Building Depth

Building depth is an important tool for determining the development capacity of a site. It is the overall cross section dimension of a building envelope. Building depth dimensions typically include articulation such as projecting balconies, gallery access, eaves, overhangs, sun hoods, blades and other architectural features.

A mixed used building showing the transition of building depth: deeper floors on lower levels dedicated to retail/commercial uses and narrower residential apartments on upper levels 

Building depth influences building circulation and configuration and has a direct relationship to internal residential amenity by determining room depths, which in turn influences access to light and air. For residential development in general, narrower building depths have a greater potential to achieve optimal natural ventilation and daylight access than deeper floor plates. Depths of mixed use buildings transition from deeper commercial and retail uses at the lower levels to narrower building depths for the residential uses at upper levels.

These examples show how to measure building depth

for different apartment building shapes.

Aims

•  ensure that the bulk of the development relates to the scale of the desired future context

•  ensure building depths support apartment layouts that meet the objectives, design criteria and design guidance within the Apartment Design Guide.

Considerations In Setting Building Depth Controls

Building depth dimensions should include articulation such as projecting balconies, gallery access, overhangs, blades and other architectural features 

Use a range of appropriate maximum apartment depths of 12-18m from glass line to glass line when precinct planning and testing development controls. This will ensure that apartments receive adequate daylight and natural ventilation and optimise natural cross ventilation.

Test building depths against indicative floor plate and apartment layouts to ensure they can meet natural ventilation and sunlight requirements.

Site constraints may require varied building depths to achieve good levels of residential amenity for residents and neighbours.

Consider varying building depth relative to orientation. For example, buildings facing east-west capture sun from both aspects and may have apartments of up to 18m wide (if dual aspect), while buildings facing north-south should be narrower to reduce the number of south facing apartments that have limited or no direct sunlight access (consider relationship with section 4A Solar and daylight access). Where greater depths are proposed, demonstrate that indicative layouts can achieve acceptable amenity with room and apartment depths. 

This may require significant building articulation and increased perimeter wall length Coordinate building height and building depth:

•  buildings that have smaller depths over a greater height deliver better residential amenity than those with greater depth and a lower height

•  greater building depths may be possible where higher ceiling heights are provided, for example adaptive reuse of an existing building (see 4D Apartment size and layout).

For mixed use buildings, align building depth to the likely future uses. For example, transition deeper commercial or retail podium levels to a narrower residential tower above. For precinct planning, if the intended building use changes,the building depth needs to change accordingly. Set the depth control in metres. 

The building depth includes the internal floor plate, external walls, balconies, external circulation and articulation such as recesses and steps in plan and section.

Part 2 Developing The Controls

• Building Separation
• Street Setbacks
• Side And Rear Setbacks

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