How to calculate yield for an Apartment Building

One of the first things you need to know when considering a site is how many apartments can be built on it, this will help determine if the site is feasible. 

1. Get information about the site following the steps above. The main information that you need to check is if apartment buildings are permitted in the zone (found in the LEP), what the height limit is (found in property portal and the LEP) and the rear and front setbacks (found in the DCP). These can all be found easily on Mecone Mosaic Mapping:

https://www.mecone.com.au/mosaic/

2. Find the side setbacks required. In the Apartment Design Guide (ADG) the side setbacks are:

9 storeys and above 12m setback (12-24m separation)

Up to 8 storeys 9m setback (9-18m separation)

Up to 4 storeys 6m setback (6-12m separation)

These are the setbacks to habitable spaces, they are the best to use in feasibility as council often won't accept the non habitable spaces.

3. Get a scaled map from sixmaps. 

4. Draw in the setbacks. 

5. Calculate the area inside the setbacks and multiply it by as many levels as will fit under the height limit. Allow 3.4m from floor to ceiling. Look at the contours on sixmaps to take into account half levels.

6. When you have the area remove 20% from it to allow for corridors and foyers.

7. This number is an approximate Ground Floor Area (GFA).

8. Go to the LEP and check what the maximum Floor Space Ratio (FSR) is for the site. FSR is GFA/ site area.

9. The Ground floor area you can use is either the one you have calculated with the setbacks or the site area x FSR - whichever is lesser.

10. Divide this number by the following numbers to get an estimate of how many apartments the site will yield (these numbers are greater that the minimum required by the ADG to allow for balconies and wasted space):

3 bed: 120m² (ADG minimum 90m² + 5m² for second bathroom)

2 bed 100m² (ADG minimum 70m² + 5m² for second bathroom)

1 bed 70m² (ADG minimum 50m² + 5m² for second bathroom)

studio 50m² (ADG minimum 30m²  + 5m² for second bathroom)

11. A good shortcut is to calculate the number of two bedrooms GFA/ 100m² and then work out an apartment mix later.

12. This will give you a rough idea, councils are very strict on solar access and natural ventilation compliance with the ADG so get your local architect to check that you can comply.