The shape of a
building has an important effect on
cost. As a general rule the simpler
the shape of a building, the lower
will be its unit cost. Let us
illustrate this as follows:
This determines the cost per square
meter of building
A. IRREGULAR
SHAPES
Example of how
building cost per square meter can
vary 
Cost per square meter
BUILDING A
Example of how
building cost per square meter
can
vary
BUILDING B
We note that both
plans have exactly the same floor
areas, yet building B is far more
expensive due to the shape of its
design. Reasons for the increase in
costs are:

Building B
has a higher perimeter/floor
area ratio (to be discussed in
more detail later) and
requires 6% more external
walling to enclose the same
floor area than A.

Setting out
costs will be increased by as
much as 50%.

Excavations
will cost between 6% and 20%
more.

Drainage
costs will increase by
approximately 25% due to the
extra manholes and extra length
of piping needed.

Additional
costs will also result from
other elements of the building
such as the walling and roofing
due to the work being
complicated by the shape.
It can therefore
be concluded that the irregular
shapes of buildings add to their
overall cost.
B. REGULAR
SHAPES
Regular shapes in
contrast, become more expensive the
longer and narrower they are
planned. This can be illustrated by
the following examples of a square
and rectangular building with the
same floor area.
BUILDING A
BUILDING B
Example of how
building
Cost per square meter can
vary
CASE A
Area on plan = 400m²
Length of walling = 80m
Assume 3m high walling @ Currency
200.00/m²
Then cost/m² = 80 x 3
x 200 ÷ 400
= Currency
120.00/m²  cost per
square meter
CASE B
Area on plan = 400m²
Length of walling = 208m
Assume 3m high walling @ Currency
200.00/m²
Then cost/m² = 208 x
3 x 200 ÷ 400
= Currency
312.00/m² 
cost per square meter
The length of
building B thus resulted in an
additional expense of Currency
76,800.00 over that of Building A
influencing
cost per square meter 