HOW BUILDING DESIGNS CAN INFLUENCE ITS BUILDING COST?
DESIGN FACTORS
Do you know that there are a lot of factors that can influence the building cost? Cost of a building can be influenced by these factors:
Figure 1: Factors that can influence the building cost.
Based on the chart above, Design team
plays an important role to control the cost of a building. Design team can “help”
the owner or investor of a building to get the best value of money out of the
construction cost. The cost does not have to be cheap but at least economical.
Economical building is a building that gives value at the lowest cost but can fulfil
the design and function required.
1. Building Plan Shape
The plan building shape is important to determine the building
cost.
|
Building Shape |
Pros |
Cons |
|
Circular |
· Economical · Provides bigger volume with the
minimum enclosing wall |
· The building function is limited. |
|
Big Square |
· Economical |
· Not practical · Suitable for room such as stores
and warehouses. |
Table 1: Pros and cons of building plan shape
Though the circle is the most efficient enclosure of
space, the cost of building circular work makes it more costly. So, the most
economic building shape is square and more a building shape retreats from the
square shape the cost of external envelop increases in relation to the
remaining building cost.
When a building becomes longer and narrower or
irregular, the wall area will be increased due to the increase of perimeter,
which causes a higher cost of construction. In an irregular shaped
building, the cost increases due to the greater cost for scaffolding areas,
complexity in setting out of the project, and difficulty in cleaning and
maintaining the building.
Generally, a building
plan with a simple shape will be the most economical.
2. Building
Size
Generally, when the
building size is increase, the unit cost will be decreased, this is because the
greater the floor area will give the lower cost per square meter. Ordering
material in a large scale can also reduce in unit costs of materials.
3. Building
Storey Height
Height of a building
can be changed, subject to regulations (the Street, Drainage and Building Act).
There are few major costs that will be change when the storey height is changed
such as:
· Construction
cost for the foundation and structural frames will increase due to increase in
load on the foundation.
· Adding
height of a building would need to also add stairs, escalators, and lift. All
these needs cost.
· Cost
for increasing quantity of internal wall, external wall and wall finishes.
· Ceiling
construction.
· Installation
of air-conditioning system.
· Installation
cost of electrical wiring and piping for water supply.
· Maintenance
cost repainting works, cleanings of walls, operation cost of air-conditioning.
4. Building
Total Height
Total cost of a
building varies according to its height. Tall building is more expensive to
build compared to a two or three storey building height. This is because, tall
building needs building services such as escalator, lifts, and cranes.
5. Circulation
Area
The gross floor area
and net floor area should be as close as possible. Multi-storey building that
needs stairs, lift, refuse chute and ducts will need more space which would be
included in the net floor area.
SITE FACTORS
The shape and the size of
the site also determines the building plan shape and size.
1.
Effect of Site on Building Size
The
small size of site will limit the shape and design of the building. Thus, the
developer is advised to buy the adjacent site so that the development is more economical.
This is better than having a weird shape and size of building due to limited
size of site.
2.
Effect of Site on Design of Building
The building
size also can be influenced by the site. There are many buildings that have
weird shape to maximize the site. For example, the Bank Rakyat building was
built in a weird looking shape because of site factor.
3.
Effect of Site on Plot Ratio
The
plot ratio is the ratio of the site area with the total construction area. The
total construction ratio is calculated by totalling the gross floor area on all
levels.
4.
Effects of Site Condition on Design
Different
site condition required different types of foundation. For example, land that
has 600kn/m2 may be supported by pad foundation. Site that consist
more water content in the soil needs a special type of foundation.
References
Ahmad, K. H. (2011). Construction Economics. Kuala
Lumpur: Pearson Malaysia Sdn Bhd.
Comments
Post a Comment