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**Taking off and ESTIMATING**

PREPARED BY: NOR AZAH BINTI AZIZ KOLEJ MATRIKULASI TEKNIKAL KEDAH

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ESTIMATING 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. Importance of correct estimating is obvious. Under-estimating may result in the client getting an unpleasant shock when tenders are opened and drastically modifying or abandoning the work at that stage. Over-estimating may lose the engineer or estimator his client or his job, or in any case his confidence. Estimating is the most important of the practical aspects of construction management, and the subject deserves the closest attention of one aspiring to a career in the profession. It is a comparatively simple subject to understand; however, as it brings one up against practical work, methods and procedure, knowledge of it cannot be acquired without close application.

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ESTIMATING 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. Importance of correct estimating is obvious. Under-estimating may result in the client getting an unpleasant shock when tenders are opened and drastically modifying or abandoning the work at that stage. Over-estimating may lose the engineer or estimator his client or his job, or in any case his confidence. Estimating is the most important of the practical aspects of construction management, and the subject deserves the closest attention of one aspiring to a career in the profession. It is a comparatively simple subject to understand; however, as it brings one up against practical work, methods and procedure, knowledge of it cannot be acquired without close application.

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ESTIMATING 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. Importance of correct estimating is obvious. Under-estimating may result in the client getting an unpleasant shock when tenders are opened and drastically modifying or abandoning the work at that stage. Over-estimating may lose the engineer or estimator his client or his job, or in any case his confidence. Estimating is the most important of the practical aspects of construction management, and the subject deserves the closest attention of one aspiring to a career in the profession. It is a comparatively simple subject to understand; however, as it brings one up against practical work, methods and procedure, knowledge of it cannot be acquired without close application.

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ESTIMATING 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. Importance of correct estimating is obvious. Under-estimating may result in the client getting an unpleasant shock when tenders are opened and drastically modifying or abandoning the work at that stage. Over-estimating may lose the engineer or estimator his client or his job, or in any case his confidence. Estimating is the most important of the practical aspects of construction management, and the subject deserves the closest attention of one aspiring to a career in the profession. It is a comparatively simple subject to understand; however, as it brings one up against practical work, methods and procedure, knowledge of it cannot be acquired without close application.

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**METHODS AND MEASURING UNITS**

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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**METHODS AND MEASURING UNITS**

Method of measuring are; i) linear ii) area iii) volume iv) weight v) number

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**Methods : Linear 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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**Methods : Area 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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**Methods : Volume 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)

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**Methods : Weight 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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**Methods : Number 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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**Methods : weight measurement**

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 reinforcement

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**TYPES OF COST Item’s cost is divided into: i) material cost**

ii) Labour cost iii) plant and equipment costs iv) overhead cost and profit

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TYPES OF COST 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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TYPES OF COST ii) Labour cost - A fee or wages to the workers after work has been completed. - Two classes of workers are; a. skilled worker b. general worker - The determination of fee depends on the labour constant

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TYPES OF COST 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 barrow b. machinery plant and equipment; lorry, bulldozer n concrete mixer

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**TYPES OF COST iv) overhead and profit cost**

Include various type of payment related to the company’s management; a. salary of management personnel b. cost and office equipment depreciation cost c. allowances for company’s board of directors

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METHODS OF ESTIMATING There are 5 methods of preparing estimation for construction project; i) Volume ii) Floor area iii) Evaluation iv) Approximate value quantities v) Bills of quantities

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**METHODS OF ESTIMATING - volume**

- 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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**METHODS OF ESTIMATING - floor area**

- 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, drain and landscape are not included. Area of the new building the cost rate per cubic metre of the existing building

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**METHODS OF ESTIMATING - Evaluation**

Carried out by counting the number of furniture, 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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**METHODS OF ESTIMATING - approximate value quantities**

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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**BILL OF QUANTITIES METHOD**

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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**BILL OF QUANTITIES METHOD**

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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**BILL OF QUANTITIES METHOD**

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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**BILL OF QUANTITIES METHOD**

Step in preparing ; 1. interpreting drawing 2. dimensioning and taking off the quantities 3. grouping of quantities 4. estimating cost

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**BILL OF QUANTITIES METHOD**

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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**Dimensioning and taking off quantitIES - DIMENSION FORM**

C B DIMENSION DESCRIPTION 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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Area measurement Topsoil excavation 100 mm thick beginning from the ground level with length and width Topsoil excavation 100 mm thick beginning from the ground level mm2 183.96 14.60 12.60 2.50 100 mm x 50 mm thick sawn and treated timber for roof rafter 2.50 m DIMENSION DESCRIPTION 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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**the weight of steel reinforcement of 7m long with a diameter of 32 mm **

Weight measurement the weight of steel reinforcement of 7m long with a diameter of 32 mm 32 mm in diameter mild steel reinforcement in column x kg/m = kg 7 22.02 22.0 0.70 1.30 excavating trench not exceeding 1.5 m deep 22.02 m3 DIMENSION DESCRIPTION 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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**Number measurement 5 number of ceiling fans**

Ceiling fan as described in the specification DIMENSION DESCRIPTION Number measurement 5 number of ceiling fans

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**ABSTRACTING 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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ABSTRACTING 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) m3 ( rounded up to the nearest whole number)

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ESTIMATING COST 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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**ESTIMATING COST PROJECT : RM Sen A**

Item Description of work Unit Quantity Rate Total 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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SOME COMMON RELATIONS USED IN BUILDING ESTIMATES

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