Quantity Survey Definition and Methods

Quantity Survey

Modern quantity surveyors provide services that cover all aspects of procurement, contractual and project cost management. They can either work as consultants or they can be employed by a contractor or sub-contractor.

The main role of Quantity Surveyors is to estimate the building cost. Each building can be divided into different parts, cost of each part can be estimated and by adding cost of all parts of building together will give contractors an estimated cost for the whole work. It's been proved in practice that by adding cost of quantities, material used for project and labour will provide us with the total cost of the project. We must not forget that the bill provided by quantity surveyor is an estimate and it is prepared before any work starts to give a contractor estimated cost. Contractor then agrees to do the work based on the estimated cost that represents the proposed work.

Position of Quantity surveyor came available after builders realized how much work it requires to do all the measurements and calculations and it would be much more cost effective for them all to employ one person to do it. As soon as they implement this in practice architects and employers soon realized the effectiveness of quantity surveyors.

As we've already learned above the estimated cost of construction work prepared by quantity surveyor is used for tendering. Each builder can therefore price the work that needs to be done based on same bill of quantities and this is what gives building industry a healthy competition.

Every good quantity surveyor must have a good knowledge of building materials and construction. Surveyor must be very systematic and careful to provide correct calculations as well as be able to visualize drawings and details. To make sure that the quantity bill is accurate, surveyor needs to be sure of all requirements of architects. Arranged bill needs to be clear and easily understood to prevent any costly misunderstandings.

There is basically two method's

1) Rough cost estimate  

2) Detailed cost estimate   

Requirements for Estimation:-

1) Drawings, i.e Plans, elevation, sections etc.

2) Specifications.

3) Rates.

1) Rough Cost estimate :-

A Rough cost estimate is the approximation of the cost of a program, project, or operation. The Rough cost estimate is the product of the cost estimating process. The Rough  cost estimate has a single total value and may have identifiable component values.

2) Detailed cost 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

In detailed estimate :-

           1) Long and Short Wall Method
2) Centre Line Method
3) Partly centre line & partly cross wall method.
4) Graphical Method

1). Long & Short Wall Method:-

In this method, the wall along the length of room is considered to be long wall while the wall perpendicular to long wall is said to be short wall. To get the length 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 line length at each end. The length of long wall usually decreases from earth work to brick work in super structure while the short wall increases. These lengths are multiplied by breadth and depth to get quantities.

2) Centre Line Method:-

This method is suitable for walls of similar cross sections. Here the total centre line length is multiplied by breadth and depth of respective item to get the total quantity at a time. When cross walls or partitions or verandah walls join with main all, the centre line length gets reduced by half of breadth for each junction. Such junction or joints are studied carefully while calculating total centre line length. The estimates prepared by this method are most accurate and quick.

3)  Partly centre line & partly cross wall method:-

This method is adopted when external (i.e., around the building) wall iSOFT 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 issued to internal walls. This method suits for different thicknesses walls and different level of foundations. Because of this reason, all Engineering departments are practicing this method.

4) Graphical Method:-

Graphical method is mostly use for Cutting and Filling in Road and Cannel project’s.

In this method we use Grap paper  for finding cutting and filling.

Thanks!

Watch Video Tutorial

Click here to Watch Video Tutorial

(video is preparing) !!!