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Build Over Agreement Help Needed

Discussion in 'Building Regulations and Planning Permission' started by deemi786, 25 Jul 2020.

  1. deemi786

    deemi786

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    Hi all,

    Wondering if someone can advise me, please? My architect is stuck in Spain (don't ask) and is unable to help at the moment.

    We currently have a conservatory to the rear of the property. The plan is to demolish it and replace it with a rear extension that covers the whole of the rear property.

    Plans are approved. I received a letter from TW stating that "the council has told us you're getting work done and you have sewers near your property so tell us what you are doing".

    My question is, do I need a build over agreement? I assume I do as I know there are 2 manhole covers in the back garden that the extension would be built over.

    If I do, would I be able to do a self-assessment or would this need an approved build over agreement? Also, does anyone, in their expert opinion, see any reason as to why we wouldn't get an agreement from TW, looks pretty standard to me, but what do I know.

    I have also contacted TW for guidance and am waiting to hear back.

    Plans have been provided below, would appreciate any comments, etc.

    EXISTING_PLANS_AND_ELEVATIONS-742397.jpg new plans1.jpg
     
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  3. SpecialK

    SpecialK

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    Send the plans to TW and see what they say? I cant imagine them letting you remove/build over that manhole on the corner junction without it being moved?
     
  4. ^woody^

    ^woody^

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    You won't be permitted to have internal manholes.

    Permission will be based on the depth and diameter of the sewer pipes and how you plan to bridge over them.

    Why didn't your architect notice this and sort it out right at the start? If you don't get permission then you've wasted a lot of time and money.
     
  5. Notch7

    Notch7

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    You need a build over agreement.

    You will need to provide drawings and spec of your proposed new drainage layout.
    They may want a before and after CCTV of the public sewer part.

    TW are pretty helpful, but they are difficult to get hold of.

    I can't quite read the dawg but it looks like invert level is 1.8m in which case your foundation can't be only 1.2m as specified.
     
  6. DevilDamo

    DevilDamo

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    The self-certification process is handy but only for minor and less complex build over’s. Although bridging over the existing sewers should not be an issue, the formation of a new (adoptable) manhole on the sewer would require formal Build Over approval.

    To accompany the BOA will require various drawings and details. You would need some advice from your architect or somebody who is familiar with the process. Can your architect recommend somebody to assist during their absence?
     
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  7. deemi786

    deemi786

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    [
    Fair enough. I managed to get hold of him, he said he would ring tomorrow and discuss any questions I have. Not sure how a layman like myself could answer all of the questions in the application. Hopefully it's all straight forward and everything gets approved.
     
  8. deemi786

    deemi786

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    Apologies could you elaborate, do the foundations need to be deeper than the existing invert?
     
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  10. Notch7

    Notch7

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    Yes, to ensure foundation do not put pressure on drains its standard to have bottom of founds 150mm below invert level.
     
  11. Notch7

    Notch7

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    If you contact TW they will pass your enquiry to an engineer who will contact you by email or phone within a few days. I've found them pretty helpful, they will advise on which application you need and what other things they want as well as costs.

    I think on their site you need to follow the links for the developer section to get to the downloads.

    You would be able to complete the application, but you prob won't be able to provide drawings and a spec.

    The application will require a copy of the building regs drawings too.
     
  12. deemi786

    deemi786

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    The invert level on the diagram says 1.2m ( the one that's labelled foul m.h). The drawings say trench fill conc foundations depth to 1.2 minimum so they would need to lower (1.35m)?
     
  13. DevilDamo

    DevilDamo

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    Foundations should be taken down to ‘at least’ the invert level of any adjacent drains, so 1.2m would be ok and acceptable to Building Control. Depths should also take into account any nearby trees.

    Edit: Although saying that, we’ve had BCO’s accept to at least the same level and below. Think it may be up to the discretion of the BCO.
     
    Last edited: 26 Jul 2020
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  14. deemi786

    deemi786

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    Thanks, the architect just said the same thing and said he would help with the application but he sees no issues with an agreement being given.
     
  15. Notch7

    Notch7

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    Apologies, it should be at least as deep as, not 150mm below. See devildamo's post
     
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