You are here: HomeRequirementsPlanning and Building GuideFloor Area Ratio

Floor Area Ratio is a measure of development intensity, which is expressed as a ratio of the gross floor area of a building to its total land area (net).  The purpose of this ratio is to control the bulk of a building and intensity of activity to a level, which is consonant with the level of existing or proposed infrastructure facilities.

To calculate this, if for example the land on which a building stands is 5,000 sq. ft. with a floor area ratio of 1:1, the allowable floor area of the building is: 5,000 sq. ft. x 1 = 5,000 sq. ft.

If the floor area ratio is 1:3, then the allowable floor area of the building is 5,000 sq. ft. x 3 = 15,000 sq. ft.

If the floor area ratio is 1:0.75, then the allowable floor area of the building is 5,000 sq. ft. x 0.75 = 3750 sq. ft.

While the floor area ratio may vary, the design of residential buildings should be so arranged as to enable the required floor space to be provided along with the consequent car ParkingBuilding Setbacks and any other Land Use and Development Plans requirements where appropriate, within this limit.

The recommended floor area ratios are:

  • Residential - 1:1 (high density)
  • Commercial - 1:3.0
  • Industrial - 1:0.75
  • Community facilities - 1:0.75

It is recommended that for developments outside of the town center, the Planning Authority may wish to vary the floor area ratios given above after examining the location and nature of the proposed development.