TL;DR: An as-built survey is the process of measuring and documenting the actual position and dimensions of constructed works after completion, comparing them against design to produce a permanent record of what was built. Australian Standard AS 5488 and project contracts typically require as-built documentation for handover. The cost of not having accurate as-built records—rework, disputes, delayed maintenance, and failed audits—far exceeds the cost of commissioning the survey. This guide explains what as-built surveying involves, how it is conducted, what standards apply, and how to ensure your project gets the documentation it needs.
Key Takeaways
- As-built surveys document the actual constructed position of all project elements—structures, services, earthworks, and infrastructure—creating a permanent record that is essential for maintenance, operation, and future modification (Australian Standard AS 5488, 2019)
- The gap between design and constructed position typically ranges from 10 mm to over 500 mm depending on project type, with earthworks showing the largest deviations and precision structures the smallest
- Australian Standards, state building regulations, and most construction contracts mandate as-built documentation; failure to provide it can block practical completion, delay handover, and create liability exposure
- Modern as-built survey combines total station measurement, 3D laser scanning, and UAV photogrammetry to capture comprehensive data efficiently; the choice of method depends on project type, accuracy requirement, and budget
- Digital as-built delivery in formats compatible with asset management systems (AutoCAD, Revit, 12d Model, GIS) is now standard expectation, replacing paper-based handover documentation
Table of Contents
- What is an as-built survey?
- Why as-built surveys matter: the cost of not knowing
- When as-built surveys are required
- The as-built survey process: a 6-step framework
- As-built survey methods and technology
- Deliverables and standards
- Accuracy requirements by project type
- Cost guide: what to budget for as-built surveying
- Common problems and how to avoid them
- Frequently asked questions
- What to do next
What is an as-built survey?
An as-built survey—also called an as-constructed survey, final survey, or works-as-executed survey—is the measurement and documentation of a constructed project's actual position, dimensions, and levels after construction is complete. It produces a record of what was actually built, as opposed to what was designed.
This distinction matters because construction is not a perfect replication of design. Earthworks settle. Concrete formwork moves during pour. Steel members are adjusted in the field. Underground services are routed around unexpected obstructions. Tolerances are specified for a reason: perfect construction is impossible and unnecessary. But the deviations matter—they must be known, measured, and recorded.
Definition: As-built survey An as-built survey is a post-construction survey that documents the actual three-dimensional position, dimensions, and configuration of constructed works. The survey compares as-built conditions against design intent, identifies and quantifies deviations, and produces a permanent digital or drawn record suitable for asset management, maintenance planning, and future design work.
The scope of an as-built survey varies with project type:
- Building projects — Footing locations, slab levels, structural steel positions, facade alignment, floor flatness, services locations
- Civil infrastructure — Road alignment and levels, drainage positions, pavement thickness verification, kerb and channel locations, retaining wall positions
- Industrial facilities — Equipment positions, pipework routes, conveyor alignments, tank positions, structural connections
- Underground services — Pipe invert levels, conduit routes, pit locations, cable depths
- Environmental works — Rehabilitation landforms, drainage features, revegetation boundaries
As-built surveys serve multiple stakeholders. The asset owner needs records for maintenance and operation. The facility manager needs to know where services run before digging. Future designers need accurate existing conditions before planning upgrades. Regulators need evidence that works comply with approved plans. Each stakeholder depends on the as-built survey being accurate, comprehensive, and accessible.
Why as-built surveys matter: the cost of not knowing
The value of an as-built survey is most visible when it is absent. Projects without accurate as-built records face predictable and expensive problems:
Rework on upgrades and retrofits. When a design team models an upgrade using original design drawings rather than as-built conditions, clashes and interferences are inevitable. A pipe route that looks clear on the design drawing may pass directly through a structural member that was relocated during construction. Identifying this clash in the field costs 10-20 times more than identifying it in the design office. 3D laser scanning of existing conditions before design work begins is the most reliable way to prevent these problems.
Service strike incidents. Hitting an unrecorded underground service during excavation is dangerous and expensive. Dial Before You Dig plans are based on as-built records—if those records are inaccurate or absent, the plans are wrong. A single service strike can cost hundreds of thousands in repairs, downtime, and liability.
Disputes and claims. Construction disputes frequently hinge on whether works were built to specification. Without an as-built survey, the owner's position is weakened—they cannot prove non-compliance, nor can they defend against claims of defective work. The as-built survey is the factual baseline for dispute resolution.
Failed audits and compliance failures. Regulatory audits of mining, environmental, and building works increasingly require as-built documentation. Failure to produce it can result in stop-work orders, fines, and revocation of approvals.
Delayed practical completion. Most construction contracts require as-built documentation as a condition of practical completion. Delays in producing the as-built survey delay handover, payment, and the commencement of defects liability periods.
| Scenario | Cost without as-built | Cost with as-built |
|---|---|---|
| Clash detected in field during retrofit | $50,000-$500,000 | $2,000-$10,000 (scan before design) |
| Service strike during excavation | $100,000-$2,000,000 | $5,000-$15,000 (accurate records) |
| Construction dispute (no as-built evidence) | $200,000-$5,000,000+ | $10,000-$50,000 (survey as evidence) |
| Delayed practical completion | $10,000-$100,000/day | On-time handover |
| Regulatory non-compliance fine | $50,000-$500,000 | Compliance demonstrated |
Note: Figures are illustrative, based on industry experience. Actual costs vary significantly by project.
When as-built surveys are required
As-built surveys are mandatory under multiple Australian standards and regulatory frameworks:
Australian Standard AS 5488 — Classification of Subsurface Utility Information. This standard specifies requirements for recording the location of underground services, including as-laid positions, depths, and attributes. Compliance is required by most road authorities and utility owners.
State building regulations. Each state and territory requires as-built documentation for building works as a condition of occupation certificate or final inspection. The specific requirements vary but generally include footing locations, slab levels, structural elements, and services positions.
Construction contracts. Standard form contracts (AS 4000, AS 2124, and their derivatives) typically include clauses requiring the contractor to provide as-built drawings and documentation. Failure to comply can result in payment withholding and dispute.
Mining and environmental approvals. Mining leases, environmental licences, and development approvals typically require as-built documentation of works as a condition of compliance. This includes rehabilitation landforms, drainage structures, containment facilities, and infrastructure positions.
Project-specific requirements. Major projects often specify as-built survey requirements in the technical specifications, including accuracy standards, deliverable formats, and submission timeframes.
The as-built survey process: a 6-step framework
Step 1: Scope definition and specification review
The as-built survey process begins before construction finishes. The surveyor reviews the project specifications, design drawings, and contract requirements to define the scope:
- What elements must be surveyed (structures, services, earthworks, all of the above)?
- What accuracy is required?
- What coordinate system and datum must be used?
- What deliverable formats are specified?
- What is the submission deadline relative to practical completion?
Step 2: Control establishment
The as-built survey must be tied to the project's survey control network. If the original control points still exist, they are verified and used. If they have been destroyed or are inadequate, new control is established. The control network is the spatial backbone of the as-built survey—everything measured must connect back to it.
Step 3: Field measurement
The surveyor measures the constructed elements using appropriate technology (see methods section below). Key principles:
- Measure critical points: corners, centres, inverts, invert levels, surface levels, connection points
- Photograph everything: photographs provide context and supporting evidence for measurements
- Record deviations: where constructed position differs from design, measure and record the deviation
- Check completeness: ensure nothing specified in the scope has been missed
Step 4: Data processing and comparison
Field measurements are processed, adjusted, and compared against design:
- Coordinates and levels are calculated and checked
- As-built positions are plotted against design positions
- Deviations are calculated and tabulated
- Deviations outside specified tolerances are flagged for review
Step 5: Drafting and documentation
The as-built survey is drafted into specified deliverable formats:
- Plans showing as-built positions with design positions for comparison
- Long sections and cross-sections where required
- Tables of coordinates, levels, and deviations
- Photographic records
- Metadata: survey date, surveyor, equipment, accuracy, coordinate system
Step 6: Review and submission
The deliverables are reviewed for completeness and accuracy, then submitted to the project team for approval and inclusion in the handover package.
As-built survey methods and technology
The choice of survey method depends on project type, accuracy requirement, access constraints, and budget.
Total station survey
The traditional and still widely used method. A total station measures angles and distances to targeted points, producing coordinates and levels. Best for discrete point measurement where high accuracy is required and the number of points is manageable.
| Attribute | Specification |
|---|---|
| Accuracy | 2-5 mm typical |
| Point rate | 1-3 points per minute |
| Best for | Building set-out verification, services pits, structural points |
| Limitations | Requires line of sight; point-by-point measurement is slow for large areas |
3D laser scanning
Laser scanning captures millions of points per second, producing dense point clouds that represent the entire visible environment. Best for complex structures, facilities with dense services, and projects where comprehensive documentation is required.
| Attribute | Specification |
|---|---|
| Accuracy | 2-6 mm typical |
| Point rate | 1-2 million points per second |
| Best for | Plant and facility documentation, complex structures, heritage recording |
| Limitations | Large data volumes; requires specialist software and processing time |
See our article on what is 3D laser scanning for a comprehensive explanation of the technology.
UAV/drone photogrammetry
Drone photogrammetry captures aerial imagery that is processed into 3D models, orthophotos, and digital surface models. Best for earthworks, open areas, stockpiles, and large sites where ground access is difficult.
| Attribute | Specification |
|---|---|
| Accuracy | 10-50 mm horizontal, 20-100 mm vertical (with GCPs) |
| Coverage rate | 10-100 hectares per flight |
| Best for | Earthworks, open-cut mines, large sites, progress monitoring |
| Limitations | Less accurate than total station or scanning; requires ground control |
GPS/GNSS survey
GPS and GNSS receivers determine position using satellite signals. Best for large-scale projects where high absolute accuracy across wide areas is required.
| Attribute | Specification |
|---|---|
| Accuracy | 10-20 mm horizontal, 20-40 mm vertical (RTK) |
| Coverage rate | Unlimited (satellite dependent) |
| Best for | Large sites, road corridors, boundary verification |
| Limitations | Requires sky view; less accurate in vertical than horizontal |
Most as-built surveys use a combination of these methods. A building project might use total station for structural points and services, laser scanning for complex MEP areas, and GPS for site-wide control. The key is selecting the right tool for each element of the project.
Deliverables and standards
As-built survey deliverables vary by project and client requirements. Common deliverables include:
| Deliverable | Format | Description |
|---|---|---|
| As-built plan | DWG, PDF | Plan showing as-built positions with design comparison |
| As-built long section | DWG, PDF | Longitudinal section showing design vs as-built levels |
| As-built cross-sections | DWG, PDF | Cross-sections at specified intervals |
| Coordinate and level table | CSV, XLSX | Tabulated as-built coordinates and levels with deviations |
| Point cloud | E57, LAS, RCP | 3D point cloud from laser scanning |
| 3D model | DWG, RVT, IFC | Modelled as-built geometry |
| Photographic record | JPG, PDF | Georeferenced photographs of key features |
| Survey report | Methodology, accuracy, coordinate system, metadata |
Australian Standards relevant to as-built survey include:
- AS 5488 — Classification of Subsurface Utility Information (for underground services)
- AS 1418 — Cranes (including requirements for crane rail survey and certification)
- AS 3600 — Concrete structures (including tolerances for concrete construction)
- AS 4100 — Steel structures (including tolerances for steel construction)
- State-specific requirements — Each state road authority, building regulator, and mining department has specific as-built documentation requirements
Accuracy requirements by project type
Accuracy requirements for as-built surveys vary significantly by project type and element:
| Project Element | Typical Tolerance | Survey Method |
|---|---|---|
| Building footing position | ±10-25 mm | Total station, GPS |
| Structural steel position | ±5-15 mm | Total station, laser scanning |
| Slab level (FF/FL) | ±3-10 mm | Total station, laser scanning |
| Underground pipe invert | ±10-25 mm | Total station |
| Road centreline | ±25-50 mm | Total station, GPS |
| Drainage pit position | ±25-50 mm | Total station, GPS |
| Earthworks surface | ±50-100 mm | GPS, drone photogrammetry |
| Conveyor alignment | ±2-5 mm | Total station, laser scanning |
| Crane rail alignment | ±1-3 mm | Total station, laser scanning |
The project specifications override these typical values. Always verify the specified tolerances before commencing as-built survey work.
Cost guide: what to budget for as-built surveying
As-built survey costs vary with project size, complexity, accuracy requirements, and deliverable specifications. The following ranges provide indicative guidance:
| Project Type | Size | Typical As-Built Cost Range |
|---|---|---|
| Small building | < 500 m² | $3,000-$8,000 |
| Medium building | 500-2,000 m² | $6,000-$15,000 |
| Large building | 2,000-10,000 m² | $12,000-$40,000 |
| Major building/facility | > 10,000 m² | $30,000-$100,000+ |
| Small civil project | < 1 km | $5,000-$12,000 |
| Road project | 1-10 km | $10,000-$50,000 |
| Major road project | > 10 km | $40,000-$150,000+ |
| Industrial plant | Variable | $15,000-$100,000+ |
Factors that increase cost:
- High accuracy requirements (sub-5 mm)
- Complex geometry requiring laser scanning
- Restricted access requiring specialised equipment or working at heights
- Tight timeframes requiring overtime or additional crew
- Extensive underground services requiring potholing or utility location
- Intelligent modelling requirements (BIM/Revit deliverables)
Factors that reduce cost:
- Good existing survey control
- Clear scope and specifications
- Unrestricted access during business hours
- Simple geometry measurable by total station
- Standard CAD deliverables only
Common problems and how to avoid them
Problem: Survey scope not defined until after construction
Solution: Define as-built survey requirements in the project specifications before construction begins. Specify what will be surveyed, to what accuracy, in what format, and by when.
Problem: Original survey control destroyed
Solution: Require the construction surveyor to establish permanent control points and provide their coordinates to the as-built surveyor. Include control point protection in site management plans.
Problem: Underground services not accessible for measurement
Solution: Require services to be surveyed during installation when they are exposed, not after backfilling. Use GPR (ground-penetrating radar) to locate services where as-laid records are poor.
Problem: Incomplete deliverables
Solution: Use a deliverable checklist tied to the project specifications. Require the surveyor to confirm each element has been captured before submission.
Problem: Wrong coordinate system or datum
Solution: Explicitly specify the required coordinate system and datum in the survey brief. Verify that the surveyor has worked in the correct system before accepting deliverables.
Frequently asked questions
What is the difference between an as-built survey and a set-out survey?
A set-out survey establishes the design position on the ground before construction, guiding the builder where to build. An as-built survey measures what was actually built after construction is complete. They are opposite ends of the construction process: set-out tells the builder where to put things; as-built records where they actually ended up.
How soon after construction should the as-built survey be done?
Ideally, as-built survey is conducted progressively during construction—services as they are laid, structures as they are completed—rather than in a single pass at the end. Progressive surveying captures elements while they are still accessible and fresh in the minds of those who installed them. For elements that can only be surveyed after completion (slab levels, finished surfaces), the survey should be conducted as soon as practical after construction finishes and before temporary works are removed.
Can as-built surveys be done while the plant is operating?
Yes, with appropriate safety measures. As-built survey of operating facilities requires coordination with operations personnel, adherence to isolation and permit-to-work systems, and awareness of hazards. 3D laser scanning is particularly valuable for operating facilities because it captures comprehensive data quickly, minimising the time surveyors spend in hazardous areas.
What software is used for as-built survey processing?
Common software includes: Leica Infinity, Trimble Business Center, 12d Model, AutoCAD Civil 3D, Bentley MicroStation, Autodesk Revit (for BIM deliverables), and CloudCompare (for point cloud processing). The choice depends on project requirements and client preferences.
Who pays for the as-built survey?
In most construction contracts, the contractor is responsible for providing as-built documentation as a condition of practical completion. The contractor may perform the work with their own surveyors or engage a specialist survey firm. In some arrangements, the owner commissions the as-built survey independently to ensure objectivity.
What to do next
If you are managing a project that requires as-built survey documentation:
- Review your contract and specifications — Identify the specific as-built survey requirements, accuracy standards, and deliverable formats specified for your project.
- Engage a surveyor early — The best as-built surveys are planned before construction begins. Engage your surveyor during the pre-construction phase to review scope and methodology.
- Call us on 0407 057 015 — Discuss your project with a surveyor who can scope the as-built survey requirements, provide a fixed-price quotation, and ensure your handover documentation meets all contractual and regulatory requirements.
Industrial Spatial Solutions provides as-built surveying services across Australia for construction, industrial, mining, and infrastructure projects. We deliver in your required formats, to your specified accuracy, on your timeline.
Industrial Spatial Solutions — As-built accuracy, handover ready, compliance assured.
Related reading: What is 3D laser scanning, How to prepare for a shutdown survey, Topographical surveying guide