What Is A Build Over Agreement?
Share
Copy Link
Since 2011, most of the private sewers in the UK fell into public ownership, which means that build over agreements are required for any work being carried within 3 metres of a public sewer.
The process is actually fairly straightforward but an important consideration for many extensions and shouldn't be overlooked.
We answer your popular questions, including how you go about getting one and what a build over agreement will cost.
If you are thinking about a renovation project in the near future and need some help with where to start with your project, try our renovation advice session.
Renovation Advice Session
What is a build over agreement?
If you are doing any building work within 3 metres or over a public sewer, it's important that you let your local water supplier know and obtain a build over agreement.
A build over agreement is a legal document which is there to protect the public sewer which you are intending to carry out work near to or over.
The build over agreement gives your local water supplier assurance that they will be able to access the sewers in the event of a blockage or issue in the future. It also gives the water supplier the guarantee that any weight of your new extension will not damage the public sewer.
Any access chambers will need to be moved and not built over. You can build over pipes but you will need to ensure there is adequate support to ensure that the sewage doesn't collapse.
How do I get a build over agreement?
You will need to apply to your local water supplier to obtain a build over agreement. With the need for build over agreements being in place since 2011, the process is a very standard and normally a straightforward one for the water supplier.
The documentation required will include scale drawings of your original house and the current drainage, the planned extension and changes to the drainage and a site location plan which shows your home in relation to rest of the street. If you are building over the sewer or within 1.5 metres, you will also need a cross sectional drawing which will show how your plan to build over the sewage pipes.
The application is fairly technical so it's best to leave it to your architect to submit on your behalf.
How do I know if I need a build over agreement?
A manhole in your garden is an indication that you will need a build over agreement; you won't be able to bury it under the new extension but you will have to move it instead.
A drainage survey before you carry out an extension is always a good idea, this will confirm how close you are to the public sewer and also if the weight of your extension will cause issues to the existing drains.
When you submit your plans to your local authority, they will also notify the water supplier who will be in touch if you are near the public sewer. They will state that they have been notified that you are building over or within 3 metres of a public sewer and request that you submit an application in order for them to make an assessment.
When in the process of your renovation do I get a build over agreement?
This can be done once you have your planning application approved and have the structural drawings finalised.
You should not start any building work until you have your build over agreement.
How long does it take to get a build over agreement?
You should expect a build over agreement to take around 21 days from when you submit your application to getting approval from your local water supplier.
Depending on your water supplier, the process may take longer. Water suppliers such as Thames Water are well versed with applications and it should be a straightforward process, assuming you submit the correct paperwork.
How much does a build over agreement cost?
The cost of the application for a build over agreement will vary depending on your water supplier, with Thames Water charging £299 for online applications.
You may have carried out a drain survey when purchasing your property. You should expect to pay around £100 - £200 for one if you need it.
There may be additional building work required such as moving the manhole cover or adding a concrete lintel for support.
If you are instructing your architect to apply for a build over agreement on your behalf, expect to pay them for the time.
What if there is no build over agreement?
It is unlikely that this building control inspector will sign off the work if you don't have a build over agreement in place. You are able to get a retrospective build over agreement where your local water supplier may come and inspect the work.
If the weight of the extension damages the sewer and your water supplier can't access it, you may have to demolish the structure if there is a major issue - although this is an unlikely event.
If you are purchasing a house which has had an extension carried out without a build over agreement, you can take out an indemnity insurance. Your solicitor should advise you on this prior to purchasing the house.
Sign up with Facebook
Sign up with Google
