This as built surveys FAQ answers the questions Australian project engineers, asset owners, contractors and facility managers ask most often before commissioning a record of what was actually built. We cover what an as-built captures, how accurate it is, which standards apply, what it costs and how it is delivered — answered from ISS field experience across mine sites, processing plants, ports and civil infrastructure. Where it matters we name the standards, datums, tolerances and equipment rather than speaking in generalities.
Key takeaways
- An as-built survey (also called as-constructed or works-as-executed) measures the actual three-dimensional position of finished works and compares it against design intent, producing the permanent record relied on for maintenance, retrofits, disputes and compliance.
- Method governs accuracy: a Leica total station gives 2-5 mm on discrete structural and services points, a Leica RTC360 or FARO Focus scanner gives 2-6 mm across complex plant, and DJI drone photogrammetry resolves 10-50 mm horizontal on earthworks and open sites with ground control.
- Standards and contracts drive the requirement — AS 5488 for subsurface utilities, AS 4000 and AS 2124 contract clauses, plus AS 1418 (cranes), AS 3600 (concrete) and AS 4100 (steel) tolerances — and missing as-builts can block practical completion.
- Indicative pricing runs from roughly AUD 3,000 for a small building to AUD 15,000-100,000+ for an industrial plant, with high accuracy, restricted access and BIM modelling the main cost drivers.
- ISS delivers to GDA2020 / MGA2020 and AHD or your local mine grid, in the formats your asset systems use — DWG, E57/LAS point cloud, RVT/IFC model and a signed report with metadata.
What does an as-built survey actually capture?
An as-built survey records the actual position, dimensions and levels of constructed works once construction is finished, as opposed to what the design drawings specified. Construction is never a perfect replica of design — earthworks settle, formwork moves during the pour, steel members are adjusted in the field, and underground services are routed around obstructions found in the trench. The as-built survey measures those real positions, quantifies the deviation from design, and turns it into a permanent record.
Scope follows the project. On a building it is footing positions, slab levels, structural steel, facade alignment and services locations. On civil works it is road alignment and levels, drainage inverts, kerb and pavement. On an industrial facility it is equipment positions, pipe routes, conveyor alignments, tank positions and structural connections. On underground services it is pipe invert levels, conduit routes, pit locations and cable depths. The deliverable speaks to several audiences at once — the asset owner maintaining the plant, the facility manager who needs to know where a service runs before excavating, the design team planning the next upgrade, and the regulator confirming the works match the approval.
How accurate is an as-built survey?
Accuracy is task-dependent, and we match the instrument to the tolerance the deliverable has to support. For discrete points where precision matters — structural steel, machined surfaces, services pits, slab finished levels — a Leica total station delivers 2-5 mm positional accuracy, and precise levelling resolves height to better than a millimetre. For capturing complete geometry across congested plant or complex structures, a terrestrial scanner such as the Leica RTC360 or FARO Focus gives 2-6 mm point accuracy in real conditions of dust, mixed reflectance and vibration — well short of the headline 1 mm laboratory figure but more than adequate for clash detection, dimensional control and modelling.
For earthworks, open-cut areas, stockpiles and large sites, DJI drone photogrammetry flown under CASA Part 101 captures 10-50 mm horizontal and 20-100 mm vertical accuracy with surveyed ground control. Most real projects blend these: a plant as-built might use total station for crane-rail and conveyor datums, laser scanning for the surrounding steel and pipe racks, and a drone for the external yard. The project specification always overrides the typical figures — a crane rail held to ±1-3 mm under AS 1418 demands a different approach to a road centreline at ±25-50 mm.
What standards and contracts require an as-built?
As-built documentation is rarely optional. AS 5488 (Classification of Subsurface Utility Information) sets the requirements for recording underground services — as-laid positions, depths and attributes — and is required by most road authorities and utility owners. Standard-form construction contracts such as AS 4000 and AS 2124 carry clauses obliging the contractor to hand over as-built drawings, and withholding payment for non-compliance is common. Construction tolerances themselves are governed by AS 3600 for concrete and AS 4100 for steel, which the as-built measures against.
Beyond those, each state building regulator requires as-built records as a condition of an occupation certificate, and mining leases, environmental licences and development approvals typically require as-built documentation of rehabilitation landforms, drainage structures, containment facilities and infrastructure as a compliance condition. The practical consequence is simple: define the as-built requirement — what, to what accuracy, in what format, by when — in the specification before construction begins, not as an afterthought at handover.
When should the survey be done?
Progressively, wherever possible. The best as-builts are captured as construction proceeds — services surveyed while the trench is open, structures recorded as they top out — rather than in one pass at the end. Progressive capture catches elements while they are still accessible and before backfill, cladding or temporary works hide them. The most expensive as-built mistake is surveying an underground pipe after the trench is closed: the alternative is exposing it again or relying on ground-penetrating radar, both of which cost more than a five-minute pick-up at the right moment.
For elements that can only be measured once finished — slab finished levels, final surfaces, completed equipment positions — schedule the survey as soon as practical after construction and before the area is demobilised. On operating plant the same logic applies inside a shutdown window: the time to capture a complete as-built of a SAG mill, kiln or congested pipe rack is while it is stopped, isolated and open, which is why as-built scanning is a core part of turnaround scope.
How much does an as-built survey cost in Australia?
Cost is driven by size, complexity, accuracy, access and deliverable format. The ranges below are indicative; a fixed-price quote against a defined scope is always more useful than a rate card.
| Project type | Indicative cost (AUD) |
|---|---|
| Small building (< 500 m²) | 3,000 - 8,000 |
| Medium building (500-2,000 m²) | 6,000 - 15,000 |
| Large building or facility (> 2,000 m²) | 12,000 - 40,000+ |
| Civil / road project (1-10 km) | 10,000 - 50,000 |
| Industrial plant | 15,000 - 100,000+ |
What pushes cost up: sub-5 mm accuracy requirements, complex geometry needing laser scanning, restricted access or working at heights, tight timeframes forcing overtime, extensive underground services requiring potholing or utility location, and intelligent BIM or Revit modelling. What pulls it down: good existing survey control, a clear scope, unrestricted business-hours access, simple geometry measurable by total station, and standard CAD-only deliverables. The real economics, though, sit in what an accurate as-built prevents — a single clash caught in the design office rather than the field, or one avoided service strike, typically covers the survey many times over.
What deliverables do you get?
The deliverable suite is matched to how your team will use the data, and tied to your coordinate framework. For any Australian site we deliver horizontally to GDA2020 with MGA2020 grid coordinates and vertically to AHD, and on mine sites we transform into your local mine grid so the file speaks the language your surveyors and engineers already use.
| Deliverable | Format | Use |
|---|---|---|
| As-built plan with design comparison | DWG, PDF | Records position and quantifies deviation |
| Long sections and cross-sections | DWG, PDF | Level comparison along and across the works |
| Coordinate, level and deviation table | CSV, XLSX | Tabulated evidence for QA and certification |
| Registered point cloud | E57, LAS, RCP | Complete scene for later interrogation |
| As-built 3D model | DWG, RVT, IFC | Modelled geometry for BIM and retrofit design |
| Survey report | Methodology, accuracy, datum and metadata |
A registered point cloud earns its place because it records the whole scene, not only the points someone thought to measure — questions that surface weeks later can often be answered from the cloud without returning to a site that is back in production.
Frequently asked questions
What is the difference between an as-built survey and a set-out survey?
They sit at opposite ends of construction. A set-out (or set-out) survey establishes the design position on the ground before work begins, telling the builder where to build. An as-built survey measures what was actually built after construction is complete and records where everything ended up. One guides construction; the other documents it. Many projects use ISS for both, which keeps the control network and datum consistent from set-out through to handover.
Can an as-built survey be done while the plant is operating?
Yes, with the right safety controls. Surveying an operating facility requires coordination with operations, adherence to isolation and permit-to-work systems, and live hazard awareness. 3D laser scanning is particularly valuable here because it captures comprehensive geometry in minutes per setup, minimising the time a surveyor spends in a hazardous area. Where the asset must be opened up — internal mill or kiln geometry, vessel internals — the as-built is captured inside a planned shutdown instead.
What datum and coordinate system do you deliver in?
The current national framework: GDA2020 with MGA2020 grid coordinates horizontally and AHD for elevation, so results tie cleanly into your design models and existing as-builts. On mine sites we routinely transform into your local mine grid as well. Supply existing control marks or a grid definition and we register to them; if none exist or they have been destroyed, we establish fresh control with GNSS and total station before measuring.
Does an as-built survey need a licensed surveyor?
Where the record must be legally defensible, certified, or tied to a registered control network — utility records under AS 5488, statutory mine survey work, evidence in a contract dispute — a licensed surveyor should supervise. ISS operates under qualified surveyors, so where your deliverable needs control-connected, certifiable accuracy that requirement is covered. For routine internal dimensional records the certification overhead is usually unnecessary, and we scope it to what the deliverable actually has to support.
How do you record underground services that are already buried?
Ideally they are surveyed while exposed during installation, which is why we recommend progressive as-built capture. Where services are already backfilled, we locate them with ground-penetrating radar and electromagnetic utility location, then survey the located positions and classify the confidence to AS 5488 quality levels. The standard is explicit that a buried, GPR-located service carries lower positional certainty than one picked up open in the trench — and the as-built records that distinction so nobody excavates on a false assumption.
How quickly do we get the as-built deliverables?
Field capture is fast; processing depends on scope. For a straightforward total-station as-built, drawings and tables typically follow within five business days. For a scan-to-BIM deliverable across a complex facility, registration and modelling take longer and we agree the turnaround at scoping. Where the as-built feeds a live decision — a shutdown retrofit, a clash check before a tie-in — we provide preliminary data on site and prioritise the critical elements first.
Ready to scope an as-built survey for your project or asset? Whether it is a single building handover, a buried-services record to AS 5488, or a full scan-to-BIM as-built of an operating plant, ISS delivers control-connected, standards-compliant documentation across Australia in the formats your team already uses. Call 0407 057 015 to discuss your scope, accuracy and datum, and request a fixed-price quote tailored to your project.