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Site set-out and survey: residential pre-construction guide

Site set-out for residential builds: registered surveyor scope, boundary pegs, AHD vs assumed datum, profile boards, TBM, and state-by-state requirements.

By Dan Waring. Last updated 10 May 2026. Verified 10 May 2026.

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TL;DR

Site set-out transfers approved plans onto the physical lot before a slab or footing goes in. A registered surveyor must perform any work that involves a boundary or establishes a building offset from one: it is an offence under state surveying legislation for anyone else to do it. Budget $1,500 to $3,500 ex-GST for a standard residential set-out on a suburban block; complex or sloping sites push higher. The top delay killer is calling the surveyor after the slab form is up: they need to be booked before formwork begins, because a mis-set building will fail the council hold-point inspection and the cost to jack and reposition is orders of magnitude higher than the survey fee. If the site uses an assumed datum rather than AHD, confirm the assumed RL with the engineer before the surveyor sets the temporary benchmark.

When you do this

Site set-out happens after building approval is issued and before any formwork, footing excavation, or slab preparation begins. The sequence in a standard residential build:

  1. DA or CDC granted, Construction Certificate (CC) or building permit issued
  2. Site establishment (fencing, amenities, services locates)
  3. Registered surveyor on site: boundary re-establishment and set-out
  4. Earthworks or pad prep (if required)
  5. Footing excavation, formwork, inspections, pour

The set-out survey must happen before step 4 on any site where a footing or slab is placed within a defined setback distance from a boundary. Getting the sequence wrong is not a minor paperwork problem: it is a structural problem.

Who’s involved

RoleResponsibility
Registered surveyor (cadastral)Boundary re-establishment, set-out of building corners, profile board setup, temporary benchmark, set-out certificate or Form 12
Structural or geotechnical engineerSpecifies finished floor level (FFL) and reduced level (RL) datum; often the source of the assumed datum or AHD tie
BuilderBooks the surveyor, provides approved plans, coordinates earthworks sequence; must not proceed past hold-point without the surveyor’s sign-off
Private certifier or councilHolds the slab inspection point pending the surveyor’s certificate (state-specific, see below)

Note: building surveyors (who issue building permits and conduct mandatory inspections in some states) are not the same as registered land surveyors. A building surveyor is not legally authorised to perform cadastral boundary work or issue a set-out certificate.

Only a registered land surveyor is authorised to survey involving property boundaries or set out a building at a stated offset from a boundary. This is a statutory offence in every Australian state and territory:

  • NSW: Surveying and Spatial Information Act 2002 (NSW). The Act mandates a registered surveyor for any cadastral survey; the Surveying and Spatial Information Regulation 2017 sets the practice standards (verified 2026-05-10, BOSSI NSW).
  • VIC: Surveying Act 2004 (VIC). The Surveyors Registration Board of Victoria (SRBV) registers cadastral surveyors; only a licensed surveyor may determine or mark the legal boundaries of property (verified 2026-05-10, SRBV).
  • QLD: Surveyors Act 2003 (QLD). Only a registered cadastral surveyor may perform a boundary survey, place a survey mark that defines a property boundary, or certify plans for lodgement with the Titles Registry (verified 2026-05-10, Surveyors Board of Queensland).
  • WA: Licensed Surveyors Act 1909 (WA). Any person carrying out land surveying must hold a current practising certificate from the Land Surveyors Licensing Board of WA (verified 2026-05-10, LSLB WA).

Mutual recognition (Mutual Recognition Act 1992 (Cth)) allows a surveyor registered in one state to apply for registration in another without repeating all examinations, but they must be registered in the destination state before practising there.

Steps

1. Engage the surveyor before formwork

Book the surveyor as soon as the Construction Certificate or building permit is issued, not after the slab form is set. The surveyor needs:

  • Approved architectural plans (dimensioned floor plan showing setbacks and levels)
  • The Construction Certificate or building permit number
  • Engineer’s footing and slab details, including the finished floor level (FFL) and site datum reference (AHD or assumed)
  • Title details (lot and deposited plan number)

Allow two to five working days lead time for a suburban site, longer for complex or regional sites.

2. Boundary re-establishment

Before any building corners are set, the surveyor re-establishes the legal boundaries of the lot. This involves:

  • Searching the deposited plan and any existing survey marks (pegs, pins, concrete blocks) from prior surveys
  • Using GPS receivers and total-station instruments to millimetre-accurate GPS and total-station instruments to locate or replace all corner pegs
  • Placing or replacing boundary pegs at each corner

It is illegal to remove or reposition a boundary peg. Builders who find a peg in the way of formwork must contact the surveyor: the peg cannot be pulled.

The surveyor’s boundary re-establishment is recorded and lodged with the relevant state spatial authority (NSW Spatial Services, Land Use Victoria, Titles Queensland, Landgate WA, etc.).

3. Establish the site benchmark (TBM)

A temporary benchmark (TBM) is a fixed reference point with a known elevation, placed at a stable location on or near the site, used to control all height measurements throughout the build. The TBM is typically:

  • A nail in a concrete kerb, the top of an existing concrete structure, or a steel pin set in the ground
  • Placed outside the footprint of the excavation and all earthworks disturbance areas
  • Referenced to either AHD or an assumed datum

The TBM must survive for the full build programme. Builders should protect it from earthworks plant. If a TBM is disturbed, the surveyor must be called back to re-establish it before any level-dependent work continues.

4. AHD versus assumed datum: know the difference

Australian Height Datum (AHD) is the official national vertical datum, adopted by the National Mapping Council in 1971 (verified 2026-05-10, Geoscience Australia). AHD is referenced to the mean sea level of 32 tide gauge sites measured between 1966 and 1968 and adjusted across approximately 177,000 km of levelling observations. On AHD, a point at zero metres is effectively at mean sea level; points above are positive, points below are negative.

Assumed datum is a local datum used when an AHD-tied control mark is not available or practical for a small residential site. The surveyor assigns an arbitrary elevation to the site benchmark, such as RL 10.000 m, and all levels on site are relative to that assumed point. The assumed RL has no meaning outside the site.

Consequences for builders:

ScenarioRisk if confused
Council requires minimum FFL above AHD flood levelAn assumed datum will not satisfy the flood level requirement; AHD tie mandatory
Engineer specifies FFL relative to AHDIf the surveyor uses assumed datum, the FFL will be offset by whatever the assumed RL was set at
No AHD tie-in on the drawingsAsk the engineer explicitly before the survey; do not proceed on ambiguous level references

Most metropolitan sites in NSW, VIC, and QLD require AHD for council flooding and stormwater compliance. Always confirm with the certifier what datum is required by the consent conditions.

5. Set out building corners and offset pegs

Once the boundaries are established and the TBM set, the surveyor marks the building footprint. The process:

  1. Calculate control points: the surveyor pre-calculates the exact coordinates of each building corner from the approved plan dimensions and the re-established boundaries.
  2. Set corner marks: physical marks (paint, pegs, or nails in concrete) placed at each corner of the building footprint.
  3. Set offset pegs: because the initial corner marks will be destroyed when excavation and formwork begin, the surveyor places offset pegs a fixed distance outside each corner. Offset pegs survive earthworks and allow the builder to re-establish the building corners at any point in construction by measuring back from the known offsets.
  4. Quality check: the surveyor verifies that the set-out matches the approved plan dimensions and that setbacks to all boundaries comply with council consent conditions.
  5. Provide set-out sketch: a digitised or hand-drawn sketch showing all marked points, offsets, and the TBM location, given to the builder.

6. Profile boards

Profile boards (also known as batter boards in some states) are horizontal boards nailed between stakes, positioned outside the building footprint and aligned with the building corners. They allow the builder to:

  • Stretch string lines between profile boards to re-establish wall lines and footing positions at any time during construction
  • Set footing trench widths by marking footing lines on the profile board
  • Control excavation depth by measuring down from the string line

The surveyor sets the profile board height and alignment. The boards must be at a stable height that will not move during construction, typically set at a fixed elevation above the finished floor level or footing top. The profile board stakes must be outside the zone of earthworks disturbance.

7. Certificate sign-off (state-specific)

The set-out certificate or building location certificate is the formal output of the set-out survey, confirming to the certifier that the building has been located on site per the approved plans.

StateCertificate typeWhen required
NSWSet-Out CertificateRequired before slab pour at the certifier’s discretion; the CC conditions or the private certifier will specify if mandatory
QLDForm 12 (Building Location Certificate)Mandatory; issued by a registered cadastral surveyor after set-out is complete; required for the certifier’s pre-slab inspection. Only a registered cadastral surveyor with cadastral endorsement can issue it (verified 2026-05-10, Surveyors Board of Queensland / Sonto)
VICAs specified in the building permit conditionsThe private building surveyor holds the footing inspection point; a set-out plan from a licensed surveyor may be required by permit conditions
WASurvey report or location planBuilding licence conditions specify requirements; council or the private certifier will advise

Check the CC or building permit conditions on the day of issue. Do not assume the set-out is advisory only.

8. Post-slab or post-frame as-built survey

An as-built survey confirms that what was built matches the approved plans and sits within the consented boundaries. Common trigger points for a post-construction survey:

  • After slab pour: confirm the slab is in the right location before the frame goes up. Some certifiers require this as a mandatory hold point.
  • At frame complete: confirm wall setbacks and building height comply with consent conditions.
  • At practical completion (PC): for the final occupancy certificate (OC) or certificate of occupancy, some councils require a final as-built survey certifying setbacks, boundary clearances, and finished floor levels.

A slab in the wrong location can be a total loss. An as-built at slab stage is cheap insurance relative to demolishing and repouding a mis-set slab.

Tolerances and acceptance

Set-out tolerances apply to how accurately the surveyor’s marks are placed relative to the design. These are survey-measurement tolerances, not construction tolerances.

ElementTypical survey tolerance
Corner peg position (plan accuracy)10 to 20 mm of design position for residential set-out using GPS and total station
Reduced level at TBM and set-out points±5 mm of design RL using spirit levelling or digital level
Profile board alignmentSet by surveyor; builder tolerance for string line offset from profile board mark is construction-specific

Construction tolerances for the finished slab, footing, and wall positions are separate from the set-out tolerances and are governed by the HIA Guide to Materials and Workmanship and state guides. Workmanship tolerances for finished slab level and position relative to set-out are: per current HIA Guide to Materials and Workmanship. Verified numerical value pending HIA member access. [HIA-074]

Documents needed

  • Approved architectural plans (CC or building permit set)
  • Engineer’s details (footing type, FFL, datum reference)
  • Title/deposited plan details (lot number, DP/LP/SP number)
  • Surveyor’s set-out certificate or Form 12 (as applicable by state)
  • Set-out sketch from surveyor (showing offset pegs, TBM, corner marks)
  • Consent conditions from the DA or CDC (datum requirements, mandatory as-built hold points)
  • AS 1726:2017 (geotechnical site investigation standard, relevant if the set-out uncovers soil anomalies not captured in the geotech report)

Common holds

  • Surveyor booked after formwork is up. If the slab form is already set when the surveyor arrives and it is in the wrong location, the form must be stripped and reset. This has happened. Book the surveyor before any formwork starts.
  • Boundary peg pulled to make way for formwork. Illegal. Boundary pegs must not be removed without the surveyor’s instruction. If the formwork design clashes with a peg position, the surveyor must be called to advise on offset marking.
  • AHD required but assumed datum used. If the consent conditions specify a minimum FFL relative to AHD and the surveyor worked from an assumed datum, the levels are unverified. The certifier will require an AHD tie-in before signing off.
  • No Form 12 or set-out certificate before inspection. In QLD, the pre-slab inspection cannot proceed without a valid Form 12. In NSW, the certifier may hold the inspection pending the certificate. Sort this before the pour is scheduled.
  • TBM disturbed by earthworks. All subsequent levels are unreliable until the TBM is re-established. Do not pour any concrete referenced to a disturbed TBM.
  • Geotech context missed. AS 1726:2017 governs geotechnical site investigations. If the set-out survey reveals unexpected fill, soft ground, or site conditions not captured in the original geotech report, stop and engage the geotechnical engineer before proceeding. A changed ground profile may alter the footing design.

References

See also

Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.

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