Willis's Elements of Quantity Surveying

Sandra Lee

• Publisher: Wiley-Blackwell
• Year: 2020
• ISBN:
  9781119633198
• Edition: 13
• Topic: Technology & Engineering
• Subtopic: Technology & Engineering Research & Skills
• Index: Technology & Engineering

Willis's Elements of Quantity Surveying has become a standard text in the teaching of building measurement – a core part of the degree curriculum for quantity surveyors. The book will be fully updated to follow the guidance given by RICS NRM 1 & 2. As in previous editions the focus remains a logical approach the detailed measurement of building elements and copious use of examples to guide the student. The text has been fully revised in line with the NRM guidance and includes many new and revised examples illustrating the use of NRM. The hallmarks of previous editions – clarity and practicality – are maintained, while ensuring the book is fully up to date, providing the student of quantity surveying with a first class introduction to the measurement of building elements.

Chapter 1
Introduction

The modern quantity surveyor

The training and knowledge of the quantity surveyor have enabled the role of the profession to evolve over time into new areas, and the services provided by the modern quantity surveyor now cover all aspects of procurement, contractual, and project cost management. This holds true whether the quantity surveyor works as a consultant or is employed by a contractor or subcontractor. Whilst the importance of this expanded role cannot be emphasised enough, success in carrying it out stems from the traditional ability of the quantity surveyor to measure and value. It is on the aspect of measurement that this book concentrates.

The need for measurement

There is a need for measurement of a proposed construction project at various stages from the feasibility stage through to the final account. This could be in order to establish a budget price, give a pre‐tender estimate, produce contract documents for pricing, provide a contract tender sum, or evaluate the amount to be paid to a contractor. There are many construction or project management activities that require some form of measurement so that appropriate rates can be applied to the quantities and a price or cost established.

The measurement explained in this book is primarily for the production of a bill of quantities as part of the traditional procurement approach to construction. Other procurement approaches move the need for detailed measurement to later stages of the project cycle and away from activity undertaken by the client's team to that of the contractor's team.

The need for rules

The need for rules to be followed when undertaking any measurement becomes clear when costs for past projects are analysed and elemental rates or unit rates are calculated and then applied to the quantities for a proposed project. For greater accuracy in pricing, it is important to be able to rely consistently on what is included in an element or unit, and this helps build a more reliable cost database.

Following the Royal Institute of British Architects (RIBA) 2013 Work Stages, the measurement undertaken at Stage 1 – ‘Preparation’ – needs to be of basic areas or functional units, and the guidelines of the Royal Institute of Chartered Surveyors (RICS) Code of Measuring Practice are commonly followed. This enables comparisons to be made between different schemes and options when assessing the feasibility of a project. When preparing a cost plan, the need to include the same items in each element is important so that costs for that element can be accurately applied. In May 2009, the RICS published the first of its new set of rules for measurement dealing with the order of cost estimates and elemental cost planning. The RIBA work stages and the New Rules of Measurement (NRM) are explained a little further in Chapter 2.

The same need for rules applies when measuring for bills of quantities. If a document is to be used for tender purposes and included in a contract, then the contractor needs to know the basis of the measurement and what is included or excluded from an item to be priced. Historically, standard methods of measurement have been used to provide these rules and are available in various forms worldwide. The RICS NRM – detailed measurement for building works (NRM2) are part of the RICS ‘black book’ guidance for accepted practice in the UK. At post‐contract stages, when measuring for variations or additional works, it is important that the rules used in the contract document (if applicable) are followed to minimise disputes.

Establishing the approach

The approach to take for any measurement is to decide its purpose and the level of design detail available, enabling the adoption of the most appropriate rules and procedures.

Having an ability to read and understand the rules for measurement for bills of quantities should enable the measurer to appreciate the requirements of different rules and approaches.

Method of study

Before you start to work through the chapters on each element it is advised to study Chapters 1–7 in order to grasp the basic principles thoroughly. You should understand the form in which dimensions are usually written, irrespective of whether a computer system will eventually be used to record dimensions in practice.

Knowledge of elementary building construction and simple mensuration and trigonometry is assumed; where knowledge is weak in these subjects, further study is recommended before proceeding further with measurement.

Chapter 5 explains some of the alternative systems that are used in practice, and Chapter 6 explains how girths and centre lines are calculated.

Chapter 7 contains notes on general procedure rules for taking‐off which should be read before attempting to study actual examples of measurement, and to which subsequent referral may also be useful.

Chapters 8–18 represent the sections into which the taking‐off of a small building might be divided, and these should be worked through one at a time. The principal applicable clauses of NRM2 are referred to in each chapter and should be studied concurrently. After the chapter has been read, the examples should be worked through. It should be possible to follow every measurement by reference to the drawing. It may therefore be appropriate for you to copy or print off the drawings so that they can be read alongside the dimensions.

The examples of taking‐off in this book are small isolated parts of what could be the dimensions of a complete building and are not a connected series. When they have been mastered in their isolation, it will be much easier to see how they might be expanded and fitted together to compile a bill of quantities for a complete building.

Chapters 19 and 20 deal with preliminaries and bill preparation, which are more logically dealt with after taking‐off, as this is often a separate process.

Examples

The measurement examples are included to illustrate the measurement of individual elements of a small building. They assume that full specification clauses would be set out in preambles to the bill and are not included here (see Chapter 20).

The dimensions that are set down in the dimension column when taking‐off are given to the nearest two decimal places of a metre. Side casts (or waste calculations, as they are sometimes called) are used to calculate these dimensions, and are given in millimetres to ensure accuracy.

The examples in the chapters are presented in a traditional dimension format, this being considered the best system for a textbook and what the candidate will usually be faced with in the examination room. Abbreviations have been used for deductions where a description sufficient to recognise an item clearly is all that is required. The abbreviations used in the descriptions are listed in the ‘Abbreviations’ section at the beginning of this book.

There is a companion website for this book where some of the examples are included as audio presentations to provide further explanation if required.

Chapter 2
Detailed Measurement

Method of analysing cost

It is evident that if a building is divided up into its constituent parts, and the cost of each part can be estimated, an estimate can be compiled for the whole work. It was found in practice that by making a ‘schedule’ setting out the quantity of each item of work for a project, the labour and material requirements for these could be more read...