Do I need a build over agreement for an extension above or near a mains sewer pipe?

You’ll need to apply to your local utilities provider for a build over agreement if:

  • You’re building within three metres of a pipe serving just one other property – known as a lateral drain.
  • You’re building within three metres of a pipe serving more than one property – known as a public sewer.

A structural engineer will be able to design your foundations so that there is no additional load placed on the sewer. The engineer will also prepare the relevant drawings for the build over agreement. Once you have agreed the build over agreement, you can proceed with obtaining planning permission.

Building control will need to inspect the work has been carried out around the sewer in accordance with the sewer companies requirements. They would also check the work conforms with the approved foundation design.