Everything You Need to Know About Build-Over Drainage Surveys

proposed elevation requiring a build-over drainage survey

For many of us, building an extension or working on our home is an exciting time. Adding a new room or enhancing an existing space can be extremely rewarding but it isn’t without its challenges.  

This is particularly true if you’re building on top of, or close to,  a public sewer or drainage system. If this is the case, you’ll likely require a build-over drain survey to keep your project on track.

Our team at Express Drainage Surveys are experts in all types of drainage systems and CCTV surveys and have put together this handy guide to inform you of everything you need to know on the topic.

What is a Build-Over Agreement and Drain Survey? 

If you’re intending on building an extension or addition to your property, there is plenty you’ll need to consider. As well as the usual planning permission legislation that may come with this kind of build, carrying out works above or close to a public sewer or main drain may mean you require a build-over agreement. 

Simply put, a build-over agreement is a legal document that protects sewers and drains from any damage or disruption that may be caused as a result of the construction. They also allow water companies to access these areas if they ever need to be cleaned or repaired. 

Getting a build-over agreement protects both you and the water company- and should minimise the risk of any damage being caused.   

In order to obtain a build-over agreement, a CCTV drainage survey will often be carried out to ensure drains will not be restricted, or worse, at risk of being collapsed on by work above. 

Before any work begins it’s important to ensure all guidelines and relevant legislation is being adhered to. Build-over agreements can be applied for via your local water company’s website. 

Can I Use the Self-Certification Declaration?

Sometimes a build-over agreement may not be necessary. Instead, you can get a self-certification declaration. This certification will only be permitted if the affected pipes are less than 150mm in diameter.

If this is the case for you then you may be presented with an automatic self-certification, declaration meaning you can begin work without needing a build-over agreement. 

You’ll also be required to provide some further information on the pipes, including the material they’re made from, the condition they’re in and what safety provisions you’ll put in place.   

When Do I Need a Build-Over Drain Survey?

proposed house extension requiring a build-over drainage survey

Before you’re awarded with a build-over agreement to give your work the green light, a build-over drain survey will be required to confirm your eligibility. 

A fairly simple process, you’ll be required to submit an overview of your project to the local water authority explaining what you’re planning to achieve. Accompanying this submission should be a pre-conditional survey which will take an in-depth look at the present drainage layout, identifying any existing issues that may need addressing. Specifically, a CCTV survey will focus on the structural integrity of pipes, their location and how the water is flowing. 

It is also worthwhile to undertake a post-conditional survey once you’ve completed your work. Another CCTV survey will ensure work has been carried out correctly and has not adversely affected the public sewer or drainage system.     

You will not need to apply for a build-over agreement if your planned works are more than 3m away from the nearest public sewer or drainage system. Plus, if all of the drains on your property are private, then you will not require any special planning permissions. 

What Are the Build-Over Restrictions?

There are some restrictions that may prevent a build-over agreement from being awarded. 

These include:

  • If the sewer is pressurised 
  • If it is a strategic sewer that carries waste to a number of properties 
  • If a brand new building has been proposed (local water authorities may advise that sewers are diverted)  
  • If manhole covers or drain lids will be located within a building because of the work 

Once you’ve been awarded with a build-over agreement, there may be restrictions that you need to follow which will be outlined by your local water authority. This may include paying for materials and repairs if they’ve been identified in a post-conditional survey.    

What are the Benefits of a Build-Over Drain Survey?  

As well as acting as a tool to earn you a build-over agreement, a build-over drain survey can bring a range of other benefits. 

This includes helping to confirm all of your drains are in good, working order prior to work beginning, ensuring that all drainage is fully functional and that all drain systems are in the correct location. 

Additionally, if you’re in the process of selling your property, then a CCTV drain survey can reassure potential buyers that the drains do not need to be a cause of concern. 

Here at Express Drainage Surveys, we can offer a whole host of domestic and commercial services, helping get your drains up to scratch. For more information about what we can offer, contact us today.