What are As-Built Drawings?

Construction projects rarely finish exactly as they were originally designed. Changes made on site, whether due to ground conditions, design revisions or unforeseen challenges, mean the completed works can differ from the approved drawings.

As-built drawings provide an accurate record of what was actually constructed, giving contractors, developers and asset owners confidence that completed works have been delivered as intended.

Whether they’re required for statutory adoption, BIM handover or future maintenance, accurate as-built drawings play an essential role in achieving a smooth project handover and ensuring reliable records for years to come.

So, What is an As-Built Drawing?

An as-built drawing is an accurate, measured record of a completed structure, road, drainage network, utility or other constructed asset. Produced once construction works have been completed, it records what has actually been built rather than what was originally proposed, providing an essential reference for project handover, future maintenance and statutory adoption.

Unlike design or construction drawings, which show how a project is intended to be built, as-built drawings reflect the final completed works. They record any changes made during construction, whether due to site conditions, engineering decisions or design amendments, ensuring the finished asset is accurately documented.

Depending on the project, as-built deliverables may include topographical surveys, drainage records supported by CCTV survey data, utility surveys and structural records. The specific requirements will vary depending on the project and the adopting authority, so it’s important to establish the required outputs before survey work begins.

Across the UK, accurate as-built data supports statutory adoption processes including S104 sewer adoption, S38 and S278 highway adoption, and S185 sewer diversions. It also forms an important part of BIM handover, facilities management and long-term asset management.

To ensure the required level of accuracy, as-built surveys should always be undertaken by experienced surveyors using calibrated equipment and verified survey control, with the survey specification agreed in advance with both the client and, where applicable, the adopting authority.

How As-Built Drawings are Produced

Producing an accurate as-built drawing involves far more than updating the original design. It requires precise measurement, careful verification and thorough quality assurance to ensure the completed works are accurately recorded and meet the requirements of the relevant authority or client.

1. Confirm the project requirements

Before any survey work begins, it’s important to understand how the as-built drawings will be used. Whether they’re required for HADDMS, S104 sewer adoption, S38 or S278 highway adoption, S185 sewer diversions, private development handover or BIM and facilities management, the intended use will determine the level of detail, required standards and file formats needed.

2. Review the approved design information

The surveying team reviews the approved design drawings, specifications and any relevant technical information before attending site. This provides a clear understanding of what was originally intended and establishes the benchmark against which the completed works will be measured.

3. Establish or verify survey control

Reliable survey control forms the foundation of any accurate as-built survey. Existing control points are checked, or new control is established to ensure all measurements are tied into a consistent coordinate system, producing repeatable and defensible results.

5. Integrate additional survey information

Where required, specialist survey information is combined with the topographical survey. For drainage adoption, for example, CCTV survey data may be integrated to demonstrate pipe locations, gradients, connectivity and compliance with S104 sewer adoption requirements or Highways England HADDMS specification.

6. Process and compare the data

Once the site survey is complete, the collected information is processed and compared against the approved design if necessary. Any differences between the approved drawings and the completed construction can be identified, allowing project teams to resolve any issues before submission or handover where necessary.

7. Produce the as-built drawings

The processed survey data is used to produce accurate CAD drawings, GIS information or BIM deliverables, depending on the project requirements. Drawings are prepared to the specification required by the client, consulting engineer or adopting authority, ensuring they are ready for submission and review.

8. Quality assurance and delivery

Before the drawings are issued, they undergo thorough internal quality checks to ensure accuracy, consistency and compliance with the relevant standards. Once complete, the final as-built information is delivered in the agreed formats, providing a reliable record of the completed works for handover, adoption or future asset management.

As-Built Drawings and Adoption Surveys at Kemp Engineering Surveys

At Kemp Engineering Surveys, we provide accurate as-built and adoption surveys that help clients achieve smooth project handover and successful adoption. From drainage and highways to utilities, structures and public realm works, our experienced surveyors produce dependable verification data that demonstrates completed works have been constructed in accordance with the approved design.

Using industry-leading total stations, GPS/GNSS technology and terrestrial laser scanning, our RICS-regulated surveyors deliver accurate survey information trusted by contractors, developers, consulting engineers, local authorities and water companies alike. We also combine topographical survey data with CCTV inspection information, where required, to support S104 sewer adoption.

Since 1988, we’ve delivered as-built and adoption surveys for projects ranging from small residential developments to large civil engineering and infrastructure schemes. Working with organisations including Cornwall Council, Devon County Council and leading Tier 1 contractors, we understand the standards expected by adopting authorities and provide survey outputs that help keep projects moving towards successful approval and sign-off.

An accurate as-built drawing is what stands between your project and a smooth handover. Whether you need as-built data for S104 sewer adoption, S38 highway adoption or BIM and facilities management records, the Kemp team can advise on the right approach for your project.

Get in touch to discuss your requirements.