Question

An existing four storey building of identical floor plans was built by utilizing the maximum allowable F.A.R. and maximum ground coverage of 50% in a plot of 500 m\(^2\). Due to incentive zoning, the F.A.R. of the plot has been increased to 2.75. The maximum floor area (in m\(^2\)) that can now be added to the building is (in integer).

Hint:

Find the existing built-up area from the 50% ground coverage over 4 floors, then subtract it from the new permissible area (2.75 x plot area).

Answer 1

Correct Answer: 375

Step 1: Think in terms of the change in F.A.R. directly.
Instead of first finding the original F.A.R. from the footprint and floor count, we can reason about the jump in F.A.R. itself. The plot area stays fixed at $500$ m$^2$ throughout.

Step 2: Find the built-up area used originally.
The footprint is $50\%$ of $500$ m$^2$, so each floor covers $250$ m$^2$. With 4 identical floors:
$$\text{Original built-up area} = 4 \times 250 = 1000 \text{ m}^2$$
This is the amount of floor area the plot's original F.A.R. allowed.

Step 3: Express the original F.A.R. as a check.
$$F.A.R._{original} = \frac{1000}{500} = 2.0$$

Step 4: Find the gain in F.A.R.
$$\Delta F.A.R. = 2.75 - 2.0 = 0.75$$

Step 5: Convert this gain in F.A.R. directly into extra floor area.
Since F.A.R. is built-up area divided by plot area, the additional floor area unlocked equals the F.A.R. gain multiplied by the plot area:
$$\text{Extra area} = 0.75 \times 500 = 375 \text{ m}^2$$
This matches the answer found by subtracting the old built-up area from the new total permissible area.

Final Answer:
An extra 375 m$^2$ of floor area can now be added to the building.