TOPIC 1: PRELIMINARY ESTIMATES

DEFINATION AND IMPORTANCE OF PRELIMINARY ESTIMATES

DEFINATION Defined as an activity in particular work to make

possible offer to execute task base on a stipulated sum

Technique to forecast the possible cost incurred for a certain building or construction project via a systematic calculation employing certain method, prepare at early stage of the project

Is a part of the cost planning process that is controlling of the project cost at the design stage before any drawings are embarked upon.

USE OF THE PRELIMINARY ESTIMATE METHOD

To ascertain the actual cost forecast of a project.

Assist the client in knowing to what extent he need to be financially committed to a particular project

Estimated is also function as a design guide whether the project to the allocation made either

Cont’d If the estimate is higher that the client

budget for that particular project, the following could be carried out :-

The design could be altered to reduce the cost

Extra provisions are sought after or requested from the client

The project is postponed or cancelled

Cont’d If the estimate is low than the allocated

sum, the following could be done

Accept the estimate

To modify the design and/or the specifications to increase the estimate appropriate to the provision set aside.

METHOD FOR PRELIMINARY ESTIMATE

UNIT

CUBIC

FLOOR AREA

METHOD WHEN IT IS USED

NOTEUNIT OF

MESUREMENT

UNIT Inception feasibility

Appropriate for project that have standard unit of accommodation, its commonly used to establish the cost limit for public sector project

Cost/studentCost/classroomCost/bedCost/ chair

CUBIC Outline proposal

Used to calculate the volume of air-conditioned space or space which is given mechanical ventilation

Cost/m3

FLOOR AREA

Outline proposalUsed extensively, can be used for almost all types of building

Cost/m2

THE SELECTION OF THE METHOD WILL DEPEND ON The information and time to prepare

the estimate

The experience of Quantity Surveyor

The total and type of cost data available

UNIT METHOD This method is also referred to as ‘cost according

to building function’

Estimate the building cost base on the size depends on the population unit

Example: the total number of student in a school, total number of bed in a hostel or hospital and etc.

Easier method but the most unrefined.

Total population can be obtained from the client or the design team

USAGE The cost estimate is obtained by multiplying

the number of accommodation for a new building with the cost per unit of accommodation based on a suitable building

The current unit of accommodation can be obtained by calculating from the sketch design or by obtaining information from the client.

Example:Estimate the total cost to build a mosque to house a congregation of 500 individuals.From a suitable cost data, get the cost/ congregation of a similar mosque that has been updated. Lets us say that the cost is RM 1400.00/ congregation.

Total cost = Number of accommodation x cost/congregation

500 individuals x 1,400 = RM 7000,000.00

CUBIC METHOD

In Malaysia this method is seldom or almost never used

Only in certain case, it is utilized To calculate the space which is need to

be air-conditioned To calculate the space that needs

mechanical ventilation

USAGE

Measure the volume of the new building and its volume is then multiplied with the suitable price rate per m3

Unrelated works is to be volume must be calculated separately

The volume of the building is calculated as follows:

Volume = length x width x height

i. Height of pitch rooffrom the top surface of the foundation to half apex / height of roof

ii. Height of flat roofFrom the top surface of foundation to

600mm above the flat roof or parapet wall (which is higher)

L

W

Flat roofPitch roof

ExampleEstimate the total cost to build a 2-storey bungalow if the construction cost/m3 of a similar construction is RM 550.00. estimate the construction cost base on

a) Pitch roofb) Flat roof

20.00

10.00

1.00

3.50

3.50

1.50

a) Pitch roofBuilding volume = 20.00 x 10.00 x [1.00 +2(3.50) + ½ (1.50)]

=20.00 x 10.00 x 8.75 =1750m3

Total building cost = volume x cost/m3=1750m3 x RM550.00=RM962,500.00

b) Flat roof

Building volume = 20.00 x 10.00 x [1.00 +2(3.50) + 0.60]

=20.00 x 10.00 x 8.60 =1720m3

Total building cost = volume x cost/m3=1720m3 x RM550.00=RM946,000.00

Floor area method Make a preliminary estimate as most of the cost

data are kept or are available in this form The measurement for GFA must be similar between

the new building and the analyzed building Need to consider criteria in measurement of area

In the calculation the floor area of a building there are several criteria need to be taken 1. The actual area of the building2. If the project offers a standard or different type of

accommodation it is better for each to be priced separately

3. Unrelated work to the area, for example, external work must be priced separately

Cont’d The rate per m2 chosen must be current rate as

building cost often differ

The site, external works, condition of contract, the quantity and the quality of equipment and others that related to the floor area must be calculated separately

It is clear and difficulty of this method lies in choosing the appropriate rate, which requires experience, observation and familiarity toward varied building types

USAGE The floor area of a building to be erected. Only

the building used this floor area method. Other works may use other method like approximate quantity.

Total cost = area x cost/m2 gross floor area (GFA)

Area – calculate the area of the building. The measurement method differs according to practices

Cost/m2 GFA – from similar building type and function

EXAMPLEEstimate the cost of the building by referring to the plans given if the construction cost is RM 1,500/m2 25.00

8.00

10.00 3.00

15.00

5.00

25.00

10.00

10.00

7.00

5.00

Ground floor plan First floor plan

CONT’DFloor areaGround floor25.00 x 5.00 = 125.0010.00 x 3.00 = 30.00 5.00 x 7.00 = 35.00

190.00

First floor25.00 x 5.00 = 125.0010.00 x 3.00 = 30.00 155.00

345.00

Total cost = area x cost/m2 Gross Floor Area

= 1500.00 x 345.00 = RM 517,500.00

UNIT CUBIC FLOOR AREA

Fast and easy Easiest method to

obtain cost limit to prepare the monetary allocations for several years to come

No necessity for drawings

The estimate can be prepared quickly

The client and architect easily understand the concept of floor area. most work items are appropriately associated with the concept of floor area rather than the volume method

Cost data easily available as most of the data from previous project most utilize this method

ADVANTAGES

DISADVANTAGESUNIT CUBIC FLOOR AREA

An unrefined method and in accurate. Only suitable to provide and overall approximate estimate

Does not take into account changes to plan, number of storeys and other factors related to design

Unrelated work concerning unit of accommodation has to be calculated separately.

Does not take into account changes to plan, height, of storey and the overall height of the building

Unrelated work to the volume has to be calculated separately

Does not help architect in design work as it is difficult to predict or to know the effects of the changes to specifications, design, etc. to the cost per m3

Difficult to obtain similar cost data

Does not take into account changes to plan, height, of storey and the overall height of the building as these factors effect the building cost

Other work which are not related to the floor area must be calculate separately

Difficult to calculate and allocate the cost for different site conditions, quality of materials, condition of contract and etc.