Construction Cost Estimating


Details about floor area and site coverage

Given below, the detail information on the floor area and site coverage which should be included in a floor plan.

Lot area: The entire square footage of a property.

Floor area : The entire square footage of a house. It is calculated to the exterior face of the building envelope along with 2nd storey covered balconies and trellises which expand in excess of 1.2 metres (m) from the exterior face of the building (covered section only).

Floor Area Ratio (F.A.R.): The figure is derived when the entire proposed floor area of all stories and attics of the principal building and all associate buildings is divided with the site area.

Floor area is equivalent to length x width for both floors that is calculated to the exterior face of the wall, whether a floor exists or not.

Different types of spaces like stairwells, elevator shafts, openings to the storey underneath are comprised in the floor area.

The following areas are not included in floor area measurement :-


The portions of the basement are partly or completely eliminated from F.A.R.:

  1. Any part of the basement that expands apart from the exterior walls of the storey over, along with crawl spaces, counts 100% in F.A.R calculations—none of this area are discarded.
  2. The floor area of basement is fully excluded from F.A.R. where the key floor elevation is 0.9m or less over the lower of natural or finished grade at the perimeter walls.
  3. To find out the basement area exemption, average natural and projected grades should be computed.
  4. Other parts of the basement are partly excluded from F.A.R., on the basis of the following calculation:
  5. Lowest average grade – basement floor elevation /main floor elevation – basement floor elevation x 100

  6. This percentage should be multiplied with the total area of the basement to which this exclusion is employed to obtain the amount of area that is excluded from F.A.R. calculations.

  7. This calculation should be reiterated for each segment of the basement if floor elevation differs.

A Garage or Carport: Whether related to, isolated from, or portion of the principal dwelling to a maximum of 41m2 . When the garage remains in the basement, its area is excluded while measuring the basement area exemption.

An Accessory Building: For instance a tool shed or pool house, to a max of 22.5m2 , if situated 4.5m or more from principal building; max 4.6m2 is excluded if closer than 4.5m.

Decks and Porches: Exposed parts only. 2nd storey covered decks, expanding in excess of 1.2m from the exterior face of the building, are not excluded.

Attic space: Below 1.7m in height, calculated from the underneath of roof sheathing to the top of the ceiling joist or floor joist.

Crawl spaces: Under 1.8m in height (top of the ground to the underneath of floor joists over). Constructed Floor levels lifted for non-structural purposes cannot be taken into consideration for this exemption.

Unenclosed Landscape features: like open trellises, gazebos and patios.

Site coverage: The percentage figure derived when the total proposed area of all buildings and structures is divided with the site area.

For site coverage calculations, the following areas should be included :

  1. The principal dwelling, along with porches
  2. Exterior steps and decks which are included or more than 0.6m over grade
  3. The garage
  4. Enclosed, covered walkways
  5. Associate buildings or structures
  6. The pools over ground
  7. Source:

    Details about floor area and site coverage