Overview
Height-limited boundaries are used to define the vertical extent of a parcel and were previously referred to as stratum boundaries.
A height-limited boundary may be a surface that is mathematically described (r 12(2)(a)), or the surface or the bed of a water body (r 12(2)(b)). However, ground level is not an appropriate description for a height-limited boundary.
The vertical extent of a primary parcel must be defined by a height-limited boundary, where the extent is limited (r 38(2)).
The vertical extent of a non-primary parcel can be defined by a height-limited boundary or a permanent structure boundary (r 46(2)). However, only those non-primary parcels specified in r 56(1) may be defined by PSB’s.
The same boundary cannot be both a height-limited boundary and a permanent structure boundary.
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Mathematical description of a height-limited boundary
A height-limited boundary that is mathematically described must have at least one point with a reduced level (r 12(2)(a)). However, inclusion of a reduced level alone is not sufficient to create a height-limited boundary. The boundary surface must also be mathematically described.
Rule 12(2)(a) is not prescriptive as to how a boundary surface is mathematically described. This allows for horizontal planes, sloped (angled) planes, and other shapes such as cylinders to be used as height-limited boundaries.
Height-limited boundaries for horizontal planes may be defined by cross section plan graphics showing the relevant boundaries as horizontal lines with reduced levels as appropriate (see Figure 1 below). Other surfaces such as sloped planes may need to be described by mathematical formulae in addition to reduced levels. Complicated boundary forms such as cylinders are likely to be rare, and if such boundary forms are used, advice should be sought from LINZ if required.
Figure 1: Height-limited boundaries with reduced levels
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Vertical datum requirements
All reduced levels in a survey must be in terms of a single official vertical datum (r 18(1)). NZ Vertical Datum 2016 (NZVD2016) is the only official vertical datum that can be used for cadastral surveys (Schedule 5 CSR 2021), unless exempted by the CSR 2021 or by dispensation.
Rule 60 CSR 2021 requires that all new boundary points on a non-primary parcel must comply with the vertical datum requirements in rule 18. Therefore, if any new height-limited boundary points are created on a non-primary parcel boundary, either new or existing, the reduced levels must be in terms of NZVD2016, except as allowed by rule 62.
Rule 62(1) requires reduced levels in a new unit plan of an existing unit title development to be expressed in terms of the datum used for the previously deposited CSD for the unit title development. This may be an unofficial datum.
Rules 60 and 75 may be interpreted to allow the reduced levels of an existing height-limited non-primary parcel boundary and its associated points, that are adopted or accepted as part of a new non-primary parcel, to remain in terms of the datum of the source CSD they are adopted from. However, all reduced levels must be in terms of a single datum and the CSD must not create any new height-limited boundary points.
There is no exemption under the CSR 2021 that allows the reduced levels of an existing height-limited primary parcel boundary and its associated points to remain in terms of the datum of the source CSD they are adopted from. They must be in terms of NZVD2016 unless dispensation is granted because the requirement is impractical or unreasonable.
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Permanent reference marks and vertical control marks for height-limited boundaries
Boundary points for height-limited boundaries which are mathematically described under rule 12(2)(a) must be referenced to permanent reference marks and related to vertical control marks as follows.
Permanent Reference Marks (PRMs)
Referencing height-limited boundary points to PRMs allows the position of height-limited boundary points to be re-established within allowable accuracy tolerances in the future.
There are different referencing requirements for boundary points on primary parcels, unit parcels and other non-primary parcels.
A new height-limited boundary point defined by a reduced level on a primary parcel must be referenced by a PRM (r 31(c)). The survey must include at least three PRMs (r 32(2)), and two of them must have a reduced level (r 34).
A new height-limited boundary point on a unit parcel must be referenced to a PRM (r61(1)). The survey must include at least two PRMs with reduced levels (r 61(5)).
A new height-limited boundary point is not required to be referenced to a PRM if it:
- is on an easement, lease or covenant parcel, or
- coincides with an accepted boundary.
All height-limited boundary points required to be referenced, whether on a primary or non-primary parcel, must meet the applicable vertical accuracy standards in rule 21. They must also be within the applicable distance of a PRM for the class of the boundary point (r 32(1) and r 61(4)).
Each PRM must be within the applicable distance for the boundary class of at least one of the boundary points required to be referenced (r 32(2) and r 61(5)).
A survey diagram must include the reduced level of a reference mark that is required by rules 34 and rule 61(5) to have a reduced level (r 82(d)).
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Vertical Control Marks (VCMs)
If a height-limited boundary and its associated boundary points are defined by a reduced level, a VCM must be included in the CSD (r 18(2) and r 18(3)). Inclusion of a VCM ensures that the height-limited boundary points are accurately spatially positioned in terms of the official vertical datum.
If an unofficial datum was used in a previously deposited CSD for the unit title development, a VCM included in the survey to meet the requirements of rule 18 must have a reduced level in terms of the unit title development (r 62(2)).
VCMs are existing survey marks which have been assigned a height in terms of NZVD2016 with a Landonline order of 3V or better (Schedules 2, 5 and 6). They can be searched for in Landonline Web Search or the LINZ Geodetic Database by selecting the NZVD2016 and 1V-3V layers. A VCM in terms of an old local vertical datum, even if converted to NZVD2016, is not acceptable.
All height limited boundary points required to connect to a VCM, whether on a primary or non-primary parcel, must meet the applicable vertical accuracy standard in rule 20(2).
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Description of a height-limited boundary as the surface or bed of a water body
The surface or bed of a water body may be used as a height-limited boundary under rule 12(2)(b). In this case, no boundary points are required to have a reduced level, and the boundary does not need to be referenced to a PRM or a VCM included in the survey. However, the location of the boundary must be clearly described in a CSD. Inclusion of a cross-section as a plan graphic is a convenient way to achieve this.
Where the surface or bed of a water body has been used as a height-limited boundary, the horizontal extent of the height-limited boundary may coincide with a water boundary. If so, the survey diagram must describe the physical feature used to define the boundary (r 88).
Examples include:
- 'Top of bank'
- 'Line of vegetation'
The title diagram must describe the legal position of the boundary (r 104). Examples include:
- ‘Bed of river/lake’
- ‘Annual fullest flow’, for the surface of a river
- ‘Annual highest level’, for the surface of an uncontrolled lake.
Note that the physical description and the legal description of the boundary may be different, depending on the circumstances.
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Accounting for all land in an existing primary parcel
If a new primary parcel has a height-limited boundary, all of the three-dimensional space occupied by the existing primary parcel(s) being extinguished must be included in one or more new primary parcels, residue parcels or balance parcels (r 39(3)).
Parcel appellations
Where a parcel is limited in its vertical extent by a height-limited boundary, the parcel appellation must have a 'Height-Limited' prefix (r 43, Table 3). This is achieved by selecting the ‘Height-Limited’ option in the Parcel Details screen in Landonline.
Add and edit a new parcel (Landonline survey support)
The full appellation should be included in the dataset description (r 71(c)(i)). For example, “Lots 1-3 and Height-limited Lots 4 and 5 being a subdivision of…”
The appellation can be abbreviated (e.g. H-L Lot 1) on plan graphics, as long as it is unique. The appellation or its abbreviation should be used consistently throughout the CSD, including supporting documents, where possible.
Parcel areas
Where a parcel shape changes at different elevations, the area of the parcel must be calculated from the widest extent of the parcel when vertically projected onto a horizontal plane, for example, the vertical shadow or bird's-eye view from directly above (r 41(4)). This principle applies in all cases, including parcels that are in airspace or underground, or are made up of various floors of different heights, such as height-limited parcels (see Figure 2).
The area of a parcel must be correctly calculated from boundary information defining the boundaries (r 41(5)(a)) and be expressed in hectares (r 41(5)(b)).
Note that there is no requirement to calculate the sum of areas for all primary parcels depicted in a Cadastral Survey dataset (CSD). The sum of height-limited parcel areas will generally exceed the area of the extinguished parcel due to overlaps. A C660 warning is likely to appear in the pre-validation report that will need to be explained in the survey report.
Figure 2: Area of parcel
Ground movement
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CSD requirements for height-limited boundaries
Record of survey requirements
The vertical datum must be selected in the Survey Header to ensure compliance with rule 77.
A record of survey must include the accuracy class of a height-limited boundary that is mathematically described (r 79). Where the boundary class cannot be captured in the vector panel, the accuracy class can be included on the plan graphic that depicts the boundary. However, if all the boundaries in a CSD are the same as the accuracy class captured in the survey header, it is not necessary to include the accuracy class on the plan graphic.
A VCM must be included in any survey that defines height-limited boundary points by reduced levels (r 18(2) & (3)). The VCM does not have to be captured, but its details must be included in the CSD (r 82(b) & (e)). Where the VCM is not captured, an annotation must be added to the title diagram that includes:
- “Reduced levels are in terms of”
- the mark name of the VCM and its geodetic code
- the reduced level of the VCM
- the applicable vertical datum.
Survey diagram requirements
A survey diagram must depict:
- the horizontal and vertical extents of any height-limited parcels included in the CSD (r 83(a))
- the relationship between a height-limited parcel and its boundaries and boundary points in the horizontal and vertical extent (r 83(d))
- the spatial relationship between all primary parcel boundaries on the survey, including the boundaries of height-limited parcels (r 83(e)(i)).
For a height-limited boundary that is mathematically described, the survey diagram must also show enough information to enable the relationship between any position on the height-limited boundary surface and any other boundaries to be accurately ascertained (r 86).
To meet referencing requirements for height-limited boundaries, a survey diagram must also include:
- the reduced level for each of the two PRMs required by rules 34 and 61(5) to have reduced levels (r 82(d))
- the reduced level of a vertical control mark required to be included in the survey by rule 18 in terms of NZVD2016, or by rule 62(2) in terms of an unofficial datum (r 82(e)).
A height-limited boundary and related reduced levels must be shown on a survey diagram in a clear and unambiguous manner (r 91(a)). For example, reduced levels must not conflict with declinations or elevations or, in the case of unit developments, be confused with permanent structure boundaries.
Title diagram requirements
A title diagram must depict the horizontal and vertical extents of any height-limited parcels included in the CSD (r 97(1)(a)).
The horizontal extent of a height-limited parcel must be depicted on a title diagram in its entirety on at least one sheet drawn to scale with its boundaries (r 97(3)(a)).
A title diagram must depict a height-limited boundary at a scale that clearly shows the shape and location of the boundary, including vertically, in relation to other boundaries of the parcel (r 102). This may be achieved by a plan graphic included in the CSD.
All information presented on a title diagram and associated plan graphics must be clear and unambiguous (r 107(a)). Where a plan graphic shows a right-line boundary at a different height, the bearing and distance should also be shown (r 105(1)).
Reporting requirements
The survey report must include details about the basis for determining the origin of levels (r 72(e)). The report should describe how the reduced levels were established and confirmed. The reduced level must be in terms of the latest NZVD 2016 published value for that mark. An origin mark may be subject to vertical disturbance and needs to be assessed separately to its horizonal reliability. If an alternative mark was used to check reliability, this should be detailed.
A description is also required in the reporting on the methods and equipment used when establishing and transferring levels to ensure compliance with the accuracy standards (r 72(o)).
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Field information
Field information must be included in the CSD where the record of survey includes reduced levels that required vertical observations.
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Height-limited easements
The title diagram must depict the horizontal extent and, if applicable, the vertical extent of the parcel (r 97(1)(a)). The schedule/memorandum does not form part of the title diagram which means only including a reduced level in a schedule does not satisfy rule 97(1)(a). Upper and lower limits can still be shown in the schedule, however a vertical step is not considered to be an upper or lower limit and should therefore not be included in the schedule.
Figure 3: Vertical step
Care should be taken to ensure any height limitations assigned to ‘rights and powers’ are within or equal to the height limits which currently constrain the individual parcels. For example, if the intention is to create rights of way and light and air rights, where the right of way has height limits between reduced levels 3.60m and 7.20m and the light and air easement has height limits between 7.20m and 13.20m, two separate parcels should be captured. This example is shown in figure 4 where HL Areas B and C have been created.
Figure 4: A vertical elevation showing the two examples mentioned above.
Height restrictive covenants
A covenant parcel to be subject to a height restriction is required to be depicted as a non-primary parcel. The parcel must be defined horizontally, but the surveyor can decide if the parcel is defined vertically – in other words, the parcel may, but does not need to, have a height-limited boundary.
If the covenant parcel is defined vertically by a height-limited boundary, the CSD must comply with the rules relating to reference marks and vertical control marks for height-limited boundaries, and with all CSD requirements for height-limited boundaries.
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- Permanent reference marks and vertical control marks for height-limited boundaries
- CSD requirements for height-limited boundaries
If the parcel is not defined vertically by a height-limited boundary, it is presumed that the height restriction will be defined in the registrable instrument creating the restriction. In this case, the height restriction will be defined in a manner determined by the parties to the instrument.
Where it is intended that a registrable instrument will define the height, the CSD may include information about the height of the restriction as supporting information (for example, reduced levels for survey marks, datum information, or the survey report expressing an intention to restrict a right). In this case, the survey diagram, title diagram and supporting information must not depict a height-limited boundary or show annotations that seek to describe the height restriction.
Where an existing height-limited boundary for a covenant is adopted, it must be adopted from the source CSD as defined in rule 75(2)(a). It is not necessary to include information from the source CSD that defines the extent of the boundary, which may include a height origin, level and source, bench marks, heights and heighted boundary marks. However, the source CSD for the height-limited boundary should be clearly identified, so that the information can be easily located by future surveyors.
Spatial capture requirements
When defining parcels restricted in height such as a tunnel or the subdivision of a multi storey building, the horizontal and vertical extent of each parcel must be depicted on the survey and title diagrams (r 83(a), (d), (e)(i) and r 97(1)(a)). All parcels must be captured in Landonline as required by the Standard for lodgement of cadastral survey datasets (Lodgement standard).
Primary parcels
Landonline does not permit parcels with the same parcel layer to overlap; therefore, primary parcels must be captured separately in either the ‘Primary’ or ‘Strata’ or ‘No Topology’ layer as follows. Some parcels will require boundary vector capture while others won’t.
Parcel(s) substantially at ground level (touching the parcel at ground level or with a similar reduced level) must be captured with a ‘Primary’ parcel layer. Parcels either immediately vertically above or below the parcel at ground level must be captured with a ‘Strata’ parcel layer (Lodgement standard 4.4(c)), unless an exemption from the Standard is granted. These parcels are referred to as strata parcels in Landonline. More than one parcel can be created with a ‘Strata’ layer, providing they don’t overlap horizontally.
If there is another height-limited primary parcel anywhere vertically above or below the strata parcel, it must be captured as an aspatial parcel and defined on a plan graphic (Lodgement standard 4.4(c)).
Illustration of parcels in relation to ground level
The below figure illustrates parcels in relation to ground level.
To comply with Lodgement Standard 4.4(c)(ii), the surveyor may choose either the below set of Height-limited Lots 4 and 5 or the above set of Height-limited Lots 9 and 10 (but not both sets) to be in the ‘Strata’ parcel layer and with vector capture. The set of lots not chosen to be in the ‘Strata’ parcel layer will then be either lots above or below a strata parcel hence they must be captured as aspatial parcels and depicted in a plan graphic.
Figure 5: Vertical view of HL Lots 1 to 12 to illustrate parcels in relation to ground level
If the option to capture the parcels immediately above the designated ground level parcels is chosen, an example of how the above CSD could be captured is:
- H-L Lots 1, 2 and 3 are captured spatially in the primary topology layer
- H-L Lots 9 and 10 are captured in the strata topology layer
Note, because a ground level footprint of H-L Lot 1 has already been captured spatially in the primary layer, the upper level ‘footprint’, including a bearing and distance for every right-line boundary, is depicted on a plan graphic.
- Lots 11 and 12 are captured as aspatial parcels and depicted on Plan Graphics
- HL Lots 4 to 8 are captured as aspatial parcels and depicted on Plan Graphics
Non-primary parcels
Non-primary parcels must be captured separately in either the ‘Secondary’ or ‘Tertiary’ layer as follows. The non-overlapping height limited non-primary parcels substantially at ground level must be captured with a ‘Secondary’ parcel layer. Parcels immediately vertically above or below the parcel at ground level (touching the parcel at ground level or sharing the same reduced level) must be captured with a ‘Tertiary’ parcel class. More than one parcel can be created with a ‘Tertiary’ layer, providing they don’t overlap horizontally.
If there is another height-limited non-primary parcel vertically above or below the tertiary parcel, it must be captured as an aspatial parcel and defined on a plan graphic (Standard for lodgement of cadastral survey datasets section 4.5(b)).
Note that unit title, company lease or cross lease parcels do not need to be spatially captured (Standard for lodgement of cadastral survey datasets section 4.2.2(a)).
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