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Extension footings depth

Discussion in 'Building' started by an203888, 8 Dec 2019.

  1. johnny2007

    johnny2007

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    In my days of working in a team, we were called to many failed and cracked extensions.
    This usually was the result of refilling the fundations and poor concrete mix.
    Of course the cowboys would be nowhere to be seen.
    From memory between 1992 and 2003 we took down a dozen extensions and we were never called back to many others.
    I'm told that this practice is still in vogue with modern cowboys.
     
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  3. Leofric

    Leofric

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    :confused: What is this, surely you excavate the trenches and just pour the concrete foundations :?::!:
     
  4. johnny2007

    johnny2007

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    Yes, I would.
    But some cheapskate cowboys would give impossible cheap quotes and then do this sort of things to be on the money.
    I blame people who think they can have a kitchen extension done with £15k all in.
     
  5. Leofric

    Leofric

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    Yes but ,excuse my ignorance but what do they do apart from just pour concrete into the trench:?:
     
  6. an203888

    an203888

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    I will dig them out and then get BC to take a look, don't want them having a wasted journey!

    I don't understand how you can have plans to specify the depth. Untill you have started digging, how would you know?!!
     
  7. johnny2007

    johnny2007

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    They throw back in what they excavated and other rubbish.
     
  8. ^woody^

    ^woody^

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    Wtf?

    Every set of plans I see to approve must have a specified depth!

    How do you know? You instruct a competent designer not an idiot imbecile who does half a job.
     
  9. ^woody^

    ^woody^

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    That may be so, but surely 12 jobs in 11 years does not warrant the "many builders" statement to imply that it is routine and common.
     
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  11. johnny2007

    johnny2007

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    That's us, one small team.
    A dozen extensions is what we took down, we were called to price up repairs to probably double that number and never called back because we either refused to bodge a repair or were too expensive, so that makes it 36 roughly.
    How many other extensions have been built by the cowboys that we never came across?
    Just think about the hundreds of quotes we did and the very small percentage of jobs we actually did (maybe 10%).
    This is because in the London area neighbours don't talk, pubs don't exist anymore and so when people need a builder they go on the internet.
    So naturally there are cowboys taking advantage of this.
    They price an extension at £15k or even £10k and people get lured into the cowboys' spiral of failure.
    It's cheap for a reason.
    I'm sure everyone of us in the trade have been called to fix a job or completely redo it.
    There are plenty of cowboys out there and I think the number is rising because of the obsession with getting everything cheap.
     
  12. ^woody^

    ^woody^

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    Probably just the same family of gypo's working the estate. It's not common in the other 130,390 sqm of England.
     
  13. johnny2007

    johnny2007

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    You'd be surprised.
    In west london it's not the gypos, it's the non Steve and non Dave, coming from east of the world, past last country in Europe and well into the next continent.
     
  14. an203888

    an203888

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    Hey woody, thanks for the reply.

    As far as I'm aware the architect I have appointed isn't an idiot imbecile who does half a job. I know that my family have used him for at least the past 30 years and find him very good. How did plans get past BC without this must have info on it then? Please tell me how the "designer" is supposed to specify the depth? Have they already dug out all the footings and inspected the earth? I'm just curious? It makes no sense to me?

    Thanks
     
  15. johnny2007

    johnny2007

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    Every area has its own standard due to geological features.
    Then the architect should consider the site, i.e. trees nearby.
    Then in any case BC will inspect the excavation and approve the depth or not.
     
  16. noseall

    noseall

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    Many 'architects' just say either go with ground conditions or go with BC. It's a cop out and the architect is unlikely to leave his office and babysit you whilst you are perched on your digger either. It's a DIY'er thing.

    Dig down a minimum of 1m and assess the ground. If it has changed considerably from dark growing matter to sandy virgin earth (no old coke cans, scaffold clips or polythene) and it is below the existing concrete bottom, then you are likely to be on good ground.
     
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  17. paulrockliffe

    paulrockliffe

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    The local geological features mean very little when you're talking about digging into a patch of earth around 20sqm, especially as you already know the ground has been disturbed right next to where you want to dig. Round here BC don't allow you to dig at all until they've inspected so they can take account of nearby trees, then BC will tell you what they want as a result, but subject to them looking in the hole before the concrete is poured. Builders won't give a fixed priced for foundations beyond a price for 60cm x 1m, or whatever the usually get asked for by BC, subject to BC approval.

    So what value is being added by an architect specifying the foundation design prior to the dig? it doesn't matter how long the architect spends on site and how diligently they account for trees, local geology or anything else, as ultimately someone else will tell you what the foundations need to be regardless.

    There may be particular reasons why having a design done up front is necessary - how far do you dig before switching to piles or where trees make a normal foundation unacceptable - but for most simple extensions it is normal to specify a foundation width in terms of the thickness of the wall and a depth in terms of what BC will accept.
     
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