Read requirements for depiction of units on unit plans.
The Rules for Cadastral Survey 2010 require the boundaries of units to be clearly and unambiguously defined on the Diagram of Survey (see rules 9.6.4 and 9.6.9 in particular where the provisions for permanent structure boundaries are used).
Requirements include the need to depict the structure and its relationship to the unit boundary. Depiction needs to be primarily diagrammatic but can be supported by words.
The diagram must clearly depict the shape of each unit so that someone without survey expertise can readily and correctly locate the legal boundary in relation to the physical structures. The diagram does not have to include every nook and cranny.
The Interpretation Guide provides some guidance on this, particularly where the boundary is not coincident with a physical structure.
Boundary coincident with physical structure
Where the boundary is coincident with a physical structure the Diagram must make the relationship between the boundary and the structure very clear. This relationship can be depicted or it can be annotated – provided it is clear. See some examples in Figures 1 and 2.
The annotation can be applied to individual boundaries or it could be a generic note, provided that the relationship is clear in every instance of the boundary. For an example see Figure 3.
The physical structure does not have to be depicted around the full extent of every unit where the boundary and the relationship to the structure are the same for each unit. Generic diagrams may be used, and may be distorted to provide clarity, provided they are referred to on the main diagram.
Requirements also apply to vertical boundaries
The above approaches can be applied for both horizontal and vertical boundaries, which are treated the same in the rules relating to permanent structure boundaries. See example in Figure 4.
Boundary coincident with underlying primary parcel boundary
Where the unit boundary coincides with the underlying primary parcel boundary, the relationship of the physical structure to the boundary must be clearly depicted, particularly where the structure extends beyond the boundary – see example in Figure 5. Generic diagrams may be used and may be distorted to provide clarity, provided they are referred to on the main diagram.
A boundary segment that connects from one that is coincident with the physical structure to one that is not (including one that is coincident with the underlying parcel boundary) must be clearly defined in relation to each. For instance, that boundary might follow the extension of the centreline of the wall to where it meets the external boundary. See examples in Figures 6 and 7.
Vertical boundary not coincident with permanent structure
Some unit boundaries may be located in space above (or below) the physical structure. Such boundaries can be defined by dimensions (usually vertical distances) from clearly defined points on the structure (see rule 6.9(b)). The 20m limit (rule 6.9(b)(ii)) only applies horizontally. See Figure 8 for an example.
If reduced levels are used to define these boundaries, the boundary is not being defined in relation to the physical structure and the Stratum Boundary requirements apply, including the witnessing and PRM requirements.
Use of previous boundaries defined by reduced levels
In specified circumstances, the boundaries of units defined on a CSD approved under previous rules are allowed to be depicted in the same manner on a new CSD. Refer to Rule 19 in the Rules for Cadastral Survey 2010.
Such a boundary may sometimes be common with a new unit parcel. An example would be where a unit being retained has an upper limit defined by a reduced level, which is common with the lower limit of a unit being redeveloped. These boundaries may continue to be defined by those reduced levels in the new CSD. Such boundaries are not considered to include ‘new stratum boundary points’ (see rule 7.3.1(d)) and therefore witnessing and PRMs for those points are not required in the CSD.