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PREPARED BY:NOR AZAH BINTI AZIZ
KOLEJ MATRIKULASI TEKNIKAL KEDAH
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An estimate is a calculation of the quantities of various items of work, and the expenses likely to be incurred there on.
The total of these probable expenses to be incurred on the work is known as estimated cost of the work. (close approximation of its actual cost)
The agreement of the estimated cost with the actual cost will depend on accurate use of estimating methods and correct visualization of the work, as it will be done.
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To give a reasonably accurate idea of the cost
An estimate is necessary to give the owner a reasonably accurate idea of the cost to help him decide whether the work can be undertaken as proposed or needs to be curtailed or abandoned, depending upon the availability of funds and prospective direct and indirect benefits.
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1. Estimating Materials
From the estimate of a work it is possible to determine what materials and in what quantities will be required for the work so that the arrangements to procure them can be made.
2. Estimating Labor
The number and kind of workers of different categories who will have to be employed to complete the work in the specified time can be found out from the estimate.
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3. Estimating Plant
An estimate will help in determining amount and kind of equipment needed to complete the work.
4. Estimating Time
The estimate of a work and the past experience enable one to estimate quite closely the length of time required to complete an item of work or the work as a whole. Whereas the importance of knowing the probable cost needs no emphasis, estimating materials, labor, plant and time is immensely useful in planning and execution of any work.
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Measuring- A process of evaluating items from
prepared working drawing n noting in the BOQ form.
- This evaluation is to obtain the items quantity in specific unit.
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Method of measuring are;i) linearii) areaiii) volumeiv) weightv) number
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Multiple items measured linearly Measure items with fixed cross section Estimate item price based on linear
item’s measurement such as length of pipe, length iof strip foundation and length of external wall of a building
Unit : metre ( m)
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Measure item such as pavement surface, plaster, brick wall, site clearing, formwork and so on
Measurement that is required to record are length and width, width and depth @ length and height.
Unit : squre metre ( m2)
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Involve item such as soil excavation for foundation, concreting for beam, slab and others
Sides measurement are length, width and depth for item with three surfaces
Structures like pyramids, cone, spherical and cylindrical require measurement based on mathematical formula to calculate volume.
Unit : cubic metre ( m3)10
Applied when item estimated is based on weight
Applied for item such as reinforcement steel placed in the reinforced concrete structure
Unit : kilogram to metric tonne ( kg to tonne)
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Applied for complex item where it is difficult to divide into small component and to estimate the price of each component.
Those items include electrical wiring such as lighting socket, fan point , door, window and precast concrete
Unit : Number ( No)
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Type of reinforcement
Hook (h) Bend (n) Symbol
Mild steel 12 d 8 d R or M.S
High- yield steel 15 d 9.5 d Y or H.Y
Table : Reinforcement steel measurement linear method
Diameter of reinforcement
kg/m
10 0.616
12 0.888
16 1.579
20 2.466
25 3.854
32 6.303
Table : Example of weight measurement of reinforcement13
Item’s cost is divided into:i) material costii) Labour costiii) plant and equipment costsiv) overhead cost and profit
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i) Material cost- Material cost such as brick, roof tile,
glass and iron- Estimated price depend on the
latest marker price and location of site.
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ii) Labour cost- A fee or wages to the workers after
work has been completed.
- Two classes of workers are;a. skilled workerb. general worker
- The determination of fee depends on the labour constant
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iii) Plant and equipment costs- Plant and equipment important to
execute work effectively and quickly.
- Two types;a. non machinery plant and equipment; ladder n wheel barrowb. machinery plant and equipment;
lorry, bulldozer n concrete mixer
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iv) overhead and profit cost- Include various type of payment related
to the company’s management;a. salary of management personnelb. cost and office equipment depreciation costc. allowances for company’s board of directors
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There are 5 methods of preparing estimation for
construction project;i) Volumeii) Floor areaiii) Evaluationiv) Approximate value quantitiesv) Bills of quantities
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- Based on the building length, width and height
- The construction cost of the proposed building is the product of the volume of the proposed building and the cost rate per cubic meter
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- Determined by multiplying the floor length to width ( measured from outer wall of the building)
- Construction cost of the new building = x
- Only considers the construction cost of the building.
- Other construction work such as fence, road, drainand landscape are not included.
Area of the new building
the cost rate per cubic metre of the existing building
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Carried out by counting the number of furniture, tools @ number of occupants.
For example, the unit to be calculated in construction of school is the number of chairs.
Every unit of the furniture is given the cost per unit based on the cost from the existing building.
Estimated cost = Cost per unit x Number of the furniture for proposed building
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Almost similar to the bills of quantities method Carried out by identifying items, calculating
quantity and calculating the item’s gross cost based on the working drawing.
Calculating cost are based on excavation work and concreting work.
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A bill of quantities (BOQ) is a
document
used in tendering in the construction
industry in which materials, parts, and
labor (and their costs) are itemized.
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It also (ideally) details the terms and
conditions of the construction or repair
contract and itemises all work to enable
a contractor to price the work for which
he or she is bidding.
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Most accurate method compared to the others method
QS take off accurately the quantity of measured items from the working drawing
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Step in preparing ;1. interpreting drawing2. dimensioning and taking off the quantities3. grouping of quantities4. estimating cost
BILL OF QUANTITIES METHOD
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Dimensioning and taking off quantities is a process of taking dimension, adding up and multiplying the items dimension.
Use the quantity measurement form- consist 2 parts- each part contains 4 column- they are multiplying, dimensions, total and work description columns.
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ADCBA
CB D
DIMENSION DIMENSION DESCRIPTIONDESCRIPTION
Record the number to be multiplied based on the number of repeated item
Record the dimension of items
Record the total measurement of linear, area, volume and number of items
Record the description operation of the measured items briefly n accurately
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ii) Area measurementTopsoil excavation 100 mm thick beginning from the ground level with 14.60 length and 12.60 width
Topsoil excavation 100 mm thick beginning from the ground level
183.96 mm2
183.96
14.6012.60
2.50
2.50
100 mm x 50 mm thick sawn and treated timber for roof rafter
2.50 m
DIMENSION DIMENSION DESCRIPTIONDESCRIPTION
i) Linear measurement 100 mm x 50 mm of thick sawn and treated timber for a 2.5 m long roof rafter
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iv) Weight measurementthe weight of steel reinforcement of 7m long with a diameter of 32 mm
32 mm in diameter mild steel reinforcement in column
x 6.303 kg/m = 44.191 kg
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22.02
22.00.701.30
excavating trench not exceeding 1.5 m deep
22.02 m3
DIMENSION DIMENSION DESCRIPTIONDESCRIPTION
iii) Volume measurement excavating trench not exceeding 1.5 m deep of 22.0 long, 0.70 wide and 1.3 deep
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5
5
Ceiling fan as described in the specification
DIMENSION DIMENSION DESCRIPTIONDESCRIPTION
v) Number measurement 5 number of ceiling fans
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Abstracting quantities is carried out by abstracting
Transfer all measurement and work descriptions from the dimension form to abstract form
Purpose of abstracting – to divide and group all particulars and work descriptions according to subheading and the quantities are rounded up
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Trench excavation for strip foundation beginning from the prepared level, not exceeding 1.50 m deep; backfilling the soil and compacting it; transporting and dumping surplus soil at an average distance of 50 m from the site.
Unit ( m3) page ( from the dimension form)
22.20 1
22.20 22 m3 ( rounded up to the nearest whole number)
When abstracting work is completed, the work description, unit and work quantities are recorded in the bills of quantities form top estimate the cost.
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Item
Description of work Unit Quantity Rate Total
RM Sen RM Sen
A Trench excavation for strip foundation beginning from the prepared level, nor exceeding 1.5 m deep; backfilling the soil and compacting it; transporting and dumping surplus soil at an average distance of 50 m from the site.
m3 22
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PROJECT :
