Australia: Determining minimum unit sizes in the residential flat design code


The Land and Environment Court (Court) has handed down judgment on minimum unit sizes required by State Environmental Planning Policy No 65 (Design Quality of Residential Flat Development) (SEPP 65) and the Residential Flat Design Code (Code).

While the Code's minimum unit sizes have previously been considered outside of SEPP 65, the Court in Botany Bay City Council v Botany Development Pty Ltd (No 2) [2015] NSWLEC 55 held that, under SEPP 65, minimum unit sizes were not those set out in the Rules of Thumb contained in the Code. Rather, they are set out in the Code's table in Part 3, which specifies the internal and external areas for nine different apartment "types".

The practical effect of this decision is that, where SEPP 65 is applicable, the larger minimum unit sizes in the table (both internal and external) must be utilised. The smaller minimum unit sizes in the Rule of Thumb (1 bedroom: 50m2; 2 bedroom: 70m2; 3 bedroom: 95m2) are not relevant.


The respondent, Botany Development Pty Ltd (Botany Development), made a development application for the demolition of improvements on land, the construction of a 3 – 6 storey residential development containing 158 units, and associated works (Proposed Development).

Development consent for the Proposed Development was granted by Brown C of the Land and Environment Court (Court). In granting consent, the Commissioner determined that:

  1. the apartment sizes in the Proposed Development met the recommended internal and external areas in the Residential Flat Design Code (Code);
  2. therefore, by virtue of clause 30A(1)(b) of State Environmental Planning Policy No 65 (Design Quality of Residential Flat Development) (SEPP 65), consent to the Proposed Development could not be refused on the basis of unit size;
  3. therefore, the minimum unit sizes contained in clause 4C.5.1 of the(DCP) could not be a reason for refusing consent; and
    The City of Botany Bay Development Control Plan 2013
  4. in any case, the effect of clause 6 of SEPP 65 was that the minimum unit sizes in SEPP 65 prevailed to the extent of any inconsistency with the DCP relating to minimum unit size.

The appellant, Botany Bay City Council (Council), brought an appeal under section 56A of the Land and Environment Court Act 1979, heard by Sheahan J, claiming that Brown C erred in law by determining that "unit size" should not be a reason for refusing consent to the Proposed Development.

Fundamental to the appeal was the consideration of what were the minimum unit sizes in the Code for the purpose of SEPP 65 and whether the Proposed Development met those sizes.

The parties' competing claims concerning minimum unit sizes were both informed by the contents of Part 3 of the Code and, specifically, the contents under the heading "Building Configuration (Apartment Layout)". Council claimed that the minimum unit sizes were contained in a table within that section, which set out the internal and external areas for nine different types of apartments (MUS Table). The MUS Table is reproduced at the end of this article.

Botany Development, on the other hand, claimed that the minimum unit sizes were those set out in the "Rule of Thumb" within that section (MUS Rule of Thumb), being:

  • 1 bedroom apartment 50m2;
  • 2 bedroom apartment 70m2; and
  • 3 bedroom apartment 95m2.

All of the apartments in the Proposed Development exceeded the sizes set out in the MUS Rule of Thumb. However, only 63% of the apartments exceeded the sizes set out in the MUS Table.


The Court was directed to two prior decisions involving minimum unit sizes under the Code:

  1. Botany Bay City Council v Marana Developments Pty Ltd [2012] NSWLEC 15 (Marana Case); and
  2. Botany Bay City Council v Minister for Planning and Infrastructure [2015] NSWLEC 12 (MPI Case).

Although the Marana Case concerned minimum unit sizes under SEPP 65, the development at issue in that case met the standards in both the MUS Table and the MUS Rule of Thumb. Sheahan J noted that as the decision in the Marana Case proceeded on the basis that the minimum areas were found in both the MUS Table and the MUS Rule of Thumb, the decision was not determinative of the issue currently subject to appeal.

The MPI Case concerned an application for approval of a residential development under Part 3A of the Environmental Planning and Assessment Act 1979. In determining the application, the Planning Assessment Commission imposed a condition on the approval requiring all unit sizes to "meet the requirements of the [Code]".

On appeal to the Court in the MPI Case, the parties disputed whether the minimum unit sizes in the Code were those contained in the MUS Table or the MUS Rule of Thumb. Unlike the proceedings before Sheahan J, this issue in the MPI Case was only considered in the context of the requirements of an approval. The minimum unit sizes in that case could, therefore, be determined without reference to SEPP 65.

On this basis, the Court in the MPI Case held that the minimum unit sizes in the Code were to be determined only by reference to the wording of the Code. Sheahan quoted the relevant part of the judgment in the MPI Case as follows [at 144-145]:

144 It was unfortunate that the condition ... used the phrase "requirements of the [Code]". As noted the [Code] does not of itself have the force of law. Moreover the language of the entire document is anything but prescriptive. Thus the [Code] refers to the table in [129] and the apartment designs as merely "provid[ing] information" and as being only "examples" for use as a "comparative tool". They are said to be useful for "recognising well-organised, functional and high quality apartment layouts". It does not purport to suggest that the apartment types are mandatory or that the apartment areas listed represent some minimum standard. This is only reinforced by the introductory section of the [Code] noted in [127] which describes the "directive text", being the area that includes the table noted in [129], as only "outlin[ing] better design practice guidelines and provide[ing] some possible design solutions for achieving the guidelines." The areas listed in the table noted in [129] simply cannot be described as "[u]nit size requirements".
145 In general parlance "rules of thumb" do not constitute "requirements". Instead they are guidelines that lack exactitude. Further the apartment areas listed in the last dot point in [131] are described as able to be used "as a guide" and the areas are 'suggest[ed]" to be used. However they are far more easily characterised as "requirements" than the table noted in [129]. They are at least described as being "rules" (albeit "rules of thumb") and are referred to as "minimum apartment sizes" (albeit to be used "as a guide"). Further the rules use more exhortatory language than the descriptive text in that they advise what "should be" done, as opposed to merely "provid[ing] information" and listing "examples" for use as a "comparative tool". To some extent the description of the "rules of thumb" in [127] support this in that they reiterate their role in recommending "minimum standards" albeit as a "guide for local decision making."

[emphasis added]

While this reasoning supported the submissions of Botany Development, Sheahan J determined that it was not relevant to the present appeal, where minimum unit sizes were required to be determined in the context of SEPP 65.


Clause 30A(1)(b) of SEPP 65 states:

(1) A consent authority must not refuse consent to a development application for the carrying out of residential flat development on any of the following grounds:


(b) apartment area: if the proposed area for each apartment is equal to, or greater than, the recommended internal area and external area for the relevant apartment type set out in Part 3 of the [Code].

[emphasis added]

The Court observed that it is only the MUS Table that contains recommended areas for both "internal" and "external" areas. The MUS Rule of Thumb refers only to a minimum total apartment area.

Further, the Court held that the term "relevant apartment type" was a clear reference to the nine apartment types identified in the MUS Table.

Although Botany Development submitted that the Code had been drafted with the "recommended minimums" contained within the Rules of Thumb (as held by the Court in the MPI Case), Sheahan J held that:

"... the language of the provision to be interpreted must take priority. Clause 30A(1)(b) refers to internal and external areas; hence, the only possible construction available for those words is that they were referring to the table, and not the Rules of Thumb."

[emphasis added]

For these reasons, the minimum areas referred to in clause 30A(1)(b) of SEPP 65 were to be found in the MUS Table and not the MUS Rule of Thumb.

As not all of the units within the Proposed Development met the minimum unit sizes in the MUS Table, the proceedings were remitted to Brown C for determination in light of the Court's findings.


In the context of clause 30A(1)(b) of SEPP 65, minimum unit sizes must be determined by reference to the MUS Table.

However, when considered in the absence of SEPP 65, such as in the MPI Case, minimum unit sizes will be determined by reference to the MUS Rules of Thumb.

This is an important distinction for both applicants for development consent and consent authorities.


Apartment Type



03.01 Studio

Internal Area



External Area


03.02 One bedroom,

Internal Area


cross through

External Area


03.03 One bedroom

Internal Area



External Area


03.04 One bedroom

Internal Area


single aspect

External Area


03.05 Two bedroom

Internal Area



External Area


03.06 Two bedroom

Internal Area


cross through

External Area


03.07 Two bedroom

Internal Area



External Area


03.08 Two bedroom

Internal Area


corner with study

External Area


03.09 Three bedroom

Internal Area



External Area


The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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