Cost Planning – Statements about economical building design Which of the following statements about minimizing building cost is correct?

Introduction / Context:
Architectural planning and structural decisions strongly influence project cost. Geometry, number of storeys, and vertical dimensions determine quantities of high-cost elements such as external walls, foundations, and roofing.

Given Data / Assumptions:

• Comparison of plan shapes for a fixed usable area.
• Choice between single-storey and double-storey solutions for the same total built-up area.
• Typical residential or small commercial construction.

Concept / Approach:
For a fixed area, a square has the least perimeter; external walling and foundation length scale with perimeter, so square rooms reduce material and labour. Stacking floors shares the same foundation footprint and reduces total roof area per unit floor area; hence two storeys lower the proportionate cost of foundations and roofing. Excessive storey height increases wall volume, formwork, and services runs, so limiting height within functional needs reduces cost.

Step-by-Step Solution:
Geometric efficiency: square plan ⇒ minimum external envelope per area.Vertical stacking: double-storey ⇒ one roof over two floors; same foundations support more area.Vertical dimensioning: lower heights ⇒ less wall and service materials.

Verification / Alternative check:
Elementary cost models decompose cost into foundation, superstructure, roof, and finishes. For equal built-up area, perimeter-dependent items decrease with compact shapes, and roof/foundation proportions drop when floors are stacked.

Why Other Options Are Wrong:

• Options a–c are all valid considerations; “None of these” is incorrect.

Common Pitfalls:
Ignoring circulation and fenestration requirements that might offset geometric savings; nevertheless, the listed principles are broadly correct in preliminary cost planning.

Final Answer:
All of the above