer, what borescope brand was that filmed with?

    So it certainly looks like corroded reinforcement has caused the concrete to the outer leaf to spall in cavity. The good news is it looks like it isn't the main structural ring beam. Possibly just some starter bars to link the first floor lift with the gable lift.

    I wouldn't lose any sleep over it.
  • stator
    stator Posts: 7,441
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    edited 18 December 2018 at 1:17AM
    teneighty wrote: »
    That is much clearer, what borescope brand was that filmed with?
    It's this potensic model. Despite the specification, I've only managed to get it recording video at 1280x720, by default it records at 640x480. I think it can take pictures at 1600 x 1200

    https://www.amazon.co.uk/gp/product/B01EWO99CY/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1


    If anyone wants to see how Laing Easi-form houses were made back in the day:
    https://youtu.be/OPXiRRcAeaE?t=348
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