What is the cost implications of design variables ./

wall / Floor Area Ratio

• Wall / floor ratio is a means of expressing the planning efficiency of a building and is influenced by the plan shape , size and storey heights .
• The ratio is calculated by dividing the external wall area ( inclusive of windows and doors ) by the gross floor area .
• The lower the wall / floor ratio , the more economical will be the proposal .
• The best wall / floor ratio is produced by a circular building but the saving is offset by bigger cost of circular work .

Circulation work

• An economic layout will have one of its main aim of reduction of circulation space because :

- circulation space such as entrace halls , staicases and corridors etc cannot be used for profitable purposes .

• The proportion of floor space allocated to circulation purposes vary between different tuypes of building .

- Office building 23% .

Storey height

• The storey heights of buildings are determined by the client's requirements
• The constructional items that are afected by the variation in storey heights would be :

1. Walls , parititons and their associated finishing works
2. Increased volume to be air-conditioning
3. Longer length of pipes or cables
4. Longer waste pipes to supply sanitary applicances
5. Possibility of higher roof costs due to increased in hoisting
6. Increased costs of constructing staircases and lifts
7. More costly foundations to supoort the increased load .