How do I calculate floor space ratio of my development?

The floor space ratio is a development standard which is referenced in clauses 4.4 and 4.5 of Mosman LEP 2012 and controls the bulk and scale of buildings.

To calculate the floor space ratio for your development you will need to know:

  1. The site area
  2. The allowable floor space ratio for the site which is identified on the Floor Space Ratio Map
  3. The gross floor area of the development (this is defined in the Dictionary of Mosman LEP 2012)

The floor space ratio is the ratio of the gross floor area of a development to the site area expressed as a factor of 1. That is, the total floor area on all levels of the building minus any exclusions provided for in the definition of gross floor area, divided by the site area.

For example:

site area – 600m2
gross floor area – 300m2
calculation – 300m2 divided by 600m2 = 0.5
This provides for a floor space ratio of 0.5:1

It should be noted that the definition of gross floor area allows for the exclusion of car parking to meet any requirements of Council. Part 5.10 of Mosman’s Residential DCP specifies that for dwelling houses, a minimum of 1 space is required. Contact Council’s Duty Planner on 9978 4172 to discuss the specifics of your proposal as necessary.