Two drainage engineers carrying out a CCTV drain inspection at a domestic property.
When planning a building project, it’s crucial to consider the potential impact on existing drainage systems. A build over drainage survey can provide vital information to help you make informed decisions and avoid costly mistakes.
In this article, we will explore the importance of these surveys, the risks of not having one, the benefits they offer, and how to ensure they are carried out correctly.

Why is a Build Over Survey Needed?

Building projects often involve significant investments of time and money, making it essential to consider every aspect of the project from the outset.
One critical aspect that can sometimes be overlooked is the impact that a new building may have on existing drainage systems.
A build over drainage survey can help identify any potential problems and enable you to make adjustments to your plans before work begins.
In this section, we will discuss what a build over drainage survey is and why it’s essential to include in your planning process.

What is a Build Over Drainage Survey?

A build over drainage survey is an examination of the existing drainage systems within an area that is planned for development or construction.
This type of mapping survey is designed to identify any potential issues or risks associated with building over or near existing drains, sewers, or other water management systems.
The survey typically involves the use of specialized equipment, including CCTV cameras and sonde devices, to inspect the interior of pipes and other underground structures.
It can also involve physical inspections of manholes, catch basins, and other above-ground components of the drainage system.

What are the Risks of Not Having a Build Over Drainage Survey?

  1. Damage to existing drainage infrastructure: Building over or near existing drains can cause damage to the pipes and other components of the drainage system. This can lead to leaks, blockages, and other issues that can be costly to repair.

  2. Increased risk of flooding: If a new building disrupts the existing drainage system, it can result in an increased risk of flooding for both the new structure and neighbouring properties.

  3. Delays and additional costs: If problems with existing drainage systems are discovered during construction, it can cause delays and additional costs to the project as the necessary drain repairs or adjustments are made.


What are the Benefits of Having a Build Over Drainage Survey?

Protect your investment
A build over drainage survey can help ensure that your building project does not inadvertently damage existing drainage systems, reducing the risk of costly drain repairs further down the line.

Minimize the risk of flooding
By identifying the impact of your construction on existing drainage systems, a build over drainage survey can help minimize the risk of flooding for both your new building and neighbouring properties.

Streamline the construction process
By undertaking a build over drainage survey before construction begins, you can identify any potential issues and incorporate the necessary adjustments into your plans.

This can help to streamline the construction process and minimize the risk of delays and additional costs.


How to Ensure the Survey is Adequately Carried Out

To ensure that a build over drainage survey is carried out correctly, it’s essential to hire experienced professionals who have the necessary expertise and equipment.

When selecting a company to carry out the survey, consider their track record and ask for references from previous clients.

It’s also important to ensure that the company is licensed and insured, as this will provide you with additional peace of mind.

When discussing the survey with the company, make sure that they fully understand the scope of the project and the specific concerns you have about the existing drainage systems.
This will help ensure that the survey is tailored to your needs and provides the information you require to make informed decisions about your project.
Finally, it’s essential to ensure that the survey is carried out in a timely manner, as delays can impact your project timeline and potentially increase costs.
Make sure to agree on a schedule for the survey with the company and monitor their progress to ensure that they are meeting their deadlines.

When Should a Build Over Drainage Survey be Carried Out?

  1. Before purchasing a property: If you are considering buying a piece of land or an existing building for redevelopment, a build over drainage survey can provide valuable information about the state of the existing drainage systems and any potential risks.

  2. Before submitting planning applications: When applying for planning permission or building permits, it can be beneficial to include a build over drainage survey as part of your application. This can help demonstrate to the relevant authorities that you have taken steps to understand and mitigate any risks associated with your project.

  3. During the design phase: As you develop your plans for your building project, it’s essential to consider the impact on existing drainage systems. A build over drainage survey can help inform your design decisions and ensure that you do not inadvertently create problems for the drainage infrastructure.


How Can Build Over Drainage Surveys be Performed?

There are several methods that can be employed to carry out a build over drainage survey, depending on the specific needs of the project and the existing drainage infrastructure.
These methods can include, but are not limited to:

  1. CCTV surveys: Using specialized cameras, professionals can inspect the interior of pipes and other underground structures to assess their condition and identify any potential issues.

  2. Manhole inspections: Manholes and other access points provide an opportunity to physically inspect the condition of drains and sewers, as well as assessing the quality of any above-ground structures such as catch basins or stormwater channels.

  3. Sonde surveys: Using sonde equipment, professionals can create detailed maps of the underground drainage infrastructure, helping to identify any areas of concern or potential risks.


Are Build Over Drainage Surveys Affordable?

The cost of a build over drainage survey can depend on several factors, including the size of the project, the complexity of the existing drainage infrastructure, and the methods used to carry out the survey.
However, it’s important to remember that the cost of a survey is often relatively small when compared to the potential financial risks of not having one carried out.
By identifying potential issues with the drainage infrastructure before construction begins, a build over drainage survey can help to avoid costly delays, repairs, and potential damage to adjacent properties.
As a result, it’s a wise investment that can ultimately save you money in the long run.

What Happens if a Build Over Drainage Survey is Not Carried Out?

If a build over drainage survey is not carried out before construction begins, there is an increased risk of damage to existing drainage infrastructure, resulting in leaks, blockages, and other issues.
This can lead to costly repairs, delays to the construction project, and potential legal issues if nearby properties are affected by flooding.
Additionally, the absence of a build over drainage survey can make it more challenging to obtain planning permission or building permits.
Local authorities may require evidence that the project has considered the impact on existing drainage systems and taken appropriate steps to mitigate any risks.

Should I Get A Build Over Drain Survey?

Carrying out a build over drainage survey is a crucial step in the planning and execution of any building project. It can help protect your investment, minimize the risk of flooding, and streamline the construction process.
By choosing an experienced and professional company to undertake the survey, you can ensure that it is carried out to a high standard and provides the information you need to make informed decisions about your project.
Ultimately, investing in a build over drainage survey can save you time, money, and stress in the long run, making it an essential consideration for any construction project.


Be Sure To Get A Build-Over Survey To Avoid Delays & Costs

If you’re planning an extension or a building project, a build-over survey can help avoid disruption, expenses, and legal matters.

Frequently Asked Questions About Build Over A Drain

It depends on the local building codes and regulations in your area. Before starting any construction project, it’s best to check with your local government or building authority to ensure that you comply with the regulations.
No, building over a drain directly can result in blockages, flooding, and other issues. However, it’s possible to build a structure over a drain using specialized techniques like bridging, cantilevering, or creating a suspended floor.
Building over a drain can result in blockages, flooding, structural damage, and health hazards. It’s essential to consult a professional engineer or contractor to assess the risks and propose appropriate solutions.
You can check your property’s drainage plans or conduct a CCTV survey to locate the drains. It’s also important to consider the drainage patterns and history of the area before proceeding with any construction work.
The materials used for building over drains should be lightweight, durable, and resistant to water and corrosion. Examples include steel, aluminium, composite materials, or light-gauge framing.
In most cases, building over a drain requires planning permission from the local council or authority. The application process may vary depending on the type and size of the structure, the location, and other factors.
Regular maintenance of the drainage system is crucial to ensure its proper function and prevent blockages or damage. This may involve periodic cleaning, inspections, repairs, or upgrades by a qualified professional.
Yes, you can sell a property that has a structure built over a drain, but you need to disclose this information to potential buyers. It’s also important to obtain the necessary permits and ensure the structure complies with the building codes and regulations.
The cost of building over a drain can vary widely depending on the size, complexity, materials, location, and other factors. It’s best to get quotes from several contractors or engineers and compare their proposals.
Some best practices for building over drains include consulting a professional engineer or contractor, obtaining necessary permits and approvals, using suitable materials and techniques, designing for proper drainage and ventilation, and ensuring regular maintenance and inspections.
It’s also crucial to consider the potential risks and impacts of the structure on the drainage system and the surrounding environment.