Current Measurement

[BOQ PREPARATION FOR SUBSTRUCTURE]

Abstract Building construction is a process of designing, estimating and erecting. Building is consists of substructure and superstructure. In a building each and every component is having a value, and it is approved by a standard method for evaluating its value. Therefore it is uniform for everyone who used it. The report first part will reveal about what is a bill of quantities and then it describes Use of The Standard Method of Measurement (SLS 573) for BOQ preparation. Finally the report concentrating on Practical problems faced by Quantity Surveyors when taking off quantities and preparing BOQs for substructure. Taking out the estimate of substructure, and certain issues arising when preparing BOQ and giving out the solutions for preparing satisfied bills of quantity for substructure.

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[BOQ PREPARATION FOR SUBSTRUCTURE]

Acknowledgement I present this report as “Current Measurement Practice In The Industry” comes under the “ Term Paper 3 ” The knowledge which I gained from the College of Quantity Surveying was very much useful for me in preparing this report. Information taken from the internet and several books relevant to the quantity surveying field, were also used for this report. First we very much thankful to Mrs B.A.K.S Perera, Miss Aparna Samaraweera,Miss Chathuri Gunarathna, Miss Mthusha Francis who are our lecturer and the staff of the College of Quantity Surveying for guiding me in this report. I would like to remind our colleagues of the College of Quantity Surveying who help and encourage us to complete this report. I would like to express my gratitude towards my friends for their kind co-operation and encouragement which help me in completion of this project and. I would like to express my special gratitude and thanks to my industry persons (National Housing Development Authority) for giving me such attention and time.

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[BOQ PREPARATION FOR SUBSTRUCTURE]

Table Of Content

Abstract.............................................................................................................................................i Acknowledgement...........................................................................................................................ii Table Of Content............................................................................................................................iii List Of Abbreviations.....................................................................................................................iv 1.0 Introduction................................................................................................................................1 2.0 Bills Of Quantities.....................................................................................................................2 2.1 Contents Of The Bill Of Quantities.......................................................................................3 2.2 Purposes Of Bills Of Quantities............................................................................................4 2.3 Production Of Bills Of Quantities.........................................................................................5 2.4 Divisions Of Bill Preparation.................................................................................................5 3.0 Substructure...............................................................................................................................6 4.0 Practical Problems Faced By Quantity Surveyor When Taking Off Quantities/ Preparing BOQ For Substructure....................................................................................................................7 5.0 Solutions Developed Based On Method Of Measurement Of Building Works (SLS 573).......8 5.1 Site preparation......................................................................................................................8 5.2 Site condition.........................................................................................................................8 5.3 Bulking...................................................................................................................................9 5.4 Removal Of Top Soil.............................................................................................................9 5.5 Excavation over site...............................................................................................................9 6.0

Other Problems...................................................................................................................11

6.1 Excavation and Disposal of Earth........................................................................................11 6.2 Measuring Of Breaking Out of Existing Rock Materials.....................................................11 6.3 Problem In measuring Ground Beams. Intersection of Beams............................................11 7.0.Conclusion and Recommendation...........................................................................................12 24.0 Reference...............................................................................................................................13 [Type text]

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[BOQ PREPARATION FOR SUBSTRUCTURE]

List Of Abbreviations

BOQ -

Bills of Quantities

SLS

Standard Method of Measurement

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1.0 Introduction The BOQ Preparation /Taking off quantities for Substructure is an important part of the Cost estimate, To Prevent over Costing/ minimize the cost, It Should be Accurate as possible. In this Particular Report Discuss about Problems which occurs when Preparation of Bill of quantities for Substructure. These Problems Raised As the result of Errors or conflict Situation of SLS 573 or Due to any other Practical Problems. The aim of this report is, 

Use of the Standard Method of Measurement (SLS 573) for BOQ preparation/ taking off quantities for substructure and find out Conflict Situations When Taking Off Quantities/ preparing BOQs for Substructure.



Practical problems faced by Quantity Surveyors when taking off quantities/ preparing BOQs for substructure.



Solutions developed for the problems encountered in preparing BOQs for substructure. (Related to SLS 573).

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Solutions developed for the problems encountered in preparing BOQs for substructure. (Other Solutions).

Current Measurement Practice In The Industry

2.0 Bills Of Quantities 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 item wised. It also (ideally) details the terms and conditions of the construction or repair contract and item wises all work to enable a contractor to price the work for which he or she is bidding. (Citing Wikipedia 2013, July 16) Bills of quantities are prepared by quantity surveyors and building estimators, and “Indeed the bill of quantities was the raison deter for the development of quantity surveying as a separate profession.” Bills of quantities are prepared by a “taking off” in which the cost of a building or other structure is estimated from measurements in the Architects, Structural Engineers, and other building consultant’s drawings. These are used to create a cost estimate such as in regard to the square area in meters of walls and roofs, the numbers of doors and windows, and systems as heating, plumbing and electrics. Similar types of work are then brought together under one item, a process known as "abstracting". Estimating books provide the relevant costs of the materials and labour costs of the operations or trades used in construction. As the rates for materials and labour change due to inflation, these books are frequently republished. The practice historically of estimating building costs in this way arose from non-contractual measurements, taken off drawings to assist tenderers in quoting lump sum prices. There are different styles of bills of quantities, mainly the Elemental BOQ and Trade Bills

Current Measurement Practice In The Industry

2.1 Contents Of The Bill Of Quantities The principle use for the bills of quantities is to obtain competitive tenders and for this purpose bills of quantities should be prepared to recognized Method of Measurement to standardize the bills. Bills of quantities, prepared in accordance with a Standard Method of Measurement, fully describe and accurately represent the works to be executed and this provides a uniform basis for competitive tendering. During the construction of the project the client and the contractor use the bills as the basis for financial management. Bills of Quantities may consist some or all of the following; Bill Nr.1 - Preliminaries Bill Nr.2 - Preambles Bill Nr.3 - Measured works, (a) Carcass

i. Foundations (substructure) ii. Frame (columns and beams) iii. External and internal walls iv. Partitions v. Floors vi. Roofs

Current Measurement Practice In The Industry

(b) Finishing

i. External & internal finishing ii. Windows iii. Doors including opening without joinery iv. Fixtures & sundries v. Stairs & lifts vi. Plumbing & Engineering services

(c) External works

i. Drainage ii. Roads, Paths, Site layouts, Outbuilding etc..

(d) Spot items

i. Alteration and repair items of a building

Bill Nr.4 – Provisional quantities Bill Nr.5 – Prime cost & Provisional sums Bill Nr.6 – Contingency sums Bill Nr.7 – General summary

2.2 Purposes Of Bills Of Quantities The bills of quantities are in use to the construction team for different purposes at different stages and it is used in different ways. They are as follows; a. Tendering b. Valuation of interim certificates

Current Measurement Practice In The Industry

c. Valuation of variations d. Ordering of materials e. Cost analysis for future use f. Reference during the construction – quality and cost g. Construction planning and monitoring h. Sub – contractor quotation i. Final accounts

2.3 Production Of Bills Of Quantities There are several techniques of preparing Bills of Quantities. The most important techniques in current use are as follows; a. Traditional Method. This system provides the “taker off” with a logical system of measurement designed to promote accurate and efficient taking off. This method is also known as the Group system or London Method.

b. Billing Direct. This method involves “taking off” by trades, in order of billing, without the necessity for an abstract and transfers the measured items from the dimension sheets to the bill direct. This method is also known as Trade –by- Trade system or Northern Method.

Current Measurement Practice In The Industry

2.4 Divisions Of Bill Preparation The traditional method of preparation of bills of quantities can be broken down into two main processes. a. Taking off. This involves the measurement of dimensions, scaled or read from the drawings and entered in a recognised form of specially ruled paper called “Dimension paper” and the composition of clear and concise description sufficiently detailed to allow the accurate pricing of the works. b. Working up. When the taking off is complete squaring the dimensions and transferring the resultant lengths, areas and volumes to the abstract. Then squared dimensions are arranged in convenient order for billing and reduced to the recognised units of measurement. Also all the description and quantities are put in a logical order and then the Bill is typed.

3.0 Substructure

The building can be dividing into two main categories as Substructure and Superstructure. Bellow ground structure known as substructure and it is the base of the building. Below ground is invisible, but engineer assume below ground condition according to soil report. Then he decides what kind of foundation use for the building and he prepared detail drawing. Therefore the main responsibility of Substructure is goes under a professional Engineer.

Current Measurement Practice In The Industry

Upper ground structure known as superstructure and it is the Client and Architect imagining output in the building. In Superstructure the main responsibility is goes to the Architect, as client idea visuals in superstructure. The quantity surveyors job applies to combine the two professional ideas into form of estimate. Therefore taking out quantities from the sub structure and superstructure is varies due to its condition, as superstructure is upper ground construction and it can be controlled as it is visible. But the natural condition of the below ground is non predictable, and therefore additional responsibilities is goes to the quantity surveyor to prepare the estimate to be satisfied with the additional cost might rising due to the above reason.

4.0 Practical Problems Faced By Quantity Surveyor When Taking Off Quantities/ Preparing BOQ For Substructure

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Site preparation the

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- Clearing of site vegetation is measured as a superficial item and if

area to be cleared is not given,

Site condition

- Before commencing the taking off for foundation works,

drawings should be inspected to ascertain the existing ground levels and to determine the average depths of excavations. If the levels are not given, 

Bulking

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Removal of top soil - When new buildings are to be constructed on natural ground,

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Excavation over site - When a site is sloping,

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Levels

- Commencing level,

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Pit excavation

- Pit excavation is measured,

- Dimensions for volumes of excavation,

Current Measurement Practice In The Industry

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Trench excavation

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Basement excavation- Basement excavation is measured,

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Earthwork support - Actually required or not,

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Disposal of water

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Surface treatments - The bottom of excavations should be leveled and compacted

- The measurement of trench excavation,

- How to measured,

before commencing concrete or stonework foundation works and is measured as a superficial item. Before filling to makeup levels,

5.0 Solutions Developed Based On Method Of Measurement Of Building Works (SLS 573).

5.1 Site preparation Clearing of site vegetation is measured as a superficial item and if the area to be cleared is not given, the accepted area for clearing is 3.0 m away from all external faces of extreme external walls. The clearing of site vegetation includes; bushes, shrub, under growth hedges and trees and stumps not exceeding 500 mm girth is measured separately. The tree girths area measured at a height of 1.0 m above ground level. 5.2 Site condition Before commencing the taking off for foundation works, drawings should be inspected to ascertain the existing ground levels and to determine the average depths of excavations. If the levels are not given, the quantity surveyor is to visit the site to take a grid of the levels of the site. In addition, he should ascertain the nature and location of existing buildings, details for preliminary items and for the measurement of excavation works. Other items to be noted are;

Current Measurement Practice In The Industry

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Site vegetation to be cleared,

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Existence of topsoil or turf to be preserved,

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Paving or existing structures to be demolished,

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Nature of the ground,

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Ground water level.

Site visit can be delayed until the general taking off is done, as notes can be made during the taking off, of what must be looked at on the site. If the proposed works consists of mainly of alterations, an early visit to the site is necessary, as most of the measurements have to be done at site. 5.3 Bulking Dimensions for volumes of excavation, disposal and filling shall be taken net as they are in the ground. No account is taken for the soil increase in bulk after excavation in the bills of quantities, but the estimator has to make due allowance in the unit rates of the item. 5.4 Removal Of Top Soil When new buildings are to be constructed on natural ground, it is required to measure a separate superficial item for removing vegetable or topsoil, where it is to be preserved. The measurements are taken over the area of the whole building including the projection of the foundations beyond the external faces of external walls. A separate cubic item shall be measured for the disposal of the topsoil on site spoil heaps giving the location excavation for trenches pits, basements etc., shall than be measured from the underside of the topsoil excavation, which is called the commencing level. 5.5 Excavation over site When a site is sloping, a superficial item is measured where the average depth is less than 300mm or a cubic measurement is taken where the depth exceeds 300mm stating the maximum Current Measurement Practice In The Industry

depth of the excavating to reduced levels, by cutting part of the site and filling the other part with the excavated materials making the site leveled. The excavation to reduced levels should be measured before any trench or pit digging, as it brings the surface to the “reduced or formation level”, from which the trench or pit digging is measured.

5.6 Levels The following three types of levels should be known before foundations are measured, (a) Bottom of foundation, (b) Existing ground level, and (c) Floor level. (a) and (b) above are required to measure pit or trench excavation and (a) and (c) above are required to calculate the correct heights of column shafts, brickwork or other walling. If the natural ground level varies, the levels have to be averaged either for the whole building or for sections of it. The measurement of trench excavation is very easy, if the floor levels and the bottom of the foundation levels are constant. In some buildings, both bottom of foundation and the floor level may vary in different parts making the measurement of foundations very complicated. Therefor it is useful to mark the existing ground levels on the plan. (a) Pit excavation

- Pit excavation is measured as a cubic item and a separate cubic item of

disposal should be measured. The SMM requires stating the commencing level of excavation, and the pits, whose area is not exceeding 1.0 m2 on plan, to be measured separately. (b)Trench excavation

- The measurement of trench excavation is divided in to two

sections;

Current Measurement Practice In The Industry

(a) Trenches, width exceeding 300 mm, and (b) Trenches, width exceeding 300 mm. Trench excavation, width exceeding 300 mm, shall be measured as a cubic item and a separate cubic item of disposal is to be measured. Trench excavation, width not exceeding 300 mm shall be measured as a linear item stating the width and the depth. The commencing level of excavation should also be stated. Internal walls to be collected up in groups according to the thickness of the walls, width of the foundations and the average depths of excavations. Mean lengths of internal walls are taken and adjustments are made in the length for overlaps (called “T” junctions), where internal walls abuts external walls by deducting half the width of the foundation for each “T” junction, from the internal wall lengths. A similar adjustment must be made, where internal walls intersect. a) Disposal of water

- A separate item for disposal of surface and ground water

shall be measured as an item. b) Surface treatments - The bottom of excavations should be leveled and compacted before commencing concrete or stonework foundation works and is measured as a superficial item. Before filling to makeup levels, a separate superficial item shall be measured as leveling and compacting ground.

6.0Other Problems 6.1 Excavation and Disposal of Earth. When Excavating Soil the SLS 573 Consider the Bulk Excavated = Bulk Disposal No allowance for increasing of volumes

6.2 Measuring Of Breaking Out of Existing Rock Materials. (Section D.4.1) It is Difficult Measure Breaking out existing rock materials in volumes (m3) Current Measurement Practice In The Industry

6.3 Problem In measuring Ground Beams. Intersection of Beams. According to SLS 573 in Concrete Work Measurement rule M1, Concrete measured in Net Volume, No Deductions are done for intersection of volumes. But practically if ignored intersections the qty; increase highly and cost of BOQ increases for unnecessary volumes.

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7.0.Conclusion and Recommendation. This section takes account of the standards and explains about the standards relating to present situation. It creates arguments and questioning if the SLS 573 standards Suitable for current construction industry? And according to the answer tries to find out what are the Problems caused these situations, and what are the Solutions affecting to Prevent Conflict Situations, negligence of the standard methods of measurements. The quantity of material in a project can be accurately determined from the drawings. The estimator must review each sheet of the drawings, calculate the quantity of material and record the amount and unit of measure. Each estimator must develop a system of quantity takeoff that ensures that a quantity is not omitted or calculated twice. A well-organized check-list of work will help reduce the chances of omitting an item. The estimator must, also, add an appropriate percentage for waste for those items where waste is likely to occur during construction. The material quantity takeoff is extremely important for cost estimating because it often establishes the quantity and unit of measure for the costs of labor and contractor’s equipment. So, To Produce an Accurate Cost Estimate It is necessary to Change some of the Phrases, Regulations and Rules of SLS 573 as Suitable to the Practical Situations. Though these revisions Current Measurement Practice In The Industry

of SLS 573 is not done, Estimators can use their own Rules and Regulations for Conflict Situations, But it would not give Uniform Comparable output due to these errors.

24.0 Reference I. II. III.

Cost Estimating 21 Dr. EmadElbeltagi ICTAD. (1999).Standard Method of Measurement of Building works.SLS 573. SrinathPerera, GayaniKarunasena&ThileshFonseka, (2003) Built-Environment-Sri Lanka -Vol. 03,A web-based user guide for Sri Lanka Standards 573: Standard Method of Measurement of Building Works.

Current Measurement Practice In The Industry