Estimation And Costing (a70138)


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LECTURE NOTES
ON
ESTIMATION AND COSTING (A70138)
IV B. Tech I Semester (JNTUH-R15)
By Mr. Gude Ramakrishna
Associate Professor
DEPARTMENT OF CIVIL ENGINEERING
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
DUNDIGAL, HYDERABAD - 500 043

UNIT - I
INTRODUCTION
TECHNICAL TERMS
1. ESTIMATE:An estimate is the anticipated or probable cost of work and is usually prepared before the construction is taken up. It is indeed calculations or computations of various items of an engineering work.
2. QUANTITY SURVEY: It is the schedule of all items of work in a building. These quantities are calculated from the drawing of the building. Thus quantity survey gives quantities of work done in case of each items, when priced gives the total cost. In short, quantity survey means calculations of quantities of materials required to complete the work concerned
3.SPECIFICATIONS :Detailed specifications gives the nature, quality and class of work, materials to be used in the various parts of work , quality of the material, their proportions, method of preparation, workmanship and description of execution of work are required.
4.RATES :The rates of various items of works, materials to be used in the construction and the wages of different categories of labor (skilled and unskilled) should be available for preparing an estimate. The cost of transportation charges should also be known. As far as possible sanctioned “Schedule of Rates” shall be followed or the rates may be worked out by the “Analysis of Rates” method.
5.SITE PLAN: It is the plan drawn for a particular construction showing its position with respect to approaching roads, main bazars, markets and other permanent features in a populated area. It shows the location of the area under construction with respect to the other areas and on it generally the names of the owners of areas or property holders adjoining to it are also denoted. North line is also clearly marked on it.
6. LINE PLAN Line plan can be defined as the plan of a particular construction simply showing main features with the help of the single lines of different portions of the constructions. Details of constructions are not generally shown on this plan. This inside and outside dimensions shown on this plan should necessarily be corresponding to actual dimensions.
7. INDEX PLAN :This is the plan of a particular colony showing the positions of different houses in single lines their number if any position of roads, schools, market, hospitals and other features etc. this plan is generally fixed on the entrance, or at exit or in the central place of the colony, for the guidance of the inhabitants and outsiders.
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DETAILED PLAN : This plan indicates a plan of a construction drawn to a definite scale, showing all detailed information required for its execution. Various sections and elevations are clearly drawn on this plan.
CENTRE LINE PLAN : This is actually a layout plan drawn to facilitate the laying out of foundation lines and other features. It is generally fixed on the entrance or at exit in the central place of the colony for the guidance of the inhabitants and outsiders.
SUPPLEMANTARY ESTIMATE: When some additions are done in the original work, a fresh detailed estimate is prepared to supplement the original work. This estimate is called supplementary estimate. It is also accompanied by all the papers as required in thru detailed estimate.
ADMINISTRATIVE APPROVAL: For any project required by the department an approval so sanction of the competent authority with respect to the cost and work is necessary at the first instance. Thus administrative aooroval denotes the formal acceptance by the administrative department concerned of the proposals for incurring expenditure.
TECHNICAL SANCTION :It means the sanction and order by the competent authority of the department for the detailed estimate design calculations quantities of work rates and cost of work..after the technical sanction of the estimate is received the work is then taken up for construction.
COMPETENT AUTHORITY: An officer or any other authority in the department to whom relevant powers are delegated by the government (Financial Department).
ORDINARY MEASUREMENT BOOK: It is measured book in which entries regarding the work done or supplies made and services performed are recorded for the purpose of making payments to the contractors or the labor. Entries in the M.B are generally recorded by the sectional officers or by any other officers deputed for the purpose
LUMPSUM ITEMS
Sometimes while preparing estimate for the certain small items like front architecture or decoration work of a building it is not possible to workout detailed quantities so far such lump sum items a lump sum rate is provided. PLINTH AREA
The built up covered area of a building measured at floor level of any storey is called plinth area.
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17. CIRCULATION AREA The total cost of construction including all expenditures incurred plus the cost of external servicesup to the end of the completion of the work is called capital cost. It also includes the cost of preliminary works, miscellaneous items and supervisioncharges etc. 1.1 GENERAL Estimating is the technique of calculating or computing the variousquantities and the expected Expenditure to be incurred on a particular work orproject. In case the funds available are less than the estimated cost the work isdone in part or by reducing it or specifications are altered, the following requirementare necessary for preparing an estimate.
1. Drawings like plan, elevation and sections of important points. 2. Detailed specifications about workmanship& properties of materials etc. 3. Standard schedule of rates of the current year. 1.2UNITS OF MEASUREMENTS The units of measurements are mainly categorized for their nature, shape and size and for making payments to the contractor and also. The principle of units of measurements normally consists the following: a) Single units work like doors, windows, trusses etc., is expressed in numbers. b) Works consists linear measurements involve length like cornice, fencing, hand rail, bands
of specified width etc., are expressed in running meters (RM) c) Works consists areal surface measurements involve area like plastering, white washing,
partitions of specified thickness etc., and are expressed in square meters (m2)
d) Works consists cubical contents which involve volume like earth work, cement concrete, Masonry etc are expressed in Cubic metres.
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1.2.1 RULES FOR MEASUREMENT The rules for measurement of each item are invariably described in IS- 1200. However some of the general rules are listed below.
1. Measurement shall be made for finished item of work and description of each item shall include materials, transport, labor, fabrication tools and plant and all types of overheads for finishing the work in required shape, size and specification.
2. In booking, the order shall be in sequence of length, breadth and height or thickness. 6

3. All works shall be measured subject to the following tolerances. I. linear measurement shall be measured to the nearest 0.01m. II. Areas shall be measured to the nearest 0.01 sq.m III. Cubic contents shall be worked-out to the nearest 0.01 cum
4. Same type of work under different conditions and nature shall be measured separatelyunder separate items.
5. The bill of quantities shall fully describe the materials, proportions, workmanships and accurately represent the work to be executed.
6. In case of masonry (stone or brick) or structural concrete, the categories shall be measured separately and the heights shall be described: a) From foundation to plinth level b) From plinth level to first floor level c) From Fist floor to second floor level and so on.
1.3 REQUIREMENTS OF ESTIMATION AND COSTING 1. Estimate gives an idea of the cost of the work and hence its feasibility can be determined i.e. whether the project could be taken up with in the funds available or not. 2. Estimate gives an idea of time required for the completion of the work. 3. Estimate is required to invite the tenders and Quotations and to arrange contract. 4. Estimate is also required to control the expenditure during the execution of work. 5. Estimate decides whether the proposed plan matches the funds available or not.
1.3.1 PROCEDURE OF ESTIMATING OR METHOD OF ESTIMATING. Estimating involves the following operations 1. Preparing detailed Estimate. 2. Calculating the rate of each unit of work 3. Preparing abstract of estimate
1.3.2 DATA REQUIRED TO PREPARE AN ESTIMATE 1. Drawings i.e. plans, elevations, sections etc. 7

2. Specifications. 3. Rates. 1.3.3 DRAWINGS If the drawings are not clear and without complete dimensions the preparation of estimation become very difficult. So, it is very essential before preparing an estimate.
1.3.4 SPECIFICATIONS General Specifications: This gives the nature, quality, class and work and materials in general terms to be used in various parts of wok. It helps no form a general idea of building.
Detailed Specifications: These gives the detailed description of the various items of work laying down the Quantities and qualities of materials, their proportions, the method of preparation workmanship and execution of work.
1.3.5 RATES For preparing the estimate the unit rates of each item of work are required. 1. for arriving at the unit rates of each item. 2. The rates of various materials to be used in the construction. 3. The cost of transport materials. 4. The wages of labor, skilled or unskilled of masons, carpenters, Amador, etc.,
1.3.6COMPLETE ESTIMATE Most of people think that the estimate of a structure includes cost of land, cost of materials and labor, but many other direct and indirect costs included and are shown below.
L.S.Items.
The following are some of L.S. Items in the estimate. 1. Water supply and sanitary arrangements. 2. Electrical installations like meter, motor, etc., 3. Architectural features. 4. Contingencies and unforeseen items.
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In general, certain percentage on the cost of estimation is allotted for the above L.S.Items Even if sub estimates prepared or at the end of execution of work, the actual cost should not exceed the L.S.amounts provided in the main estimate. 1.3.8 WORK CHARGED ESTABLISHMENT: During the construction of a project considerable number of skilled supervisors, work assistance, watch men etc., are employed on temporary basis. The salaries of these persons are drawn from the L.S. amount allotted towards the work charged establishment. That is, establishment which is charged directly to work. AnL.S.amount of 1½ to 2% of the estimated cost is provided towards the work charged establishment.
1.4 METHODS OF TAKING OUT QUANTITIES
The quantities like earth work, foundation concrete, brickwork in plinthand super structure etc., can be workout by any of following two methods:
a) Long wall - short wall method
b) Centre line method.
c) Partly centre line and short wall method.
1.4.1 LONG WALL-SHORT WALL METHOD
In this method, the wall along the length of room is considered to be longwall while the wall perpendicular to long wall is said to be short wall. To get thelength of long wall or short wall, calculate first the centre line lengths of individual walls. Then the length of long wall, (out to out) may be calculated after adding half breadth at each end to its centre line length. Thus the length of short wall
Measured into in and may be found by deducting half breadth from its centre linelength at each end. The length of long wall usually decreases from earth work tobrick work in super structure while the short wall increases. These lengths aremultiplied by breadth and depth to getquantities.
1.4.2 CENTRE LINE METHOD This method is suitable for walls of similar cross sections. Here the totalcentre line length is multiplied by breadth and depth of respective item to get thetotal quantity at a time. When cross walls or partitions or verandah walls joinwith main all, the centre line length gets reduced by half of breadth for eachjunction. Such junction or joints are studied carefully while calculating total centreline length. The estimates prepared by this method are most accurate and quick.
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1.4.3 PARTLY CENTRE LINE AND PARTLY CROSS WALL METHOD This method is adopted when external (i.e., around the building) wall isof one thickness and the internal walls having different thicknesses. In such cases,centre line method is applied to external walls and long wall-short wall method isused to internal walls. This method suits for different thicknesses walls and differentlevel of foundations. Because of this reason, all Engineering departments arepracticing this method. 1.4.4 DETAILED ESTIMATE The preparation of detailed estimate consists of working out quantities of various items of work and then determines the cost of each item. This is prepared in two stages. I) DETAILS OF MEASUREMENTS AND CALCULATION OF QUANTITIES The complete work is divided into various items of work such as earth work concreting, brick work, R.C.C. Plastering etc., The details of measurements are taken from drawings and entered in respective columns of prescribed preformed. The quantities are calculated by multiplying the values that are in numbers column to Depth column as shown below:
Details of measurements form
ii)
Abstract of Estimated Cost: The cost of each item of work is worked out from the quantities that already computed in the details measurement form at workable rate. But the total cost is worked out in the prescribed form is known as
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Estimation And Costing (a70138)