effective (equivalent) area (ea)


The area of each part of the building can be weighted according to value against the main so as to find the effective or equivalent area of the total building. The building is measured using the outside dimensions only. For example:

MAIN: 100% * 50 = 50.0

SKILLION: 80% * 30 =

24.0
VERANDAH: 30% * 15 =
4.5

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EQUIVALENT AREA: 

 78.5 m2


In the example above it is considered that the square metre ratio of the value of the skillion and verandah to the main is 80% and 30% respectively which approximates the respective value/m2 of these components. The value/m2 for a 2 or 3 storey house is less than an equivalent 1 storey house because the cost of the footings and roof are spread over the total floor area.