Hello everyone, Here are some principles in taking off quantities of the construction field. Taking off quantities is one of the job roles of a quantity surveyor. In this process normally we use taking off sheets also called "TDS sheet" to purposes of taking off quantities.

In construction projects, there are several measure work (such as excavation work, rubble work, concrete work, etc), we have to carry out the take of quantity process to prepare the bill of quantities.

We also know as a quantity surveyor, prepare a bill of quantities is the final output of taking of quantity process.

As a quantity surveyor or other relevant profession, you should follow these principles during your taking off quantity process.

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Principles of Taking off Quantities In

Taking off Sheet (T.D.S)

Timesing column

Quantity surveyors use the term ‘timesing’ rather than ‘multiplication’ to refer to the number of times a particular item occurs in the course of measurement. The timesing factor is entered in the timesing column and is registered by a backslash mark across the border between the timesing and dimension columns.

Squaring the Dimensions

The squaring column is used to calculate the quantities of work and represents the products of the timesing and dimension columns. The squaring process figures out the quantities of work by multiplying the dimensions by the timesing factor.

There are a number of conventions to note:

• In situations where there are multiple dimensions for enumerated items or linear dimensions that are not timesed, these may be totaled and the result entered in the squaring column to the right of the final number/dimension. There would be no need to insert each dimension in the squaring column.

• Where enumerated items or dimensions are timesed each calculation should be entered separately in the squaring column.

• Enumerated items are entered or totaled as whole numbers in the squaring column.

• Squared dimensions are entered in the squaring column to two places of decimals and are totaled alongside or below the final dimension entry. Note that there is no underlining in the squaring column until the totaling process is carried out. Totaling is usually signified by double underlining.

• Totals are usually rounded off to the nearest full unit and transferred to the right-hand side of the description column immediately below the description. This accords with standard practice

Use of the Description Column

The group method groups related work items with common dimensions, such as block work plaster and paint, and measures them together simultaneously using brackets and a technique called ‘anding on’. Measurements and adjustments relating to the particular work items are gathered from the various sections of the takeoff and aggregated in an abstract to produce the final quantities prior to final billing.

Work descriptions in the ‘group’ approach are contained within the description column and are heavily abbreviated and copied using the word ‘ditto’ to save time and space. This allows a number of descriptions to be written in the description column. The full descriptions of the work items are only produced at the final billing stage.

Numbering and Titles of Dimension Sheets

Each dimension sheet should be suitably headed with the job and page reference at the top of each sheet. A dated and initial cover sheet identifying the job, stage, element and total number of pages used in the take-off is good practice. This cover sheet should also contain a list of drawings used for the take-off. The take-off should be suitably fastened to prevent loss of sheets.

Golden rule in Measurement

The golden rule in quantity surveying is to enter the measurement – length, width and depth/ height, order

A constant order of entering dimensions should be maintained throughout in accordance with General rules 4.1, that is

Work shall be measured as net as fixed in position and each measurement shall be taken to the nearest two places of decimals. (When taking two decimals if there is 5 it is not accepted for next point)

Ex. -

9.534 = 9.53
8.267 = 8.27
4.555 = 4.55

Work shall be measured as net as fixed in position and each measurement shall be taken to the nearest 10 mm. (5 mm and over shall be regarded as 10 mm, and less than 5 mm shall be disregarded).

Volumes

Excavation, earthwork, and concrete work are typically measured by volume. These items contain three dimensions which ideally are arranged in the order of length by width by depth. Again, the sets of three dimensions are identified by the horizontal under the third dimension of the set.

Areas

Items such as walls, roof coverings, floor boarding, and most finishes are measured by area. These are sometimes referred to as superficial measurements. The description usually states the thickness of the item of the work. The measurements comprise two dimensions; a length and width when the item is on a plan, or a length and a height where it is vertical. Dimensions are arranged in pairs in the dimension column with the horizontal line appearing under the second dimension.

Lengths

Linear measurements (lengths) are taken for items such as damp proof courses, details such as bands and capping on brickwork and first fix timbers, runs of pipe, etc. Linear measurements usually state the cross-section size of the item in the description.

Number / Enumeration

Many items in building work are counted, for example, precast concrete lintels and sills, prefabricated roof trusses, joinery items such as doors, and windows, electrical and mechanical fittings such as lights, radiators, and pumps, sanitary fittings such as baths and so on. Where items are counted they are entered as whole numbers in the dimension column with a line drawn horizontally across the dimension column below each entry.

Item

This is an item of work without a measured quantity, for example disposing of surface water in excavation work, labors on brickwork, testing the drainage system, etc.

The dotting on system

This technique is not encountered frequently in practice, but there may be occasions where a further item or items have been discovered after similar work has already been measured. The process is signified by inserting a conspicuous large ‘dot’ behind and above the timesing factor while entering the number of the additional items.

Bracketing

Where more than one set of dimensions related to the same description, the dimensions should be suitably bracketed so that this shall be made clear.

Brackets and Anding on

Alterations to Dimensions

It is sometimes necessary to substitute amended dimensions in place of those, which have already been entered on the dimension sheet. Do not alter the original figures. The better procedure is to write NIL in the squaring column beside the incorrect dimensions and rewrite the new dimensions immediately above or below depending on the space available.