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Monitoring cracks in an old building

Discussion in 'Building' started by MisterBoy, 15 Jun 2020.

  1. MisterBoy

    MisterBoy

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    I've lived in a detached 1860-ish house just over 3 years. Every now and then I notice a crack in external wall or on a ceiling that I can't tell if it was there before or not - being an old house there are a lot of old cracks and often I think it's the way the light catches it or whatever.

    None are wide - hairline cracks in ceilings, not much wider outside - but there's at least one quite long one down an external brick wall (but no sign on the inside). Half the house is rendered and cracks there seem to be horizontal/vertical which makes me think that might just be like cracks in a skimmed wall?

    I was looking into tell-tales like: https://www.surveyorsequipment.co.uk/inspection-detection/crack-monitoring/standard-tell-tale.html

    But they seem to have a resolution of about 1mm, maybe half a mil. If the existing cracks got 1mm wider it would be pretty obvious so does that suggest it's not worth putting the monitors on? Any expansion seems more like a tenth of a mm. Or is it worth putting a few on anyway for peace of mind, they don't cost much?

    The other idea I had was since the house is rendered/painted white (about 10 years ago), cracks show up reasonably well. Would taking a really detailed photographic record be worthwhile so I can tell if a newly-seen crack is actually new?

    Thanks for any advice.
     
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  3. Bobby Dazzler

    Bobby Dazzler

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    The method used to be to fix thin pieces of glass across the cracks.
    I'm not sure if that is the more modern method.
    I think you would need some pretty strong glue to fix glass across the cracks.
    Also, I assume you need to determine the potential direction of movement to monitor any movement.
     
  4. Rekusu

    Rekusu

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    X years ago, we had some cracks on our first floor maisonette. Transpired it was caused by the neighbouring very tall Cyprus trees being too close to the building. The entry porch was kinds hanging on by the grace of God.

    However, the insurers monitored the cracking after the trees had been removed. They hammered small, special nails into the wall, either side of the crack in a number of locations. These 'nails' had indents in the centre and they just used a Vernier calliper (https://www.ebay.co.uk/itm/LCD-Digi...702283?hash=item594e986fcb:g:zToAAOSwwxRez4vw) to measure every month for a year and kept the recoded. Easy peasy!
     
  5. ^woody^

    ^woody^

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    You would want a crack to be more than 3mm and getting wider before you could monitor it. You are not interested in the crack width, but which part of the wall is moving and which way. And the thing is buildings move seasonally so cracks often occur and close up over the course of several seasons. And you don't want to be monitoring several cracks. Normally just one.
     
  6. ^woody^

    ^woody^

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    That's a waste of time as of the glass breaks all that says is that there was movement of some sort, but you won't know when, how, which way, how much etc.
     
  7. oldbutnotdead

    oldbutnotdead

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    Sure you can still get crack gauges- yes you can, just Googled them. 2 bits of glass, 1 with an x, the other with grid lines.
    Fit across the crack, record the position of the x weekly or monthly or whatever.
     
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