Terms and conditions

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Build over a public sewer – self-certification

Acceptance of our terms

You confirm that to the best of your knowledge, the information you have given is correct and complete and meets our criteria as set out below.

If the householder or the local authority’s building control department requests a survey or inspection, you will need to submit a full application. We will carry out the survey/inspection following advance payment of our costs.

We will not be liable for damage to any part of your building or premises as a result of the presence of the sewer.

You agree to indemnify us against all costs incurred as a result of any damage to our sewer caused by your work and/or the presence of the building you erect.

If, without our consent, you change your building work from that described in your answers to our online questionnaire, the self-certified build over agreement becomes invalid and you agree to indemnify us against all costs incurred in maintaining the sewer which would not have been incurred but for your works.

Our consent to your proposed work is subject to any conditions that may be imposed through the planning or building regulations process.

You agree to check and verify the depth and position of the sewer before you start work on site.

Criteria for self-certification

1. The proposed building must be for domestic purposes only and an attached single- or double-storey extension, conservatory, annex or garage.

2. The proposed building must be attached to an existing property.

3. You must not build a new detached domestic property over the sewer.

4. You must not make any alterations or new connections to the sewer. If a new connection is required, this must be subject to a separate application.

5. You must not construct any structures above, or enclosing, manholes on the public sewer, even when they have double-sealed bolt down covers.

6. Your foundations must be at least 500mm from the outside of any manholes located outside the property.

7. The building foundations must be strip or trench-fill only.

8. The sewer must be no more than two metres below ground.

9. The sewer must be no more than 160mm in diameter.

10. The sewer must be made of either clay or plastic.

11. The sewer must not change direction, size or gradient beneath the proposed building.

12. The sewer must be at least 500mm from foundations which run parallel to it.

13. The sewer must have at least 150mm of granular surround where it crosses through walls.

14. The proposed building must not transmit any additional loads to the sewer.

15. The foundations must extend at least 150mm below the underside of the sewer

16. The internal floor slab must be at least 300mm above the top of the sewer.

17. The sewer must always be accessible via your land or your next-door neighbour’s.

18. You are not aware of any problems such as blockages, flooding, or smells emanating from the sewer.

19. You have traced the sewer and checked that it is in a serviceable condition. Please note that sewers of this type occasionally have minor defects such as misaligned joints (often since new) or minor cracking. We accept such pipes as being in a serviceable condition.