QUANTITY SURVEYING

QUANTITY SURVEYING

Definition: It is the series of technique of calculating or computing the various quantities and the expected Expenditure to be incurred on a particular work or project.

Importance of Quantity Surveying:

1. Estimate give 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.

Quantity Surveyor: Quantity surveying is an assessment of the cost based on certain rates of materials and Labour. An estimate should be realistic assessment should be made on actual conditions of market. Estimation is undoubtedly one or the most important aspects of a construction project. A good estimation saves the expenditure to a great extent and ensures optimum use of materials. Estimation is very much technical. It requires good knowledge on structural design, properly or engineering materials and essentially practical experience.

Essentials in a good Quantity Surveyor: What are the essentials in a good Quantity Surveyor? He must be able to describe clearly in proper unambiguous language the requirement of the Architect and so arrange his bill of quantities (BoQ) that the Builder can quickly, easily and accurately arrive at the estimated cost or the work. The Quantity Surveyor must have a sound knowledge or building materials and construction and or customs prevailing in the trade. He must be accurate in his work and calculations.

Procedure of Quantity Survey: Estimating involves the following operations

• Preparing detailed Estimate.
• Calculating the rate of each unit of work
• Preparing abstract of estimate

Preparing detail estimate: The following requirement are necessary for preparing a detail estimate.

a)    Drawings; like plan, elevation and sections of important points.
b)    Detailed specifications about workmen ship & properties of materials etc.
c)    Standard schedule of rates of the current year.

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.
Study of drawing: It would be extremely premature if an attempt were to be made at the taking on: immediately on receipt of the drawings. Much has to be accomplished before proceeding to take out quantities from the drawings. Many errors can be avoided if the following steps are taken before entertaining any thought of taking off:

(1) Look over the drawings and attempt to visualize the work entitled.

(2) Study the, are in    agreement with one another.

(3) Check drawings carefully to see that plans, elevations, sections and details, if any the dimensions on the drawings to make sure that each overall dimension agrees with the total room dimensions. If serious errors arc discovered, the architect should be informed; but if the discrepancy is due to the result of slight arithmetical error, the drawings should be corrected.

(4) If the dimensions do not exist in some places, then it is always better to write them in. These missing dimensions should be worked out from other dimensions, as far as possible, scaling them from the drawing being the last resort.

Specification: A Specification is a special description or a particular subject. An engineering specification contains detailed description or all workmanship and materials which are required to complete an engineering project in accordance with its drawings and details. The technical drawings of a structure will show, the proportions and relative positions of the various components of the structure. It is not often possible to furnish the information on the drawings, regarding the quality or materials to be used and the quality of workmanship to be achieved during construction, due to shortage of space. This data regarding the materials and workmanship is conveyed in a separate contract document, which is known as the "specifications" for the work. Thus the drawings with the specifications “will completely define the structure”. The “specification” is furnished separately along with the drawings and is an essential part of all engineering contracts. It should include below information.
 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.

Importance of specification: The importance of specifications are as follows:-

(a) The cost of unit quantity of work is governed by its specification.
(b) Specifications of a work are required to describe the quality and quantity or different materials required for a construction work and is one of the essential contract documents. Thus a contractor can make a programme to procure the materials required for a project and the owner can check the quality of materials conforming to the specification avoiding dispute with the contractor.
(c) This also specifies the workmanship and the method of doing the work. Thus specification of a work serves as a guide to the supervising staff of the contractor as well as to the owner to execute the work to their satisfaction.
(d) A work is carried according to its specification and the contractor is paid for the same. Any change in specification changes the tendered rate.
(e) As the rate or a work is based on specification, a contractor can calculate the rates of various items of works in a tender with his procurement rates of materials and Labour. Thus tender paper without specifications of works is baseless, incomplete and invalid.
(f)  Specification is necessary to specify equipment, tools and plants to be engaged for a work and thus enables to procure them beforehand.
(g) The necessity of specification is to verify and check the strength of materials for a work involved in a project.
(h) Specification is an essential contract document and required for arbitration of court cases

Schedule of 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 Labour, skilled or unskilled of masons, carpenters etc.

Rate analysis: It is important to analyze the rate of items of work individually to prepare the bill of quantities. The basis of arriving at a correct and reasonable rate per unit work or supply, for a particular item following its specification and detailed survey of materials, Labour, equipment, etc. as required for the unit work and their prevailing rates may be called as an analysis of rate.

Importance of Rate Analysis: Main importance of rate analysis are the following:-

(a) To determine the current rate per unit of an item at the locality. (b) To examine the viability of rates offered by contractors.
(c) To calculate the quantity of materials and labour strength required for the project planning.
(d) To fix up labour contracts rates.

The price of an item of work is made up of the following components and a summation of these is the rate per unit of an item.

(a) Cost of Materials
(b) Cost of Labour
(c) Cost or Equipment’s or Tools and Plants
(d) Cost of Overheads or Establishment Charges (including incidental) (e) Profit

Factors affecting the Rate analysis: The rate of an item of work mainly depends on the following factors:-

(1) Specification of the item which indicates the quality and proportion of materials, the method of construction and protection of work.
(2) The present art of materials for the item of work up to the work site.
(3) Daily wages of different categories of laborer at the locality with their respective outputs.     (4) The range of lead and lift required for deposition of materials to carry out the item or work.
(5) Percentage charge of overheads which includes insurance and the possibility of theft or loss, etc.
(6) The range of profit and availability of water in connection with the construction work.

Besides these the site condition, site organization and cost control during execution etc. should be considered as these factors affect the cost per unit of work done at site.

Flow chart of Quantity survey: Most of people think that the estimate of a structure includes cost of land, cost of materials and Labour, but many other direct and indirect costs included and is shown below.

LUMPSUM:
While preparing an estimate, it is not possible to work out in detail in case of petty items. Items other than civil engineering such items are called lump sum items or simply 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.

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.

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. An L.S. amount of 1½ to 2% of the estimated cost is provided towards the work charged establishment.