Read the controls as a set
Setbacks, floor area and building height help shape a proposal, but none should be considered in isolation. A design may meet a floor area limit and still need changes to its building position, access, outdoor space or relationship with neighbours.
Begin by identifying the development type and likely approval pathway. A dwelling, dual occupancy and secondary dwelling can involve different provisions. The number used for a nearby project may have been assessed under a different policy, at a different time or on a different site.
Ask your designer to record the source of each control and any assumptions that remain unresolved. This creates a common reference for the concept, area schedules and discussions with the town planner or certifier.
What a setback tells you
A setback describes a required separation between a building or building element and a relevant boundary or reference point. Front, side and rear controls can affect the available building envelope in different ways.
Check which part of the building is being assessed. Walls, garages, upper floors and projections may need different treatment under the applicable provisions. A single dimension on a site plan may not demonstrate the whole proposal.
Use a reliable survey and label the relevant dimensions clearly. Where a requirement depends on neighbouring buildings or another reference, confirm what evidence is needed and how the measurement is to be taken. Do not assume a front setback can be selected simply because it looks consistent with the street.
What floor space ratio means
Floor space ratio, or FSR, relates the assessable gross floor area to the relevant site area. It is a density measure rather than a description of the building footprint. NSW Planning's explanation of the planning system illustrates how floor space can be distributed across different numbers of storeys.
For an arithmetic example only, a 600 square metre site assessed at an FSR of 0.5 to 1 would correspond to 300 square metres of assessable gross floor area, assuming that site area is the correct basis. This example does not state the permissible FSR for any particular property.
The same total could be arranged in different ways across floors. However, setbacks, height, landscaping and other controls may prevent some arrangements. An FSR calculation is one part of the design check.
What gross floor area means
Gross floor area, or GFA, is a defined planning measurement. It should not be assumed to equal a builder's advertised total area, the sum of room sizes or a measurement to the outside of every wall.
For example, the NSW Planning Portal's Housing Code guidance describes GFA as measured from the internal face of external walls, or relevant separating walls, at a height of 1.4 metres above the floor. The complete definition and applicable inclusions and exclusions still need checking for the proposal.
Prepare an area plan and schedule using the correct assessment basis. Identify included and excluded areas rather than presenting only one total. Where another rule uses a different area measure, calculate it separately and label it clearly.
Why DA and CDC area checks may differ
For a DA, identify the planning instruments and controls relevant to the proposed development. For complying development, identify the applicable code and the area limits and definitions it uses. Avoid carrying one pathway's figures into another without checking them.
The interaction of state and local provisions can also matter. The Low and Mid-Rise Housing Policy summary sets out non-discretionary standards for specified development in eligible areas. Their existence does not mean those figures apply to every NSW site or create automatic CDC eligibility.
If you are comparing pathways, ask for an explanation of how each would affect the building envelope and brief. The best option may depend on room arrangement and buildability as much as the maximum calculated area.
Check combined dwelling proposals carefully
Where a principal dwelling and secondary dwelling are proposed together, review the relationship between their area allowances and the relevant site requirements. Do not assume that a secondary dwelling's nominated size can simply be added to the maximum allowable area of the principal house.
NSW Planning notes that the site requirement calculations for secondary dwellings approved as complying development include the principal dwelling, secondary dwelling and specified attached structures. Read the official secondary dwelling guidance.
Your area schedule should therefore identify the different components of the proposal and the basis used for each check. Read our granny flat guide for the wider site and design considerations.
Building height needs accurate levels
Height should be checked using the measurement method required by the applicable controls. A reference to the number of storeys alone does not establish compliance.
A sloping site makes accurate survey levels particularly useful. The building's relationship to the ground can change across its footprint, and concept floor levels influence access, excavation and the appearance of the building. Ask the designer to show the relevant levels and height checks in suitable sections and elevations.
Do not leave levels as a late drafting exercise. Coordinating them with the survey and engineering advice can avoid a layout that later requires substantial redesign. Our existing sloping-site guide discusses the broader design issues.
Site coverage and landscaping are different measures
Site coverage concerns the portion of land covered by the buildings or structures counted under the applicable definition. Landscaping and private open space checks have their own requirements. They should not be treated as interchangeable with GFA.
During concept design, mark the main area checks separately. This can reveal that a driveway, outdoor structure or parking arrangement affects the site differently from the enclosed dwelling floor area.
For an owner, the practical benefit is a clearer picture of usable space. A proposal with a large calculated dwelling area may leave outdoor spaces that are difficult to use. Testing furniture, circulation and garden access alongside compliance checks helps develop a more useful layout.
Bring uncertainties into the discussion early
If a control is unclear, resolve the interpretation with the appropriate planner or certifier before extensive documentation. Ask what evidence supports the assessment and keep a written record of the response.
Changes to the brief, building position or title configuration can require the controls to be checked again. An early assessment is tied to its assumptions. Keep the area plans and compliance schedule current as revisions are made.
Develop a checked concept with iRoom Design
iRoom Design assists with feasibility, concept design and coordinated documentation for NSW homes, duplexes and other projects. We can help organise the site and area information and engage the relevant specialists where necessary.
Contact us with the address, survey and intended development. For the broader approval comparison, read our DA versus CDC guide.
General information only. Numerical examples are illustrative; current site-specific provisions and definitions must be verified.