TL;DR
A formwork survey is a pre-pour engineering survey that verifies the position, level, verticality and dimensions of erected formwork against the design before concrete is placed. Because concrete is unforgiving once set, the survey confirms the mould is correct while errors are still cheap to fix. ISS performs formwork surveys with total stations and laser scanners to tolerances of 3 mm to 10 mm, referenced to GDA2020/MGA2020 horizontally and AHD for levels.
Key takeaways
- A formwork survey is checked before the pour; an as-built survey is checked after it. The whole value of a formwork survey is catching the error while it can still be moved by hand.
- Typical formwork tolerances under AS 3610.1 and AS 3600 sit at +/- 3 mm for column and starter-bar positions, +/- 5 mm for slab edges and soffit levels, and 1:300 (about 3 mm/m) for wall and column verticality.
- ISS surveys reference horizontal position to GDA2020/MGA2020 and levels to AHD, tied to the project control network so formwork, steel and services all share one datum.
- Equipment is a Leica TS16 or Trimble S7 total station for setout points and a Leica RTC360 or FARO Focus laser scanner for full soffit, edge and penetration verification on complex pours.
- A formwork survey for a typical suspended slab in an Australian city costs roughly AUD 1,200-3,500; a rework or re-pour from an uncorrected error costs many times that, plus program delay.
What is a formwork survey?
Definition: A formwork survey is a survey carried out on erected formwork prior to a concrete pour to confirm that its position, alignment, level, verticality and dimensions match the approved design within specified tolerances. It identifies and quantifies any deviation while the formwork can still be adjusted, preventing out-of-tolerance concrete.
Formwork is the temporary mould that holds wet concrete in shape until it cures. Whatever position, level and shape the formwork is in at the moment of the pour becomes permanent. If a column box is 20 mm off line, the cured column is 20 mm off line — and the only remedies are grinding, packing, structural assessment or demolition, all of which are expensive and slow.
The formwork survey exists to break that risk. By measuring the formwork against the design before any concrete arrives, the surveyor turns a potential structural defect into a five-minute carpentry adjustment. It is one of the highest-leverage checks on a concrete job: a small, fast survey that protects a large, irreversible commitment of material and labour.
A formwork survey is sometimes called a pre-pour survey, a formwork check survey, or setout verification. On large or complex jobs it is run hand in hand with the original setout — the surveyor sets out the formwork lines, the carpenters build to them, and the formwork survey is the independent confirmation that the build matches the marks before the pour proceeds.
Key facts about formwork surveys
- The survey is timed for the gap between formwork completion and concrete delivery — often a single window of a few hours before a booked pour, which is why turnaround speed matters.
- AS 3610.1:2010 (Formwork for concrete) and AS 3600:2018 (Concrete structures) govern formwork tolerances and finished-position tolerances respectively in Australia.
- Verticality (plumb) of columns and walls is commonly specified as 1:300 of height, equating to about 3 mm per metre — roughly 9 mm over a standard 3 m storey.
- A modern terrestrial laser scanner captures up to 2 million points per second, allowing an entire slab soffit, edge form and every penetration to be verified in one scan rather than dozens of discrete total-station shots.
- Formwork position is tied to the same control network used for the whole structure, so a deviation found at formwork stage is measured in the project's own coordinates (GDA2020/MGA2020 and AHD), not a local guess.
How a formwork survey works
A formwork survey follows five steps, from setting up on control to issuing the pre-pour clearance. On a typical suspended slab it takes 1-3 hours on site plus a short reporting window.
The formwork survey process
Set up on control: The surveyor occupies known control points and back-sights to verify the instrument is correctly oriented in the project datum. Levels are tied to AHD via the site benchmark. This step guarantees the formwork is checked against the same reference as the rest of the structure.
Check horizontal position and dimensions: Using a total station, the surveyor measures formwork edges, column boxes, wall faces, kicker positions and penetration locations against the design coordinates. Out-of-position elements are flagged immediately to the formwork crew.
Check levels and verticality: Soffit and edge levels are measured against design RLs. Columns and walls are checked for plumb with the total station or a digital plumbing routine, assessed against the 1:300 verticality tolerance. On complex geometry, a laser scan captures the full surface for soffit flatness and edge straightness.
Verify embedments and penetrations: Cast-in items — anchor bolts, starter bars, ferrules, conduits, drainage penetrations and box-outs — are checked for position and projection. These are the most common and most costly things to get wrong, because they are easy to overlook and impossible to move after the pour.
Report and clear for pour: The surveyor issues a concise pre-pour report listing every element, its deviation and a pass/fail against tolerance. A pour proceeds only when all critical items are within tolerance or have a documented engineering acceptance.
Key point: The most valuable thing a formwork surveyor does is not measure quickly — it is to flag a deviation while the crew is still on site with tools in hand. A formwork survey delivered the morning after the pour is worthless. Field-to-report speed is the whole service.
Formwork survey vs as-built survey vs setout
A formwork survey is one of three related concrete-stage surveys. They differ mainly in timing and purpose.
| Aspect | Setout | Formwork Survey | As-Built Survey |
|---|---|---|---|
| Timing | Before formwork is built | After formwork built, before pour | After concrete is cured |
| Purpose | Mark where to build | Confirm formwork matches design | Record what was actually built |
| Can errors still be fixed cheaply? | Yes | Yes — adjust the formwork | No — grind, pack or demolish |
| Typical accuracy | 3-10 mm | 3-10 mm | 1-25 mm |
| Core deliverable | Marks and offsets on site | Pre-pour deviation report + clearance | Deviation report + as-built records |
| Best method | Total station | Total station + laser scanner | Laser scanner + total station |
The setout tells the carpenters where to build, the formwork survey confirms they built it correctly, and the as-built survey records the final outcome. Skipping the formwork survey means the first time anyone checks the geometry against design is the as-built — by which point any error is set in concrete.
Formwork survey tolerances in Australia
Tolerances come from the design documentation, AS 3610.1 (formwork) and AS 3600 (finished concrete). Project specifications often tighten these, particularly for precision elements such as crane bases, machine plinths and tilt-panel cast-in plates.
| Element | Typical position tolerance | Typical level/plumb tolerance |
|---|---|---|
| Column / wall verticality | +/- 3 mm | 1:300 of height (about 3 mm/m) |
| Column box position | +/- 3 mm | — |
| Slab edge / soffit | +/- 5 mm | +/- 5 mm (level) |
| Starter bars / dowels | +/- 3 mm | +/- 5 mm (projection) |
| Anchor bolts / hold-down bolts | +/- 1.5 to 3 mm | +/- 3 mm (projection) |
| Cast-in plates / ferrules | +/- 3 mm | +/- 3 mm |
| Penetrations / box-outs | +/- 5 to 10 mm | — |
| Floor flatness (slab soffit) | per AS 3610.1 surface class | per AS 3610.1 surface class |
Anchor bolts and cast-in plates carry the tightest tolerances because downstream steelwork and machinery are fabricated to fixed hole patterns. A bolt group 5 mm out of position can prevent a baseplate from dropping over its bolts, stopping an entire installation — which is why these items justify the closest scrutiny in any formwork survey.
Where is a formwork survey used?
Formwork surveys are used wherever a concrete element is structurally or dimensionally critical and the cost of getting it wrong is high.
Commercial and high-rise construction
Suspended slabs, core walls, columns and transfer structures are surveyed before each pour. On high-rise cores, a small verticality error compounds floor by floor, so plumb checks at formwork stage protect the alignment of the entire building.
Industrial and resources construction
Machine foundations, crane bases, conveyor footings, plinths and equipment bases are surveyed to the tightest tolerances on any site, because heavy rotating and lifting equipment is fabricated to fixed hole patterns. ISS routinely verifies cast-in anchor bolt groups before pour on mining and processing projects across WA, QLD and NSW.
Civil infrastructure
Bridge abutments, piers, headstocks, culverts and retaining walls are surveyed before pour to confirm position and level against design alignment, frequently as a contractual hold point before concrete can be ordered.
Precast and tilt-up
Precast bed setout and tilt-panel formwork are checked for panel dimensions, cast-in plate positions and lifting-insert locations before pour, because a misplaced insert can make a panel impossible to lift or fix safely.
Formwork survey equipment and specifications
ISS selects equipment to match the element. Discrete critical points — bolts, dowels, column lines — are best measured with a total station; full surfaces such as slab soffits and complex edge geometry are captured faster and more completely with a laser scanner.
| Specification | Total Station (setout points) | Laser Scanner (surface verification) |
|---|---|---|
| Typical accuracy | 1-3 mm | 1-3 mm at 10 m |
| Best for | Bolts, dowels, column lines, levels | Soffits, edges, penetrations, full geometry |
| Speed | Fast for discrete points | Millions of points per second |
| Example instruments | Leica TS16, Trimble S7 | Leica RTC360, FARO Focus, Trimble X7 |
| Datum | GDA2020/MGA2020, AHD | GDA2020/MGA2020, AHD |
For most slab and column pours a total station alone is sufficient. For congested industrial pours with dense reinforcement, multiple penetrations and tight cast-in tolerances, a laser scan provides a complete, defensible record of the formwork condition at the moment of clearance.
Frequently asked questions
What is a formwork survey?
A formwork survey is a pre-pour survey that verifies the position, level, verticality and dimensions of erected formwork against the approved design before concrete is placed. It identifies any deviation while the formwork can still be adjusted, preventing out-of-tolerance concrete. It is used on slabs, columns, walls, bridges and machine foundations across construction and industrial projects.
Why is a formwork survey done before the pour and not after?
Concrete is permanent once cured, so any geometric error becomes a structural defect that can only be fixed by grinding, packing or demolition. A formwork survey checks the geometry while the formwork is still adjustable, turning a costly re-pour into a quick carpentry correction. The window before a booked pour is the last cheap opportunity to be certain the structure will be built correctly.
How accurate is a formwork survey?
A formwork survey achieves 1-3 mm accuracy with a survey-grade total station or laser scanner. The tolerances it checks against are typically +/- 3 mm for columns and starter bars, +/- 5 mm for slab edges and levels, and 1:300 (about 3 mm/m) for verticality, per AS 3610.1 and AS 3600. Anchor bolts and cast-in plates are often held to +/- 1.5-3 mm.
How much does a formwork survey cost in Australia?
A formwork survey for a typical suspended slab or column pour costs roughly AUD 1,200-3,500 depending on size, complexity and access. Industrial pours with dense cast-in items and laser scanning sit at the higher end. The cost is small against the alternative: a single uncorrected error can mean grinding, structural assessment, re-pour and days of program delay.
What is the difference between a formwork survey and an as-built survey?
A formwork survey is performed before the pour to confirm the mould is correct while it can still be fixed. An as-built survey is performed after the concrete has cured to record what was actually built. The formwork survey prevents errors; the as-built survey documents the outcome. Both reference the same project datum, but only the formwork survey can stop a defect from being cast in.
How long does a formwork survey take?
Field work for a standard suspended slab takes 1-3 hours, with the pre-pour report issued the same day — usually within an hour or two so the pour is not delayed. A large industrial pour with laser scanning and many cast-in items may take half a day on site. Because surveys are scheduled against booked concrete deliveries, ISS prioritises fast field-to-report turnaround.
What to do next
A formwork survey is the cheapest insurance on a concrete job. For a fraction of a percent of the pour value, you confirm that what is about to become permanent is correct — before it is too late to change.
- Build the survey into your pour schedule. Book the formwork survey as a hold point before each critical pour, with enough lead time to correct any deviation found.
- Define the critical elements. Tell your surveyor which cast-in items, levels and tolerances matter most so the report focuses on what will actually stop your downstream works.
Call ISS on 0407 057 015 to discuss your formwork survey requirements. We provide pre-pour formwork surveys for slabs, columns, walls, bridges and machine foundations across Australia, referenced to GDA2020/MGA2020 and AHD, with fast same-day pre-pour clearance reports so your concrete program never waits on the survey.