When planning a renovation, new home, extension, pool, retaining wall or small development, one of the first professional documents requested may be a land survey. The difficulty is that the word “survey” can describe several different services, each designed to answer a different question.

Two of the most commonly confused services are a boundary survey and a detail survey.

A boundary survey is concerned with the legal location of the property boundaries. A detail survey records the physical features, structures and levels on the land so that an architect, building designer, planner or engineer can understand the site and prepare plans.

The difference is important. A detailed drawing that shows a house, fence and retaining wall does not necessarily establish the legal property boundary. Similarly, a survey that marks the property corners may not provide the contours, floor levels, trees, services and adjoining features needed for design.

Understanding what each survey does can help homeowners commission the right work and give designers confidence that the information they are using is suitable for the project.

What is a boundary survey?

“Boundary survey” is a common public term for a cadastral survey that identifies or marks an existing property boundary. In Queensland, this is generally called an identification survey.

Its purpose is to determine where the legal boundaries of a parcel are located on the ground.

The cadastral surveyor investigates registered survey plans, title information, existing survey marks, surrounding surveys and physical occupation such as fences, walls and buildings. The surveyor then assesses that evidence and applies cadastral surveying principles to reinstate the boundaries.

This is more involved than measuring from a fence, copying dimensions from an old plan or locating coordinates on an online map.

Queensland Government guidance explains that property boundaries are defined through the cadastral survey system and survey marks. They are not simply defined by GPS coordinates. Surveys that identify existing property boundaries are cadastral surveys and can only be carried out by surveyors who are appropriately registered to perform cadastral work in Queensland.

Depending on the agreed scope, a boundary survey may:

• mark or reference property corners
• identify the relationship between fences and legal boundaries
• measure buildings, walls or other structures near a boundary
• identify possible encroachments
• show offsets between improvements and boundaries
• produce an identification survey plan or report
• provide information for fencing, setbacks or neighbour discussions

A boundary survey usually identifies an existing legal boundary. It does not create a new boundary unless it forms part of another cadastral process, such as a subdivision or boundary realignment.

What is a detail survey?

A detail survey records the physical characteristics of a property and its immediate surroundings.

It may also be described as a detail and contour survey, feature and level survey, site survey or topographic survey.

The purpose of a detail survey is normally to provide measured base information for design and assessment. It helps the design team understand what is currently on the land, how the land slopes and how the site relates to nearby properties, roads and infrastructure.

Queensland Government guidance describes detail, feature and contour surveys as surveys used to obtain the locations and levels of features on the land for building and construction design. It also cautions that the property boundaries shown on these surveys may have been plotted from existing survey records rather than verified on the ground.

The information included in a detail survey depends on the project brief, but it commonly shows:

• existing buildings and structures
• roof outlines, eaves and floor levels
• fences, walls and retaining walls
• driveways, paths and paved areas
• spot levels and contours
• significant trees and vegetation
• visible services and service structures
• kerbs, channels, footpaths and road levels
• neighbouring buildings near the site
• adjoining roof heights, windows or floor levels where relevant
• easements or title information, when included in the scope
• the north point, scale and property description

This information allows architects, building designers and engineers to position proposed work, assess site levels, plan drainage, coordinate access and consider the relationship between the development and neighbouring properties.

A detail survey is focused on the physical condition of the site. It is not automatically a legal boundary determination.

The most important distinction

The simplest way to understand the difference is:

A boundary survey answers: Where is the legal property boundary?

A detail survey answers: What is on and around the site, and at what level?

This distinction is particularly important when a detail survey shows a boundary line.

That line may have been:

• copied or calculated from registered survey information
• obtained from digital cadastral mapping
• positioned approximately in relation to site features
• reinstated through a cadastral identification survey

These methods do not provide the same level of boundary certainty.

Homeowners and designers should not assume that every boundary line shown on a site plan has been legally identified on the ground. The survey brief should clearly state whether the relevant boundaries are to be cadastrally reinstated and whether boundary corners need to be marked.

Queensland’s Cadastral Survey Requirements treat identification surveys as cadastral surveys and contain standards for measurement, boundary reinstatement, plan presentation, marking and survey reporting.

Boundary survey and detail survey compared

Question	Boundary survey	Detail survey
Main purpose	Identify existing legal property boundaries	Record site features, structures and levels
Common Queensland term	Identification survey	Detail and contour survey or feature and level survey
Typical users	Owners, builders, fencing contractors, certifiers and designers	Architects, designers, engineers, planners and landscape architects
Typical output	Boundary marks, identification plan or survey report	Existing conditions plan with levels and features
Establishes the legal boundary	Yes, when undertaken as a cadastral identification survey	Not necessarily
Shows contours and site levels	Only when included in the scope	Usually
Shows buildings and improvements	Usually where relevant to the boundary	Usually in greater detail for design
Common reason for commissioning	Fence, setback, encroachment or boundary uncertainty	Renovation, new building, planning or engineering design

When might you need a boundary survey?

Building close to a boundary

A proposed garage, extension, deck, carport, retaining wall or pool may be designed close to a side or rear boundary.

In these situations, small differences in the assumed boundary position can affect setbacks, access, fire separation, construction tolerances and the overall design.

A boundary survey allows the designer to work from an identified cadastral boundary rather than relying on a fence that may be offset, irregular or incorrectly positioned.

Constructing or replacing a fence

An existing fence provides evidence of how the land has been occupied, but it is not conclusive proof of the legal boundary.

Fences may have been built inside a property, placed around vegetation or constructed without a cadastral survey. Some older fences may also have been replaced in a slightly different position.

A boundary survey can identify the legal boundary before a new fence is constructed. The surveyor identifies the boundary, but legal questions about fencing contributions, ownership or liability may require separate advice.

Investigating an encroachment

An encroachment may involve a building, roof, wall, footing, driveway or other improvement crossing a legal property boundary.

Where an encroachment is suspected, a cadastral survey can measure the relationship between the improvement and the reinstated boundary.

Aerial imagery, council mapping and online property maps are useful for general investigation, but they should not be relied on to determine whether an encroachment legally exists.

Buying or redeveloping an older property

Fences, retaining walls and buildings on established properties may have changed several times since the original subdivision.

A boundary survey can reveal discrepancies that may affect redevelopment, access, proposed setbacks or the location of new structures.

It may be particularly useful where the property is narrow, irregularly shaped or surrounded by older development.

Replacing missing boundary pegs

A missing peg should not be replaced by estimating its position from a tape measurement, phone application or digital map.

The position of a boundary corner needs to be determined from cadastral survey evidence. A registered cadastral surveyor may need to search for existing marks, compare surrounding surveys and assess the available evidence before reinstating the corner.

When might you need a detail survey?

Designing a new home

A new home design may depend on site levels, road access, drainage direction, retaining requirements, existing services and nearby buildings.

A detail and contour survey provides a measured base plan that the designer can use when preparing the building layout and assessing how the home will respond to the land.

Planning an extension or renovation

For an extension, the designer may need the existing house footprint, floor levels, roof form, eaves, windows, retaining walls and the position of nearby structures.

This information allows the proposed work to be accurately connected to the existing building.

Preparing engineering designs

Civil and structural engineers may need accurate levels and site features for:

• stormwater drainage
• retaining wall design
• driveways and vehicle access
• earthworks
• finished floor levels
• site grading
• infrastructure connections

The survey should be briefed around the engineer’s actual information requirements. A general detail survey may not include every level or feature needed for specialist engineering design.

Assessing planning and design constraints

A planner or designer may use the survey to assess setbacks, site cover, building height, access, vegetation, privacy and the relationship between the proposed work and nearby development.

The detail survey does not replace other investigations. Depending on the project, separate flood information, service locating, geotechnical testing, arborist advice or planning searches may still be required.

When do you need both surveys?

Many residential projects need a combined boundary and detail survey.

For example, an architect designing an extension close to a side boundary may need:

• the side and rear boundaries cadastrally reinstated
• the existing house and floor levels
• fences and retaining walls
• nearby trees and visible services
• the position of the adjoining house
• contours and drainage features
• accurate offsets between the house and boundaries

Combining the work gives the designer a coordinated base plan containing both legal boundary information and measured site detail.

A combined survey is often appropriate where:

• the proposed building is close to a boundary
• the property is narrow or irregular
• the fences do not appear consistent with title dimensions
• retaining walls are located along the boundaries
• an existing building may encroach
• a setback variation may be required
• demolition and rebuilding are proposed
• the design depends on precise site coverage or building location

Not every project requires every property corner to be marked. The required scope depends on the location of the proposed work, the risks involved and the information needed by the designer, certifier or approval authority.

Which survey should be completed first?

Where both types of information are required, it is often practical to commission the boundary and detail components together.

This gives the design team one coordinated survey and reduces the risk of design work being based on an unverified boundary line.

When the surveys are commissioned separately, important boundary questions should generally be resolved before the design becomes highly developed. Moving a building after planning drawings, engineering designs or consultant reports have been prepared can create unnecessary rework.

A designer may use title information or online mapping during an early feasibility assessment. However, preliminary information should not be treated as a substitute for a cadastral survey where the design depends on the exact position of the boundary.

How to prepare a useful survey brief

Rather than simply requesting “a survey”, explain what is being designed and how close the proposed work may be to a boundary.

A useful survey brief should identify:

• the property address and lot on plan description
• the type of project
• the relevant boundaries
• whether boundary corners need to be marked
• known concerns about fences or encroachments
• the contours or level information required
• the site features that must be recorded
• whether adjoining buildings or windows are required
• the preferred drawing and digital file formats
• any requirements provided by the architect, engineer or certifier

Designers should provide a marked-up plan where possible. This can clearly identify the required extent of the survey and reduce the likelihood that important information will be omitted.

Questions to ask before relying on a survey

Before the design progresses, homeowners and designers should confirm:

1. Have the relevant property boundaries been cadastrally identified?
2. Are any boundary lines shown for general reference only?
3. Were the boundary corners marked or referenced?
4. Does the plan include the features and levels needed for the design?
5. Is there enough adjoining information for planning and privacy assessment?
6. Are easements shown, and has a current title search been reviewed?
7. Does the designer or engineer need additional information?
8. Does the survey reflect the current physical condition of the property?

A registered cadastral plan remains part of the land records until it is replaced through a later registered survey. However, the physical condition of a site may change as fences, buildings, vegetation, retaining walls and services are altered.

Choosing the right survey

Choose a boundary survey when the main issue is the legal location of the property boundaries.

Choose a detail survey when the main issue is obtaining site features and levels for design.

Choose a combined boundary and detail survey when the proposed work is close to a boundary, the site is constrained or the design depends on both boundary certainty and accurate existing conditions.

The scope should match the decisions that will be made from the survey. Clear instructions at the beginning can help avoid unnecessary work while ensuring homeowners and designers receive information that is appropriate for the project.