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Do I need to get the builder back out for this crack in external wall?

Discussion in 'Building' started by GR87, 17 Mar 2019.

  1. GR87

    GR87

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    Hi all. Looking for a bit of advice please. My wife and I had a ~4m RSJ installed under this wall approx 12 months ago. All spec’d by SE, signed off by BC etc. I have never noticed before but over the weekend I noticed what appears to be a small diagonal crack approximately 5ft above where it was installed (see photo). My wife and her old fella who’ve lived through a couple of construction projects are adamant it’s a settling crack and nothing to worry about. But if they’re chilled out then I’m on the other end of the spectrum. You guy’s live an breath this stuff, anything to be worried about? Thanks.
     

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  3. tony1851

    tony1851

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    Can't tell from the pic. You need to post a few more pics showing not just the crack but the surrounding context to get any meaningful responses.
     
  4. GR87

    GR87

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    Thanks @tony1851 for the reply. The furthest back I stood when I took a pic was the one attached. I’ve now put a silicon over it just to protect it from the elements so you can’t even really see it but I can scrub that off and take more pictures if need be.

    This picture was taken midway through the project (~8 months ago). The RSJ’s were in at this point but any crack is potentially unclear as the image isn’t as focused due to standing so far back.

    Father-in-law and better half adamant a little movement is to be expected since the back wall of 50 year old house was removed but always keen for a third opinion. Cheers.
     
    Last edited: 18 Mar 2019
  5. ^woody^

    ^woody^

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    There should be no such thing as settlement after a beam installation.
    But the difficulty is proving that the crack relates to the building work.

    Either way, there is cracked render that will let in water, and it needs dealing with.
     
  6. KenGMac

    KenGMac

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    GR87, good evening.

    Am I correct in saying the crack does not reach the window opening? In the posted image [first one posted]

    Next? there does not appear to be any other cracks on the elevation, especially at or near the lower right hand sill of the window ?

    Are there any indications anywhere internally of any crack distress occurring? areas such as wall to ceiling / at Skirting to wall, or in the corner of the upper room between the rear and gable elevations?

    Is the dark rectangular blanking plate with the crack running over the top of it covering an old vent?

    Ken
     
  7. GR87

    GR87

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    Thank you for taking the time tonreply @^woody^, appreciate it. I’ve read on here that there can be a flex or an allowable movement with RSJ’s. Is that just people talking BS?

    @KenGMac, I’ll take each of your questions in turn mate.

    No, the crack does not reach the window opening.

    No, I cannot / did not notice any other cracks in the elevation.

    Yes, there are a couple of small plaster cracks internally where the walls and ceilings meet. Just for context, we had ~80% of the house skimmed but some walls did not need skimmed so I sanded these. Where the cracks generally appear (in other rooms too) are mostly where new plaster skim and old mortar walls meet where no scrim tape was used. I’ve uploaded an image of the internal too. Not there is a small crack in the area of the vent but it doesn’t align with the one outside.

    It’s an old vent. Cheers!
     
    Last edited: 18 Mar 2019
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  9. GR87

    GR87

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    Thanks all for the replies. I did the 'tap test' to check for a hollow sound and I couldn't hear any difference across the entire area. However, I think I’ll get him back out for peace of mind if nothing else.
     
    Last edited: 18 Mar 2019
  10. ^woody^

    ^woody^

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    When a beam is loaded retrospectively as in this case, it will flex a little (deflect) as the load is applied when the props are removed. This is worked out by the designer so that it does not deflect so much as to crack walls and finishes. This is not a problem when it's new build.

    Then when builders prop the wall, a commom error is to actually jack the wall up which can cause cracking, or not pack it properly which can also allow movement and cracking.

    So in any investigation, the calcualtions for the beam would need to be recehecked to ensure that loadings and assumptions are correct, and then the methodology of the install would need to be ascertained to determine if it is a install/quality issue.
     
  11. tony1851

    tony1851

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    The calculations may only show a live-load check rather than a total live + dead load check, as the design codes usually only stipulate a limit for live load deflection.
    Dead load deflection (ie the bend caused by the structure above the beam) is not stipulated and is usually left to the judgment of the SE.

    If the crack is a structural issue (only a surveyor on site would be able to check) my feeling is that it might be caused by slight settlement of the wall supporting the beam; with a steel beam, the deflection under dead load would have occurred immediately after installation, not 12 months later.
     
  12. KenGMac

    KenGMac

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    GR87, good evening again.

    On board with Woody and tony above.

    As far as the "main" newest appearing external crack, because it does not run into the window reveal [an Ingoe up here?] that would tend to indicate that there is / has been a very, very slight movement, but not a massive movement. if there were to have been a serious movement then the external crack should run right into the window AND there would "probably" be a further crack [which there is not] from the right hand side of the window sill in a diagonal direction towards the new steel lintel. in effect the latter would indicate a drop of a large section of the external leaf of brick.

    Internally OK there are a few hairline cracks that can / do / Will occur in a skimmed wall, but nothing of any significance to indicate a serious or on-going failure.

    Your external treatment with Silicone will stop rain water entering behind the roughcast render, problem there is that the mastic will require to be re-applied every now and then.

    Ken
     
  13. GR87

    GR87

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    @KenGMac and others, thanks all for your replies. Appreciate it. I will keep a close eye on it. The DIYer adventurer in me is tempted to chip away a few inches of roughcast and inspect the brickwork; ever friend and family member is telling me to leave it and keep an eye on it. I think I’ll listen to them. Builder came out and did the ‘tap test’ with no difference in sound anywhere on the wall. He said it’s sealed now and that he’d periodically check the seal for any sign of gaps where water could get in so I think that’s the play here. Thanks guy’s.
     
  14. KenGMac

    KenGMac

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    GR87, Hi again.

    I sometimes use a very, very thin length of wire to attempt to determine if the crack is only in the roughcast or right into the bricks or block work?

    OK by no means the most accurate of tests but can assist?

    Ken
     
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