Build Over Agreement Drawings & Plans

If you are building an extension or development near a public sewer, the water authority may require a Build Over Agreement before construction can proceed. We prepare clear and compliant Build Over Agreement drawings and plans for Thames Water, Southern Water and other UK water authorities, helping homeowners and developers secure approval quickly and avoid delays.
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When Might Need a Build Over Agreement?

  • Building an extension over a sewer
  • Building within 3 metres of a sewer
  • Loft conversions affecting drainage
  • Developments with existing public sewers

A Build Over Agreement is typically required when building work takes place above or close to a public sewer. Water authorities require drawings to ensure the sewer remains accessible, protected and structurally sound.

Discuss your project

Thames Water Build Over Agreements

Thames Water often requires a Build Over Agreement where building work is proposed above or close to a public sewer. This commonly applies to house extensions, loft conversions and small developments across Surrey and the surrounding areas.

As part of the application, Thames Water normally requires drawings showing the location of the sewer in relation to the proposed building works. These plans help ensure the sewer remains protected and accessible for future maintenance.

We prepare clear Build Over Agreement drawings and plans suitable for Thames Water submissions, helping homeowners and developers progress their projects smoothly and avoid unnecessary delays.
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Southern Water Build Over Agreements

Southern Water may require a Build Over Agreement when building work is planned above or within close proximity to a public sewer. This often applies to extensions, property conversions and residential developments where existing drainage infrastructure runs beneath or near the property.

Applications usually require clear plans illustrating the relationship between the proposed structure and the existing sewer. These drawings help ensure the sewer network remains protected while allowing construction to proceed safely.

We produce Build Over Agreement drawings suitable for Southern Water applications, ensuring plans are clear, compliant and ready for submission.
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The “small print”…

Just Plans is a Limited Company Companies House reference 10113657

By “advice” or “consultancy”, we mean that we are generally happy to offer provisional thoughts and suggestions to homeowners and other existing or potential clients, based on our experience of having submitted hundreds of planning applications for many different properties for many different councils over more than a 20 year period.
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Because of this and other similar experience, many people who are considering a project find it useful to talk us through their plans. At our reasonable discretion, we are generally happy to spend some unpaid time listening and walking people through the general process and the typical different options that they might like to consider.

Any such advice or consultancy is limited to provisional and general guidance. The risks and rewards associated with any project or decision exclusively remain the homeowner’s or the developer’s, unless we have explicitly stated otherwise in writing and have been paid to share in such risk or such responsibility.

Likewise, we assume no liability for taking on any “due diligence”, any CIL negotiation, or accurately predicting the Local Authority’s decisions, and which includes those pertaining to lawful development certificates.  
Unless explicitly stated otherwise in writing, and unless we have received payment for the same, we do not agree to act as Principal Designer, or as any Dutyholder, or similar, whether or not it forms part of RIBA or RICS or any similar legislation.
Unless otherwise agreed in writing, we always act exclusively as our clients’ agents, and under their authority. We agree jobs on a case by case basis, always evidenced in writing, and never on a merely verbal basis.

Footnote 1.
Re CGIs and imagery
The images contained within our website typically use a combination of photographs and drawing software. CGIs may not be identical to the as-built layouts.

For full terms of service and for how our plans should be used, refer also to the right hand margin of any plan supplied.
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