Handover & Completion · Mandatory · Completion

As-Built Drawings Package

The complete package of as-built drawings showing the final installed condition of all works.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. CDM 2015 / Contract remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	CDM 2015 / Contract
Status	Mandatory
Prepared by	Principal Contractor
CDM requirement	The CDM health and safety file requires as-built drawings to be included as part of the permanent project record
Critical content	Buried services, MEP as installed, structural layout, fire compartmentation

1. As-Built Drawings — The Permanent Record of the Building

As-built drawings are the authoritative record of the building as actually constructed. They show the final, installed condition of all elements of the building, incorporating every change, variation, and site adjustment that occurred during construction. The as-built drawing set is the definitive reference that the building owner, facilities manager, and future designers will rely upon for the entire operational life of the building.

As-built drawings are critically important for hidden elements — those parts of the building that are concealed within the structure and cannot be visually inspected once construction is complete. Buried services (drainage, water mains, gas mains, electrical cables, and data ducts below ground), MEP installations within walls, floors, and ceilings, structural steelwork encased in fire protection or concrete, and fire compartmentation lines are all elements whose location and configuration can only be determined from accurate as-built records. Without these records, future maintenance, alteration, and refurbishment works carry significant risk of damage to hidden services and structural elements.

Under CDM 2015, the principal designer is required to prepare a health and safety file containing information likely to be needed to ensure health and safety during any subsequent work on the building. As-built drawings are a core component of the health and safety file. The contract will also typically require the contractor to provide a complete set of as-built drawings as a condition of practical completion or as a pre-condition of the release of retention.

Mark up drawings throughout the project

Red-line as-built markups on construction drawings throughout the project — not retrospectively at handover. Site teams should mark up changes on drawings as the work is carried out, while the information is fresh and accurate. Retrospective as-built markups produced from memory weeks or months after the work was completed are unreliable and often inaccurate, particularly for buried services and concealed elements.

2. As-Built Drawings Package Contents

The following table sets out the key components of a comprehensive as-built drawings package. Each element must show the building as actually constructed, not as originally designed.

Component	Description
Drawing register	A comprehensive register listing every as-built drawing by number, revision, title, discipline, and date. The register must confirm the final revision status of each drawing and provide a clear index for locating specific information.
Structural drawings	As-built structural drawings showing foundations, substructure, superstructure, steelwork, reinforced concrete, and all structural connections as actually constructed. Includes any changes to structural member sizes, positions, or details that differ from the original design.
Architectural drawings	As-built architectural drawings showing floor plans, elevations, sections, roof plans, and details as actually constructed. Includes all changes to room layouts, door and window positions, partition locations, floor finishes, and ceiling layouts.
MEP as-built drawings	As-built mechanical, electrical, and plumbing drawings showing all services as actually installed. Includes ductwork routes, pipework routes, cable routes, distribution board locations, plant positions, and all changes from the original design drawings.
Buried services drawings	As-built drawings of all below-ground services including drainage (foul and surface water), water mains, gas mains, electrical cables, telecommunications ducts, and any other buried infrastructure. These must include accurate depths, offsets from buildings and boundaries, and GPS coordinates where available. Buried services drawings are among the most critical as-built records because they cannot be verified by visual inspection once backfilled.
External wall details (higher-risk buildings)	For higher-risk buildings, detailed as-built drawings of the external wall construction showing the actual materials, cavity barriers, fire stopping, and insulation as installed. This is a requirement under the Building Safety Act 2022 for buildings within scope and is critical for demonstrating compliance with fire safety requirements.
Commissioning drawings	Schematic and layout drawings used during the commissioning process, annotated with final commissioning data, set points, flow rates, and system performance figures. These form part of the operational record and are cross-referenced to the O&M manual.
Format and delivery	As-built drawings should be delivered in both native CAD format (DWG) and PDF. On BIM-enabled projects, the as-built model (typically IFC or native Revit) should be updated to reflect as-built conditions and delivered as a federated model. Paper copies may be provided as a supplement but are not an acceptable primary deliverable.

3. Common Mistakes

Providing original design drawings as as-built

One of the most common and most serious failures is providing the original design drawings, unmarked and unrevised, as the as-built record. Design drawings show the building as intended, not as constructed. Every construction project involves changes — site variations, RFIs, coordination adjustments, and unforeseen conditions all result in the constructed building differing from the original design. Providing design drawings as as-builts gives the building owner a false record that cannot be relied upon for future maintenance, alterations, or emergency response.

Missing buried services records

Buried services are the single most critical element of the as-built record because their location cannot be determined by visual inspection once backfilled. Failure to provide accurate as-built records of buried drainage, water mains, gas mains, electrical cables, and telecommunications ducts creates a permanent risk for anyone who needs to carry out future excavation works. Strikes on buried services cause injuries, fatalities, service disruptions, and environmental contamination. Buried services should be surveyed and recorded before backfilling, with accurate depths and offsets.

Not indexing the drawing package

Delivering a collection of drawings without a comprehensive drawing register and index makes the package difficult to use and undermines its value as a reference document. The drawing register should list every drawing by number, revision, title, discipline, and date, and should be structured to allow the user to locate any specific drawing quickly. Without a clear index, drawings are effectively lost within the package and may never be found when they are needed.

Paper format only

Delivering as-built drawings only in paper format is inadequate for modern facilities management. Paper drawings cannot be searched, cannot be easily reproduced, deteriorate over time, and cannot be integrated with digital facilities management systems. As-built drawings should be delivered in electronic format (PDF as a minimum, native CAD and BIM models where available) as the primary deliverable. Paper copies may be provided as a supplement but should not be the sole format.

Not linking to O&M and health and safety file

As-built drawings should be cross-referenced to the O&M manual and the CDM health and safety file. The three documents together form the complete handover record for the building. Delivering them as disconnected, standalone documents reduces their usefulness and increases the risk that critical information is overlooked. The O&M manual should reference specific as-built drawings for each system, and the health and safety file should include or reference the as-built drawings that are relevant to future maintenance and construction safety.

4. Frequently Asked Questions

Who is responsible for producing as-built drawings?▾

The principal contractor is responsible for producing and delivering the as-built drawing package. In practice, the principal contractor co-ordinates submissions from subcontractors, each of whom is responsible for providing as-built drawings for their own scope of work. The design team (architect, structural engineer, MEP consultant) may also be required to update their design drawings to as-built status based on information provided by the contractor. The contract should clearly define responsibilities for as-built drawing production, including which parties are responsible for which disciplines, the required format, and the submission deadline.

How long should as-built drawings be retained?▾

As-built drawings should be retained for the entire life of the building. They are a permanent record and remain relevant for as long as the building exists. The CDM health and safety file, which includes as-built drawings, must be kept available for inspection for the life of the structure under CDM 2015. Even when refurbishment or alteration works are carried out and new as-built drawings are produced, the original as-built records should be retained because they contain information about the original construction that may be relevant to future works, structural assessments, or dispute resolution.

What is the relationship between as-built drawings and BIM?▾

On BIM-enabled projects, the as-built record may be delivered as an updated BIM model (the asset information model) rather than, or in addition to, traditional 2D drawings. The BIM model is updated to reflect as-built conditions based on site surveys, red-line markups, and commissioning data. The as-built BIM model provides a three-dimensional, data-rich record of the building that can be used for facilities management, space planning, maintenance scheduling, and future design work. However, 2D drawings (extracted from the model or produced separately) are typically still required as a human-readable reference, and the contract should specify both deliverables.

What is the difference between as-installed and as-built drawings?▾

The terms are often used interchangeably, but there is a distinction. As-installed drawings typically refer to drawings produced by a subcontractor showing their specific installation as completed (for example, as-installed ductwork drawings from the mechanical subcontractor). As-built drawings refer to the final, co-ordinated drawing set that shows the entire building as constructed, incorporating all as-installed information from all trades into a single, consistent record. The as-built drawing package is the consolidated, project-wide record, while as-installed drawings are the trade-specific inputs that feed into it.

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