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Holes drilled into joists outside permitted zone

Discussion in 'Building' started by r_c, 27 Aug 2016.

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  1. r_c

    r_c

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    I have concerns about all the holes that have been drilled into the joists in our new extension. My understanding from documents like this (North Herts Council Building Control Technical Guidance Note No. 22 Notching Of Joists) is that holes should be:
    1. Drilled into center line.
    2. Drilled between 0.25 - 0.4 the length of the span.
    3. The distance between holes should be greater than 3 x hole diameter.
    4. Hole diameters should be 0.25 x joist depth.

    The holes in my joists are not within the permitted area. In the photos below, I have use red tape to mark 0.25 and 0.4 the span. There is one hole right in the center of the span, with a cable hanging down out of it (this has 3 joist together).

    Why have they drilled holes outside of the permitted zone? The document is from building control - it must carry some weight?


    Joists: 218mm x 45mm
    Span: 4060mm (from edge of RSJ to edge of wall bracket holding joist)
     
  2. big-all

    big-all

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    the regs are safety orientated
    pick a number call it the breaking point
    double the timber size call that the springy floor
    then add a further 30% to allow for holes and notches
    then add a further 30% to allow for wood defects
    in other words you have nothing to worry about
     
  3. tony1851

    tony1851

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    As above.......................relax, sit down and have a nice cup of tea and a chocolate digestive.
     
    Last edited: 27 Aug 2016
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  4. ^woody^

    ^woody^

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    On the whole, there's nothing to worry about
     
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  5. endecotp

    endecotp

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    I'm sure it's true that it's perfectly safe, but It doesn't reflect well on the builders who have done it; where else in the build have they been "flexible" in their interpretation of the rules?

    Were plans drawn showing where pipes would run?
     
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  6. ^woody^

    ^woody^

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    There is a certain skill in knowing what can be done safely and "non standard".

    Remember that the approved documents are for the lowest common denominator, and there are many many ways to build.

    But yes, at the other end of the scale, there is not the same skill in being just clueless.
     
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  7. r_c

    r_c

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    No. I was often surprised at the lack of detail in plans. I have learnt a valuable lesson, and now realise that the architects 'detailed plans' were nothing of the sort, and I should have persisted when I was told "don't worry about the details, these guys know what they are doing."


    I have heard a few times how everything is over specified in the UK. I'm still very frustrated that all these holes are outside the permitted zone. It's not like there are one or two of them outside - EVERY SINGLE BL***Y ONE is outside! :mad: And I don't see any reason for any of them being there - every hole could have easily been made in the 0.25 - 0.4 space. This is the new part of the house, and they could go anywhere. I think there are about 20 or so joists, and all but about 2 or 3 have holes drilled like this. A bit of me was hoping you'd tell me that he should replace all of them!

    Thank you again all for your comments.
     
  8. big-all

    big-all

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    the person who drilled will have drilled them where he needed to in a time served way where his journeyman who was taught by his journeyman are unaware this restriction exists or dismiss them as "i know best" way
    and guess what no floors have collapsed a few may be creaky with much greater "butchering" but non have collapsed
    you are talking the equivalent off 35 in a 30 zone no one will bat an eyelid no real danger at all just tinkering at the edges
     
    Last edited: 28 Aug 2016
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  9. ^woody^

    ^woody^

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    You don't get pipe or cable runs on drawings unless it's new build and you have a dedicated M&E design contractor.

    It's not possible for any runs to be ascertained when everything is already built
     
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  10. Echo the husky

    Echo the husky

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    It's incredible what can be got away with, having lifted floorboards and seen enormous wide and deep notches in the top of joists where plumbers have installed pipes, or where the joists have been peppered with holes for masses of cables.

    My cable holes would have all been in line though!
     
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