Do I Need a Survey Before Building a Granny Flat?

30 Oct

Understand boundary surveys, site levels and construction set-out before committing to detailed plans.

Quick Facts – At a Glance

Not every enquiry needs a full survey: The right survey depends on the information needed for the next decision.

A fence may be in the wrong place: A registered cadastral surveyor can identify the legal boundary.

Levels affect design and cost: Slope, drainage, flood levels and retaining walls may need measured site information.

A survey is not a soil test: One measures the site; the other investigates the ground supporting the building.

Confirm the scope: A feature survey does not automatically verify legal boundaries or buried services.

Indicative guidance only: the requirements and costs must be confirmed for the actual property and design.

The useful question is what information the site needs

Not every granny flat needs a full survey at the very first enquiry stage. However, surveys become very important when the design depends on accurate boundaries, setbacks, levels, flood information, retaining walls or underground infrastructure.

The useful question is therefore not simply “Do I need a survey?” but “What type of survey information does this property need, and at what stage?” Getting that answer right can avoid designing a granny flat in the wrong position.

Boundary identification

Your fence is not necessarily the legal property boundary. If a design relies on a tight clearance, a difference of a few hundred millimetres can affect whether it complies.

A cadastral survey is the type of survey used to define legal boundaries. In Queensland it must be undertaken by an appropriately registered cadastral surveyor. Ask whether boundary identification is included rather than assuming it comes with every site plan.

Feature and level surveys

A feature and level survey records site features and ground levels. It can help the designer place the building, plan drainage and estimate earthworks. It is particularly useful on sloping blocks, flood-affected properties or sites with retaining walls.

A feature survey may show boundaries plotted from existing records without re-establishing them on the ground. Likewise, a title survey plan normally does not provide land contours. Ask for the combination of boundary and level work the project actually needs.

Online aerial images and broad contour maps are useful for preliminary screening. They should not be treated as precise construction measurements. Where a required floor level is involved, the survey and the designer’s levels must use a suitable common reference.

Construction set-out and clearance checks

Before foundations are constructed, the approved building footprint must be set out correctly on the land. Construction set-out places the building; it does not decide whether the proposed use or design is approved.

The certifier may also need evidence that the building is in the approved position. Agree who will provide the necessary survey or inspection information before the relevant construction stage.

Survey information and underground services

A survey may record visible service features, but it does not automatically locate every buried sewer, water pipe or cable. A utility locator may be needed where the building or footings could conflict with underground assets.

Tell the surveyor, locator and designer what information is needed so their plans can be coordinated. Avoid paying for one investigation and discovering it does not answer the key question.

What to check in each council area

The council checks below sit alongside the common building requirements. A planning scheme is the council’s rulebook; its zones and precincts identify areas with different controls.

Brisbane

A siting-referral application calls for dimensioned plans, contours, ground levels and building heights. Tight small-lot setbacks or a required flood floor level can make accurate survey information particularly important. The survey scope must suit the issue being assessed.

Moreton Bay

Confirm the relevant zone and precinct before ordering the final siting plan. Some controls distinguish walls from roof projections and use lot dimensions or depth. Ask whether legal boundaries and site levels both need verification for the proposed design.

Ipswich

Check the current City Plan controls, building position and relevant flood or difficult-topography mapping. The designer and certifier should identify whether boundary identification, measured levels or a construction set-out survey is needed. An old general site sketch may not answer those questions.

Logan

Use the property report to identify constraints, then establish the measured information needed for the design. Sloping or flood-affected sites can need accurate levels as well as boundaries. The required scope follows the site and approval pathway, rather than a single survey rule for every Logan property.

Redland

Council’s referral guidance calls for dimensions, contours, ground levels, heights and finished floor levels. Where a siting departure or hazard is involved, have the survey brief cover the measurements needed for assessment. A fence-based sketch may be inadequate.

When to arrange the work and what it may cost

Start with preliminary feasibility. Once the project appears worth pursuing, arrange the necessary survey before the design depends on an uncertain boundary or level. A difficult site may need that work earlier.

Ask for a written quote describing boundary identification, features, levels, deliverables and any later set-out visit. Price varies with the lot, access, vegetation, records and scope, so there is no single survey price suitable for every granny flat.

A soil test investigates foundation conditions. A survey measures the land. The project may need both, and an existing report should be reviewed before it is reused.

Request Your Free Site Assessment Report

Start with Hive Small Homes’ Free Site Assessment Report. This preliminary desktop review identifies potential setbacks, mapped underground infrastructure and easements, overlays and other feasibility issues, subject to verification. It helps identify what needs further investigation before detailed plans or specialist work.

The report is not a boundary survey, on-site utility location, soil investigation or formal approval. Necessary specialist investigations are separate. Hive coordinates feasibility, design, engineering and approvals; construction contracts are directly between homeowners and independent QBCC-licensed builders.

Click here to request your Free Site Assessment Report

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What Soil Tests and Engineering Are Required for a Granny Flat?

Granny Flats on Sloping Blocks

Easements and Granny Flats

Important Information

This article is general information, not building, planning, energy assessment, engineering or legal advice. Eligibility, floor area, approval pathways, specifications and pricing must be confirmed for each project by the relevant professionals. Published October 2026.