Build Over Agreements in London
Drainage plans and sectional drawings for Thames Water build over agreements – prepared and submitted in 3–5 days, from £249.
- 24-48 Hour Turnaround
- 100% Compliant
What Is a Build Over Agreement?
If your extension or new build sits over — or within 3 metres of — a public sewer, your water company must give permission before work starts. In London that’s usually Thames Water. A build over agreement is that formal permission, and it needs the right drawings: a site plan showing the sewer route, drainage layouts, and sectional drawings showing your foundations in relation to the pipework.
Get it wrong and work can be stopped — or you may have to expose the sewer afterwards at your own cost. We prepare the full drawing package and handle the application for you, as your agent. Where foundation design is involved, we can also provide the structural calculations your project needs — and if you need building regulation drawings for the wider project, we do those too.
Why Choose A2Z for Your Build Over Agreement?
Everything you need for a smooth build over agreement — drawings, application handling and technical support in one place.
Application Handled for You
We prepare the drawings and submit the application to your water company as your agent.
Fixed Fees from £249
Written quotation before we start. The water company's application fees are billed separately.
3–5 Day Turnaround
Drawing packages issued in 3–5 days as standard, so your project keeps moving.
Drainage Plans Included
Site plans and drainage layouts showing the sewer route, manholes and connections.
Sectional Drawings
Foundation design shown in relation to the pipework, as the water company requires.
Thames Water Experience
Drawings prepared to Thames Water requirements, across London, Essex and Kent.
Our 4-Step Process
From initial consultation to final delivery, we ensure every step meets the highest professional standards
Send Your Plans
Existing and proposed drawings, plus any drainage information you have.
We Prepare the Package
Drainage plans and sectional drawings drawn up for the application.
Application Submitted
We submit everything to the water company as your agent.
Queries Handled
We respond to any technical questions until your agreement is in place.
Frequently Asked Questions
What is a build over agreement?
Formal permission from your water company to build over — or within 3 metres of — a public sewer. In London, that is usually Thames Water.
How much does a build over agreement cost?
Our fixed fees start from £249, confirmed in a written quotation before we start. The water company's own application fees are billed separately.
How long does a build over agreement take?
We issue your drawing package in 3–5 days as standard, then submit the application to the water company as your agent.
What drawings are needed for a build over agreement?
A site plan showing the sewer route, drainage layouts showing manholes and connections, and sectional drawings showing your foundations in relation to the pipework.
Do you submit the application for me?
Yes. We act as your agent — preparing the drawings and submitting the full application to Thames Water or your local water company, and handling any technical queries.
Which areas do you cover?
We handle build over agreements across London, Essex and Kent.
Ready to Start Your Structural Engineering Project?
Join hundreds of satisfied clients who trust A2Z Structural Engineering for their property projects. Get your free consultation today and discover how we can help bring your vision to life.
Fast Turnaround
Most projects completed within 5-7 days
UK Compliant
All work meets current regulations
Satisfaction Guaranteed
98% client satisfaction rate
