Spot Levels and Finished Floor Levels on a New Zealand Site Plan

Spot levels, contours and finished floor levels explain the vertical design of a property. They show whether the land rises or falls, how high a building will sit, where excavation or filling may be needed and how surface water should move around the site.

These levels are especially important for new houses, extensions, garages, retaining walls, steep driveways and properties affected by flooding. A site plan with accurate levels helps the council, designer, engineer and contractor understand how the proposed development relates to the existing ground.

Why Are Levels Shown on a Site Plan?

A conventional site plan shows where buildings and other features sit horizontally. Site levels add the third dimension by explaining their height and relationship to the ground.

Levels can help reviewers determine:

• how steep the property is;
• the elevation of the proposed building floor;
• how high the building will appear above natural ground;
• whether excavation or filling is required;
• how surface water will flow;
• whether water could enter the building;
• how the driveway connects to the road and garage;
• whether retaining walls are needed;
• how the proposal relates to neighbouring properties;
• whether flood-level requirements are satisfied; and
• whether planning height controls are met.

SIMPLI’s building-consent guidance says that a site plan for external or structural work may need to show finished floor levels, ground contours or levels and boundary dimensions. Where vehicle areas are affected, it should also show crossings, levels and driveway gradients.^[1]

Common Level Abbreviations

Abbreviations can vary between surveyors, councils and designers. Always check the drawing legend rather than assuming that every consultant uses identical notation.

What Is a Spot Level?

A spot level records the elevation at one specific point. It is normally shown beside a cross, dot, circle or other symbol linked to a numerical level.

For example, a label reading RL 24.62 means that the selected point has an elevation of 24.62 metres relative to the stated datum. It does not necessarily mean the point is 24.62 metres above the nearby road, ground or sea level.

Useful spot-level locations include:

• property corners;
• changes in ground slope;
• corners of the proposed building;
• door and garage thresholds;
• the top and bottom of retaining walls;
• driveway edges and changes in gradient;
• the road, kerb and footpath;
• stormwater pits and channels;
• existing building floors;
• the base of significant trees;
• high and low points; and
• areas where water may collect.

Several carefully positioned spot levels communicate the site more effectively than isolated values with no relationship to the proposed work.

Existing vs Proposed Spot Levels

A detailed site plan should distinguish existing levels from proposed finished levels. This allows the reviewer to understand how the development will change the land.

Existing levels may be shown with one symbol or line style, while proposed levels use another. The legend should explain the difference.

The values above are examples only. Actual project levels must come from appropriate site measurements and design work.

What Is a Finished Floor Level?

The finished floor level is the final elevation of the internal floor surface. For a concrete slab, it is generally associated with the upper surface of the completed slab or floor finish. For a suspended timber floor, it refers to the completed walking surface.

The FFL influences:

• building height;
• entry steps and accessible routes;
• garage and driveway transitions;
• foundation and subfloor design;
• cut-and-fill quantities;
• retaining-wall requirements;
• surface-water protection;
• cladding clearance above paving or soil;
• connection with existing floors; and
• flood compliance.

A label such as FFL 25.40 is incomplete unless the drawing also identifies the datum or reference used for that elevation.

Finished Floor Level Is Not the Same as Finished Ground Level

The finished floor and finished ground are two separate elevations. Their vertical difference helps protect the building from surface water and external moisture.

For example:

• FFL 25.40: internal finished floor;
• FGL 25.00: proposed finished ground outside; and
• difference: 400 mm between the two referenced elevations.

That difference does not automatically equal the visible foundation or cladding clearance because the construction build-up, slab edge, cladding type, paving and wall details must also be considered.

Building Code clause E2 requires buildings to resist the penetration and accumulation of external moisture.^[2] Applicable construction details therefore need to coordinate the floor level, adjoining ground and cladding clearances.

What Is a Datum?

A datum is the reference from which all elevations on the drawing are measured. LINZ explains that vertical datums define a reference surface for measuring elevations and depths consistently.^[3]

A project may use:

• New Zealand Vertical Datum 2016;
• a recognised local vertical datum;
• a council infrastructure datum;
• a surveyed benchmark;
• a temporary benchmark established for the project; or
• an assumed site datum, such as RL 100.00 at a stable reference point.

NZVD2016 is the official vertical datum used to define heights across New Zealand and its offshore islands.^[4] However, local and assumed datums are still found in council records, older surveys and individual building projects.

Relative Levels vs Levels Above Sea Level

Some site plans use an assumed datum because the project only needs consistent differences between points. For example, a surveyor may assign an existing manhole or survey mark the value RL 100.00.

Other projects require levels tied to an official or council datum, particularly when coordinating:

• minimum flood levels;
• public stormwater or wastewater connections;
• road and vehicle-crossing levels;
• subdivision infrastructure;
• regional flood models;
• adjoining developments; or
• large civil-engineering projects.

Do not describe an assumed level as “height above sea level” unless it has been correctly connected to an appropriate vertical datum.

What Are Contour Lines?

A contour is a line joining points of equal elevation. Contours provide a continuous picture of the site’s shape, while spot levels provide exact elevations at selected positions.

Contour spacing helps communicate slope:

• closely spaced contours usually indicate a steeper slope;
• widely spaced contours usually indicate gentler ground;
• closed contour patterns can identify high or low areas; and
• changing contour direction can indicate ridges, channels or depressions.

The plan should state the contour interval, such as 0.25 m, 0.50 m or 1.00 m. The appropriate interval depends on the property size, slope and required design detail.

Read the site-plan requirements for sloping properties in New Zealand for more information.

Spot Levels vs Contours

More complex sites generally benefit from both contours and strategically placed spot levels.

Natural Ground and Finished Ground

Natural ground generally refers to the ground surface before relevant excavation or filling. Finished ground is the proposed surface after construction and landscaping.

The distinction matters because planning rules may measure building height or height in relation to boundary from natural or existing ground rather than the newly created finished surface.

Natural-ground information can become difficult to establish when:

• the property was filled during an earlier development;
• retaining walls have altered the land;
• historic consent plans are incomplete;
• previous earthworks were not surveyed;
• the site has several terraces;
• the ground has been excavated beside an existing building; or
• the proposal includes substantial new filling.

Where planning compliance depends on natural ground, the council may require survey evidence, historic records or a clear explanation of how the reference surface was established.

Related guide: Height in relation to boundary on a New Zealand site plan.

How Levels Show Cut and Fill

Cut means removing soil to lower the ground. Fill means adding suitable material to raise it. Comparing existing and proposed levels allows the designer to identify where each is required.

A cut-and-fill plan may show:

• existing contours;
• proposed contours;
• existing and proposed spot levels;
• top and bottom of batters;
• retaining-wall locations;
• depth of cut or fill;
• earthworks extent;
• estimated earthworks volumes;
• temporary excavation areas; and
• surface-water controls.

Substantial earthworks may require civil, structural or geotechnical design beyond a standard drafted site plan.

Levels and Surface-Water Drainage

Building Code clause E1 requires buildings and sitework to protect people and other property from the adverse effects of surface water. It also requires appropriate surface-water disposal systems.^[5]

Spot levels and drainage arrows can demonstrate:

• that ground falls away from the building;
• where driveway runoff will travel;
• where channels or catch pits are required;
• whether water could collect beside a garage;
• how retaining-wall drainage connects;
• whether runoff could cross a neighbouring property;
• how an overland-flow path is maintained; and
• how proposed earthworks affect existing drainage.

A few drainage arrows without supporting levels may not prove that the design will work. The arrows, spot levels, pipe information and proposed grading should tell the same story.

For more detail, read the New Zealand stormwater and drainage site-plan guide.

Minimum Floor Levels and Building Code E1

E1/AS1 provides one Acceptable Solution for certain buildings and sites not considered likely to flood. Within its applicable scope, it includes minimum floor-level provisions and specifies relationships between floors, adjacent finished ground and road or site levels.^[6]

However, a commonly quoted floor-to-ground difference should not be treated as a universal design answer. The required FFL may be affected by:

• whether E1/AS1 applies to the site;
• known flood hazards;
• overland-flow paths;
• council flood models;
• district-plan minimum floor levels;
• road and kerb elevations;
• groundwater conditions;
• cladding and foundation construction;
• accessible-entry design; and
• an alternative Building Code compliance method.

Building Performance states that E1/AS1 applies to buildings and sitework that are not likely to flood, while E1/VM1 provides a method addressing surface-water runoff and secondary flow.^[7]

Finished Floor Levels on Flood-Prone Properties

When a property is affected by flooding or inundation, the proposed floor may need to be set above a council-defined or modelled flood level with an appropriate allowance.

The application may require:

• a topographical survey tied to the required datum;
• council flood-level information;
• the proposed FFL;
• existing and proposed ground levels;
• flood-depth information;
• overland-flow paths;
• cross-sections through the site;
• earthworks and fill design;
• stormwater calculations; and
• civil or hydraulic engineering.

The Building Act’s natural-hazard provisions require flood and other identified hazards to be considered during relevant building-consent decisions.^[8]

Christchurch City Council’s flood viewer, for example, provides predicted flood information and minimum floor-level requirements relating to Building Code clause E1.^[9] Other councils use their own flood models, datums and application processes.

Levels for Additions to Existing Buildings

An addition must coordinate with the existing building’s floor, foundations, doors, drainage and surrounding ground.

The site plan and architectural drawings may need to show:

• existing building FFL;
• proposed addition FFL;
• whether there will be an internal step;
• finished ground beside old and new walls;
• floor and foundation connections;
• roofwater disposal;
• door-threshold levels;
• accessible routes where applicable; and
• changes in building height.

Do not assume that the existing house floor shown on an old drawing matches its actual current elevation. Verification may be needed where the difference affects the proposed design.

Driveway and Garage Levels

A driveway needs to connect the public road or vehicle crossing to the garage or parking area without creating impractical gradients, vehicle-grounding problems or uncontrolled runoff.

Relevant levels can include:

• road-centre or road-crown level;
• top-of-kerb level;
• channel or gutter level;
• footpath edges;
• property-boundary level;
• vehicle-crossing levels;
• changes in driveway gradient;
• garage-threshold level;
• garage finished floor level; and
• channel-drain or catch-pit levels.

A steep or short driveway may require a longitudinal section rather than relying only on a top-down site plan. The section can show gradients and vertical transitions that help determine whether a vehicle will scrape at the road, crest or garage entrance.

How Is Driveway Gradient Calculated?

Gradient compares the vertical rise or fall with the horizontal distance.

For example, if a driveway rises 1 metre over a horizontal distance of 10 metres:

• ratio gradient: 1:10;
• percentage gradient: 10%; and
• approximate angle: 5.7 degrees.

The total average gradient does not show every local change. A driveway with an acceptable average can still have a sharp transition that causes a vehicle to scrape or sends water toward the garage.

There is no single driveway gradient suitable for every New Zealand property. Check the applicable council, vehicle-crossing and engineering standards.

Levels and Retaining Walls

Retaining-wall drawings normally need more information than a wall line on the site plan. Levels help explain why the wall is needed and how much soil it retains.

Show or obtain:

• existing ground on both sides;
• proposed finished ground on both sides;
• top-of-wall level;
• bottom or footing level;
• maximum retained height;
• wall length and alignment;
• distance from boundaries and buildings;
• surface-water direction;
• subsoil drainage; and
• batters or slopes above and below the wall.

The wall’s visible height is not necessarily the same as its retained height or total structural height.

Levels and Building Height

Proposed floor and ground levels can affect planning calculations for building height and height in relation to boundary. Raising a building pad may make drainage easier but could increase the building’s apparent or calculated height.

The design should coordinate:

• natural-ground information;
• proposed fill;
• finished floor level;
• floor-to-ceiling height;
• roof form and ridge height;
• boundary location;
• height-control planes; and
• elevations and cross-sections.

Do not adjust the floor level on one drawing without updating the elevations, sections, drainage design and height calculations.

Where Do Reliable Site Levels Come From?

Possible sources include:

• a topographical survey;
• a cadastral and level survey;
• a civil engineer’s survey;
• council infrastructure records;
• approved subdivision drawings;
• earlier building-consent plans;
• site measurements tied to a known benchmark; and
• verified as-built information.

Smartphone GPS, consumer mapping applications and estimated heights from aerial imagery are generally unsuitable for establishing consent-critical floor, flood, drainage or driveway levels.

Read when you need a survey before preparing a New Zealand site plan.

Site Plan vs Topographical Survey

A drafted site plan can incorporate survey information but does not replace a measured topographical survey where verified levels are required.

Common Level-Related Application Problems

• The site plan does not identify its datum.
• Different drawings use different datums.
• Existing and proposed levels are not distinguished.
• The FFL is shown without surrounding ground levels.
• Contours stop before reaching the relevant boundaries.
• Spot levels are too sparse to explain drainage.
• Drainage arrows conflict with the numerical levels.
• The garage FFL does not coordinate with the driveway.
• The floor level conflicts with architectural sections.
• Natural and finished ground are confused.
• Cut and fill are not identified.
• Retaining-wall heights cannot be calculated.
• Flood information uses a different datum.
• The building height was not updated after raising the FFL.
• Approximate online elevation data is presented as survey information.

A Practical Site-Level Design Process

1. Check the property: Review the title, council maps, flood information and available consent records.
2. Confirm the required accuracy: Ask the council or designer whether a topographical survey is necessary.
3. Select the datum: Use the required official, local or project datum and record it clearly.
4. Survey existing levels: Capture boundaries, buildings, roads, driveways, drainage and important ground changes.
5. Choose a preliminary FFL: Consider flood protection, earthworks, entries, drainage and building height.
6. Design finished ground: Grade the surrounding surfaces to manage water safely.
7. Coordinate the driveway: Check the road, crossing, gradient transitions and garage threshold.
8. Design earthworks: Identify cut, fill, retaining walls and batters.
9. Prepare sections: Show critical vertical relationships that cannot be understood from the site plan alone.
10. Coordinate all drawings: Ensure the site plan, floor plans, elevations, sections and engineering use matching values.
11. Set out construction: Transfer the approved levels to the site using reliable survey control.
12. Verify critical work: Arrange construction checks before errors become difficult to correct.

What to Provide When Ordering a Site Plan With Levels

• Property address and legal description.
• Current record of title and survey plan.
• Topographical or level survey.
• Required datum information.
• Proposed building dimensions and location.
• Proposed finished floor level, if already designed.
• Existing building floor levels.
• Driveway and garage information.
• Flood or minimum-floor-level advice.
• Stormwater and drainage plans.
• Retaining-wall or earthworks details.
• Any council request for information.

Frequently Asked Questions

What does RL mean on a New Zealand site plan?

RL usually means reduced level: an elevation measured relative to the drawing’s nominated datum. Check the plan legend because terminology can vary.

What does FFL mean?

FFL means finished floor level. It identifies the final elevation of the internal floor surface.

Is FFL measured above sea level?

Only if the levels are tied to an appropriate sea-level-based vertical datum. Some projects use an assumed local datum instead.

What is the difference between FFL and FGL?

FFL is the finished internal floor elevation. FGL is the finished external ground elevation after earthworks, paving or landscaping.

Does every site plan need contours?

No. A relatively level, uncomplicated site may be adequately explained with spot levels. Sloping, flood-prone or earthworks-heavy sites are more likely to require contours and a topographical survey.

Can I take my own spot levels?

Basic measurements may assist preliminary planning, but consent-critical floor, flood, drainage and construction levels should come from suitably accurate equipment and appropriately qualified professionals.

Can the floor level be changed during construction?

Do not change an approved FFL without consulting the designer and building-consent authority. The change may affect drainage, height, foundations, access, flood compliance and other approved documents.

Does NZ Site Plan provide topographical surveying?

No. NZ Site Plan prepares site plan drawings using information supplied by the client and relevant sources. A suitably qualified surveyor must obtain verified site levels when required.

Does NZ Site Plan decide the finished floor level?

No. The FFL should be established by the appropriate building designer, engineer or other qualified professional using project-specific survey, drainage, planning and flood information.

Final Site-Level Checklist

• Identify the datum used by the project.
• Confirm whether levels are official, local or assumed.
• Distinguish existing and proposed spot levels.
• Show the proposed FFL clearly.
• Show surrounding natural and finished ground.
• State the contour interval where contours are used.
• Coordinate surface-water arrows with numerical levels.
• Show road, kerb, crossing and garage levels.
• Identify cut, fill, retaining walls and batters.
• Check flood and minimum-floor-level requirements.
• Coordinate the FFL with elevations and building height.
• Use reliable survey information where accuracy matters.
• Ensure every drawing uses the same datum and current design levels.

This guide was reviewed in August 2026 and provides general information only. Floor-level, drainage, flood, earthworks and driveway requirements vary by property, council and project. Confirm current requirements with the relevant council and appropriately qualified surveying, architectural and engineering professionals before design or construction.

Official References

1. SIMPLI — Guide to Building Consent Applications
2. Building Performance — Building Code Clause E2 External Moisture
3. Toitū Te Whenua LINZ — Vertical Datums
4. Toitū Te Whenua LINZ — New Zealand Vertical Datum 2016
5. Building Performance — Building Code Clause E1 Surface Water
6. Building Performance — Acceptable Solution E1/AS1 and Verification Method E1/VM1
7. Building Performance — E1 Acceptable Solutions and Verification Methods
8. Building Performance — Natural-Hazard Decision-Making Process
9. Christchurch City Council — Flood and Floor-Level Viewer
10. Building Performance — Resilient Homes: Flooding Guide
11. Christchurch City Council — Residential Building-Consent Checksheet