By Anthony Whealy, Partner, Ben Salon, Associate, and James Oldknow, Associate
Most land in NSW (but not all) is typically subject to a ‘height of buildings’ (‘HOB’) development control which is designed to limit the height of development that may occur. This, together with ‘floor space ratio’ development controls, are at the very heart of the NSW planning system, as these two controls largely set the outer limits of the bulk, scale and therefore yield of development that is achievable on any development site. You can read all about calculating Gross Floor Area (for Floor Space Ratio purposes) in our previous article.
The HOB control in the Standard Instrument Local Environmental Plan (found in clause 4.3) is the form this control most commonly takes, at least via most council local environmental plans (some State environmental planning policies have different definitions), and this states that:
“4.3(2) The height of a building on any land is not to exceed the maximum height shown for the land on the Height of Buildings Map.”
In order to understand the meaning of the first few words of that control, the Standard Instrument offers a definition of “building height (or height of a building”) which states as follows:
“building height (or height of building) means—
(a) in relation to the height of a building in metres—the vertical distance from ground level (existing) to the highest point of the building, or
(b) in relation to the RL of a building—the vertical distance from the Australian Height Datum to the highest point of the building,
including plant and lift overruns, but excluding communication devices, antennae, satellite dishes, masts, flagpoles, chimneys, flues and the like”.
Under this definition, it is essential to know how to correctly understand and identify the “ground level (existing)” of any development site for the purposes of maximising the development that may be undertaken. It is the term “ground level (existing)” which in our experience causes so much confusion and debate in the context of development applications in NSW.
Accordingly, of relevance is the definition of “ground level (existing)” in the Standard Instrument which states:
“ground level (existing) means the existing level of a site at any point.”
This should be contrasted with earlier definitions under NSW planning laws which historically and typically had referred to “natural ground level” – a far simpler term to understand and identify, usually achieved just by observing and averaging the natural fall of a site in comparison to other surrounding land parcels, and ignoring any man-made changes or improvements to those land parcels or to the site itself.
Perhaps unsurprisingly to our readers, calculating the “ground level (existing)” can be complex. Nominating the “ground level (existing)” is usually achieved by taking the lowest level directly and vertically beneath the highest part of the proposed development on a site (based on surveyed RLs), to determine a maximum building height dimension. However, where an existing building occupies the whole of the site area so that there is no longer any ‘ground’ (as in soil/garden/paving) around the building, from which the existing ground level could be determined, this task is not so straight forward. The issue is compounded where ‘below ground’ excavation has previously occurred on the site (for example below ground basements) and even more so where excavations have occurred only in parts or pockets of a site. In such a situation, if the lowest point of the existing development (i.e. the floor of the lowest basement) is taken to be ground level (existing) then development potential may be artificially and considerably limited, and there may also be wildly differing ‘existing levels’ on that land at multiple points. Similarly, issues arise whenever there is some form of concrete slab on a site – is the top of the slab the ‘ground level (existing)’, or is that to be measured from below the thickness of the slab?
In our experience, these issues are being litigated extensively in the Land and Environment Court, and of course are subject to even more frequent debate when council staff assess DAs all throughout NSW on a daily basis.
We are constantly being asked to review DA plans and drawings and provide advice to developers, architects, and town planners alike, or to write opinions suitable to be presented to councils and various planning panels, as to where a particular ground level should be measured from, and therefore whether any consequential height breaches arise. It may also come as no surprise that we are often asked to litigate disputes in the Land and Environment Court (the ‘Court’) on what is the correct calculation of “ground level (existing)”. In our experience, what is found to be “ground level (existing)” is also highly relevant in development applications where (always contentious) view loss issues arise.
In this article we concisely bring together the Court’s current answers to the most common (and yet vexed) questions and decisions on calculating “ground level (existing)” with respect to HOB controls.
Land that has been Completely Built Out, Excavated and/or is Sloping Land
Bettar v Council of the City of Sydney  NSWLEC 1070
The original and therefore leading decision on determining “ground level (existing)” on land that is sloping or completely excavated is the decision of Commissioner O’Neill in Bettar v Council of the City of Sydney  NSWLEC 1070 (‘Bettar’). In Bettar, consent was sought for, amongst other things, a four and five storey residential flat building on a site where an existing building already occupied the entire site, meaning there was no longer any “ground” for determining the existing ground level. In addition, there was an existing part-basement excavated into one part of the site.
The Council’s argument focused entirely on the existing building on the site and took the approach that the “ground level (existing)” should be calculated using the ground floor level of the existing building, and then dropping it down to the basement level in the part of the site where the existing basement was located.
The Commissioner determined that once the existing building is demolished, the ground levels of that prior building would no longer be discernible or relevant as a starting point for measuring the height of any new building, and that it would be conceivable that surrounding properties (with differing ground floor levels) could have starkly different height limits arising from the same development standard. The Commissioner held at paragraph  that this would result ‘in an absurd height plane with a large and distinct full storey dip in it as it moves across the site and crosses the basement of the existing building, which relates only to a building that is to be demolished and has no relationship to the context of the site.’
The Commissioner preferred the approach of the Applicant on this issue which was for the existing ground level of the site to be determined by extrapolating the ground levels found on the footpath (i.e. – outside the site) across the entire site to measure the vertical distance to the highest point of the building. The Commissioner’s reasoning for this, given at paragraph , was that the ‘level of the footpath at the boundary bears a relationship to the context and the overall topography that includes the site, and remains relevant once the existing building is demolished.’ In our experience, this has become known as the extrapolation method for determining “ground level (existing)”.
We consider that this is a practical approach to measuring height, albeit that it tends to be very reminiscent of the old ‘natural ground level’ approach to measuring height. In other words, it takes a non-literal approach, but rather a pragmatic and workable approach, to determining ‘ground level (existing)’.
Stamford Property Services Pty Ltd v City of Sydney  NSWLEC 1189
Similar circumstances came before the Court once again in Stamford Property Services Pty Ltd v City of Sydney  NSWLEC 1189 (‘Stamford’) although this time on a much larger and more steeply sloping site than in Bettar. Consent was sought for, amongst other things, the partial retention of existing development on the site and the construction of a 19 storey tower building with basement parking on a Sydney CBD site. The context of the site was once again of paramount concern to Commissioner Pearson and Acting Commissioner Smithson, who found at paragraph  that ‘the extent of excavation from site to site could lead to different height limits applying to adjoining buildings on redevelopment of any of those sites.’
Unlike the site in Bettar, which had two street frontages and vacant adjoining land from which levels could be measured, here, the highly developed surrounds meant there were limited levels from which to even extrapolate a ground level (existing). Nevertheless, the Court noted that the availability of survey information necessary in order to be able to apply the Bettar extrapolation method may vary from site to site, but was still possible even with limited information, and that there was sufficient actual and surveyed levels from the public domain in this case to arrive at a ‘ground level (existing)’ figure for the (excavated) centre of the site, being an average between two surveyed points, rather than a surveyed (and excavated) ground level.
Of interesting note from the decision in Stamford is the statement at paragraph  by the Commissioners that the Bettar extrapolation method:
“provides a practical operation to the definition, both for a greenfield site and, as here, a modified site in a built environment. It places the proposed building in its context, rather than relying on the present built form of any existing development on a site.”
This highlights that the Bettar extrapolation method may be applicable, even in the case of a greenfield site, where actual surveyed ground levels result in absurd or irregular height planes that do not place a proposed building in the proper context of its site and surrounds. There is more on this below.
Tony Legge v Council of the City of Sydney  NSWLEC 1424
Solidifying the application of the decisions in Bettar and Stamford to sites that are wholly built out, in Tony Legge v Council of the City of Sydney  NSWLEC 1424 (‘Tony Legge’) the Commissioner found at paragraph  that ‘it is appropriate to take the levels of the site at its interface with the public domain.’ Further and importantly, the decision in Tony Legge reinforces the importance of “placing ‘the proposed building in its context, rather than relying on the present built form of any existing development on a site’.” [our emphasis added].
Once again, readers will notice that the Court decisions are gently pushing the interpretation of ‘ground level (existing)’ back towards something more sensibly akin to ‘natural ground level’.
Land that has not been Completely Built Out or Excavated
The decisions detailed above considered land that was wholly built out and/or had been previously excavated for existing developments. The following examples will highlight the approach of the Court where land on which development is proposed is not completely built out or excavated.
Strebora Pty Ltd v Randwick City Council (No. 2)  NSWLEC 1575
In Strebora Pty Ltd v Randwick City Council (No. 2)  NSWLEC 1575 (‘Strebora’), development consent for a four-storey residential flat development over basement car parking was being sought on a site where a residential dwelling that had been well set back from all boundaries had already been demolished. Despite the apparent availability of existing ground areas on parts of the site, the Applicant argued that the ‘ground level (existing)’ should be determined with reference to levels at the street.
In this case the Court found the Bettar extrapolation method was not directly applicable for reasons including that the (now demolished) dwelling had not occupied the entire site (meaning there were patches of existing ground on which levels could be taken – although largely not detailed on the survey that accompanied the DA) and that the fall across the land meant it was not sufficient to determine the maximum allowable height of the building from existing ground levels at the boundary with the street.
Once again and despite Bettar not being directly applicable, the principle that the determination of ‘ground level (existing)’ must bear some relationship to the overall topography and context of the site is central to decision in Strebora.
Gejo Pty Ltd v Canterbury-Bankstown Council  NSWLEC 1712
The decision of Commissioner Gray in Gejo Pty Ltd v Canterbury-Bankstown Council  NSWLEC 1712 (‘Gejo’) serves to remind us that the extrapolation method used in Bettar and Stamford, although at times necessary and practical, is not intended and cannot be used to overrule the definitions and controls contained in the relevant local environmental plans.
As was the case in Strebora, the sites the subject of the decision in Gejo contained single residential dwellings. The proposal at hand was for the demolition of these dwellings and construction of two 6-storey mixed-use buildings over two levels of basement carparking. In Gejo the Commissioner noted at paragraph  the comments from Stamford that the ‘actual height of the proposed building must first be determined by application of the [relevant] LEP definitions and that the extrapolation approach used in Bettar and Stamford was justified in circumstances where the existing ground level is not known due to extensive development on the site’.
On the other hand, given the sites in Gejo had not been extensively excavated and the ground level was known and able to be surveyed, the Commissioner held that the usual method of taking the lowest level on an existing site, as shown on the site survey, directly and vertically beneath the highest part of the proposed development reflects the definitions in the LEP and was therefore to be used to calculate the building height.
It is important to note the finding of the Commissioner at paragraph  that ‘[t]he fact that there is an uncharacteristic depression on the site is not relevant to this calculation [of ground level (existing)], but might be relevant to the request to vary the height control considered below’ (in other words, this may be relevant to a clause 4.6 variation request where the topography or excavation within a site results in a consequential height of buildings breach). From this we can see that the comments in Stamford that the extrapolation method may be applicable to ‘green field’ sites is not a cart-blanche way to avoid the HOB definitions and controls contained in the relevant local environmental plans – clearly, something more is required with respect to placing the proposed building in its context on the site and surrounds.
Nicola v Waverley Council  NSWLEC 1599
The recent decision in Nicola v Waverley Council  NSWLEC 1599 (‘Nicola’) (a matter where we represented the applicant) is an example of where the Bettar extrapolation method can applied to levels contained within the site the subject of the development application. In Nicola, an existing slab made the determination of the “ground level (existing)” (which was arguably hidden underneath the slab) a difficult task. Despite the Council arguing that the use of the extrapolation method was not appropriate as the site had not been completely built out (as in Bettar and Stamford), the Commissioner held at paragraph  that the extrapolation method should be applied and that in this case, that approach is:
“not inconsistent with the principle applied in Bettar and Stamford Properties, which by necessity had to rely on the footpath levels outside the property boundaries because the buildings, in those cases, occupied the whole of their respective sites. In the subject development proposal the known ground levels identified are also outside the building and also closest to its exterior walls. The fact they are located within the site’s property boundaries, as opposed to outside the boundaries and on the footpath, does not derogate from the key selection criteria of closest immediate proximity.”
From this decision that we can see that where the facts and circumstances of the case make the use of the extrapolation method appropriate, the levels to be used should be taken from the closest immediate proximity where existing ground can be found, whether that be inside or outside of the subject site.
The subject of the decision in Alexakis Building Pty Ltd v Waverley Council  NSWLEC 1129 was an application to modify an existing consent to add, amongst other things, a roof top terrace atop a 3 storey dwelling.
On the issue of determining ‘ground level (existing)’ the Court did not accept, at paragraph , the agreed position of the parties’ experts “that the height of the proposal is to be determined either by taking existing ground level as the excavated level of the site as it is now or the excavated level of the site under the garage of the recently demolished dwelling on the site…”. Instead, the Commissioner found that as the subject of the appeal was a modification application to a development consent, “it is appropriate to consider the existing ground levels on the site survey submitted as part of the [original] development application package.”
Here it can be seen that there is a material difference between a fresh development application and an application to modify an existing consent.
Slab thickness – should it be excluded?
We have observed a growing trend of councils arguing that where the ground of a site has an existing concrete slab, that the height measurement should be artificially lowered by say 200mm below that top of that slab, to where the ground beneath the slab might reasonably be expected to be found. Unfortunately, we have not yet seen a decision of the Court ruling on this issue, potentially because the argument is not ultimately pushed by consent authorities when those appeals reach their final hearing.
For the time being, we would caution that in our opinion, that approach (deducting the thickness of an existing slab on a site, to say that a proposed building is say 200mm taller than the applicant has suggested) is legally wrong. The measurement of height is to be taken from the ground level that is ‘existing’. That word cannot be ignored. The definition does not refer to the ground level that was ‘pre-existing’ before a finished ground level was constructed.
Further, and put simply, a finished (concrete) ground level is nevertheless a ‘ground level’, which may be walked upon and represents the ground of the site. Whereas to instead try to estimate where one might find the underlying soils below that finished ground level is entirely contrary to the concept of ground level ‘existing’ and would more correctly be described as a ground level ‘pre-existing’, or ‘natural ground level’. It also ignores the practical reality that most soils would be compacted before a slab is poured, therefore artificially lowering that underlying ground level in any case. We see no reason to justify the lowering of the height measurement down to some pre-existing, but further compacted, underlying soil level. The definition simply does not allow for this extent of manipulation of the measurement of building height.
As always though, watch this space. We will update our readers if there are any further developments on this interesting issue.
Key Take Aways:
The follow key points can be taken away from the above decisions and principles with respect to calculating ground level (existing):
- The context of a development site is of paramount importance and highly relevant where existing topography (natural or developed) would result in an absurd or at least irregular height plane, and it is a result that would not place a proposed building in its true context on the site and surrounds. That scenario will often open the door to using the extrapolation method for determining ground level (existing).
- In cases where a site has been completely built out and/or excavated, existing ground levels might be obtained from outside the site, albeit close to the boundary and at the interfaces with the public domain. Even limited extrinsic levels may be sufficient for using the extrapolation method in certain and appropriate circumstances. There may also be facts and circumstances (for example the construction of existing development on the site such as that which was seen in Nicola) that warrant the application of the extrapolation method using levels from within the site.
- Modification applications will likely see ground level (existing) from the original development consent applied, and that should be given proper consideration where there are options for proposing future development.
- It should not be forgotten that clause 4.6 requests can be used to vary HOB development controls (subject to justification) and that may be a more appropriate approach (i.e. where there is uncharacteristic topography such as that which was seen in Gejo) to maximising development yield.
- It should also be noted that HOB may also appear in the relevant instruments providing for specified height restrictions to be varied or modified in certain circumstances, for example, to prevent overshadowing of public open space, for air safety reasons or for the purposes of promoting design excellence.
Need further assistance?
If you need further assistance to determine the ‘ground level (existing)’ at your proposed development, or to provide a legal opinion suitable to be submitted as part of a development application package, then we are available to assist. Of course, we also specialise in development application appeals should any dispute arise with Council on this topic needing resolution in the Court.