ADVANCED CONSTRUCTION TECHNOLOGY

by HAMMAM Mohammed
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PREFACE TO THIRD EDITION

Roy Chudley’s Construction Technology was first published in four volumes, between 1973 and 1977. The material has since been continuously updated through

numerous reprints and full second editions in 1987. The books have gained a worldwide readership, and their success – and their impact on construction education – is a tribute to Roy Chudley’s experience in further and higher education and his talents as a skilled technologist, illustrator and writer.

As a former colleague, it has been a privilege to once again work with Roy, on this occasion revising his original work, and compiling the material into two books:

Construction Technology and Advanced Construction Technology. The content forms a thorough study for all students of building, construction management, architecture, surveying and the many other related disciplines within the diverse construction profession.

The original presentation of comprehensive text matched by extensive illustration is retained. Changes in legislation, such as the Building and Construction Regulations, have been fully incorporated into the text; however, as much of the original work as possible has been purposely retained as it contains many relevant examples of existing construction. Additional material discusses the new developments and concepts of contemporary practice.

The two new volumes are complementary, as many of the topics introduced in Construction Technology are further developed here. Together the books provide essential reading for all students aspiring to management, technologist and professional qualifications. They should be read alongside the current local building regulations and national standards, and where possible supplemented by direct experience in the workplace.

PREFACE TO FOURTH EDITION

Since the previous edition, reprint opportunities have permitted some amendments.
These have included new procedures, relative to legislative and practice changes.

This revised edition develops these further, with greater attention to information and detail. It also incorporates more recent issues, especially aspects of the Building Regulations that require buildings to be designed and constructed to higher energyefficient standards. The responsibilities on building designers and owners with

regard to human rights are considered in a new chapter outlining the facilities required for the convenience of the less able using buildings other than dwellings.

Notwithstanding contemporary requirements, the book’s established construction principles are retained. These provide a useful reference to existing building stock, and, where appropriate, modifications are included to illustrate ongoing change.

The content represents the basic elements of construction practice. The book is neither extensive nor prescriptive, as there is insufficient space in any book to include every possible means for constructing commercial and industrial buildings.

However, the content is generally representative, and the reader is encouraged to develop their knowledge through experiential learning, observation in the workplace, and reading manufacturer’s literature and technical articles in
professional journals. Reference sources for supplementary reading are provided throughout.

In conjunction with this edition’s companion volume, Construction Technology, the reader should gain an appreciation of the subject material to support progression through any technical, academic or professional qualification study programme that includes construction as core or supplementary modules.

ACKNOWLEDGEMENTS

This book originated in the 1970s as part of a four-volume series written by Roy Chudley. As a result of its popularity, numerous reprints and a new edition followed. In 1998 the series was rewritten by Roger Greeno as two separate volumes: the initial two volumes formed the basis for the companion title, Construction Technology, and the remainder, Advanced Construction Technology.

The book’s endurance is a tribute to Roy’s initial work in representing construction practice with comprehensive illustrative guidance and supporting text. I am particularly grateful to the founding author for allowing me the opportunity to continue this work and to emulate his unique presentation. I am also grateful to the late Colin Bassett as general editor. It was his initiative and enthusiasm that encouraged me to pursue this work.

No book can succeed without a good publisher, and Pearson Education have fulfilled that role with their supportive editorial and production team. In particular, Pauline Gillett has been a constant source of direction and help throughout the preparation of the manuscript.


We are grateful to the Building Research Establishment and The Stationery Office Ltd for permission to reproduce material from the BRE Digests and various Acts, Regulations and Statutory Instruments.


Extracts from British Standards are reproduced with the permission of BSI. Complete copies can be obtained by post from BSI Customer Services, 389 Chiswick High Road, London W4 4AL

INTRODUCTION

Advanced Construction Technology is a development of the relatively elementary construction detailed in the associated volume, Construction Technology. This volume augments the associated volume with further topics relating to domestic buildings and lightweight-framed structures, in addition to concentrating primarily on complex and specialised forms of construction.

It is designed to supplement a student’s lecture notes, projects and research assignments as well as to provide a valuable professional reference. It also complements the associated subjects of science, mathematics, materials technology, design procedures, structural analysis, structural design, services, quantity surveying, facilities management and management studies, and is therefore appropriate for most undergraduate and higher-level construction study programmes.

The format adopted follows that of Construction Technology, providing concise notes and generous illustrations to elaborate on the text content. The reader should appreciate that the illustrations are used to emphasise a point of theory and must not be accepted as the only solution. A study of working drawings and details from building appraisals given in the various construction journals will add to background knowledge and comprehension of construction technology.

No textbook or work of reference is ever complete. Therefore readers are recommended to seek out all sources of reference on any particular topic of study, to maximise information and to gain a thorough comprehension of the subject.

Construction technology is not purely academic; lectures and textbooks can only provide the necessary theoretical background to the building processes of design and site application. Practical experience and monitoring of work in progress are essential components of any study programme involving the subject of construction technology.

SITE LAYOUT

The construction of a building can be considered as production with a temporary factory, the building site being the ‘factory’ in which the building contractor will make the product. To enable this activity to take place the builder requires operatives, materials and plant, all of which have to be carefully controlled so that the operatives have the right machines in the most advantageous position, the materials stored so that they are readily available and not interfering with the general site circulation, and adequate storage space and site accommodation.

There is no standard size ratio between the free site space required to construct a building and the total size of the site on which the building is to be erected:

therefore each site must be considered as a separate problem in terms of allocating space for operatives, materials and plant. To obtain maximum efficiency there is an optimum way of laying out the site and also a correct amount of expenditure to support the proposed site layout. Any planned layout should be reviewed periodically and adjusted to suit the changing needs of the site activities. If this aspect of building construction is carefully considered, planned and controlled, it will be reflected in the progress and profitability of the contract.

Before any initial planning of the site layout can take place certain preliminary work must be carried out, preferably at the pre-tender stage. The decision to tender will usually be taken by the managing director or, for small works, by the senior estimator up to a contract value laid down by the managing director. With given designs and specifications the best opportunity for the contractor to prepare a competitive and economic tender is in the programming and planning of the construction activities. A thorough study of the bill of quantities will give an indication of the amount and quality of the materials required and also of the various labour resources needed to carry out the contract. A similar study of the drawings, together with the bill of quantities and the specification, will enable the builder to make a preliminary assessment of the size and complexity of the contract, the plant required, and the amount of money that can reasonably be expended on 6 Advanced Construction Technology labour-saving items such as concrete mixing and placing alternatives, handling and transporting equipment and off-site fabrication of such items as formwork and
reinforcement.

Before the estimator can make a start on calculating unit rates a site investigation should be carried out, preferably by the site manager, who will supervise the contract should the tender be successful. The manager’s report should include the following information:

  • Access to site On- and off-site access, road and rail facilities, distances involved, rights of way restrictions, local authority or police restrictions and bridge weight or height limitations on approach routes.
  • Services Available power and water supplies, together with rates of payment, nuisance or value of services already on site, diversions required, and the time element involved in carrying out any necessary diversions together with cost implications.
  • Layout General site conditions such as nature of soil, height of water table, flooding risks, tidal waters, neighbouring properties, preservation orders, trees, demolition problems and special insurance considerations.
  • Staff Travel distances, availability of local trade contractors, specialist contractors, local rates of pay and facilities to be provided, e.g. site accommodation, catering, health and safety equipment.
  • Security Local vandalism and pilfering record, security contractors’ facilities, need for night security, fencing and hoarding requirements.

With the knowledge and data gained from contract documents, site investigations, and any information gained from the police and local authority sources the following pre-tender work can now be carried out:

  • Pre-tender programme Usually in a barchart form showing the proposed time allowances for the major activities.
  • Pre-tender health and safety plan This is prepared by the project coordinator (usually the architect) to enable tendering contractors to consider the practical and cost implications and adequacy of their resources with regard to assessment of risk in safety issues and provision of welfare requirements.
  • Cost implications Several programmes for comparison should be made to establish possible break-even points giving an indication of required bank loan, possible cash inflow and anticipated profit.
  • Plant schedule This can be prepared in the form of a barchart and method statements showing requirements and utilisation, which will help in deciding how much site maintenance, equipment and space for plant accommodation will be needed on site. Consideration of whether to purchase or hire plant can be ascertained from these data, although this is only likely to affect smaller items such as specialised tools, as few builders could justify owning large items of plant. However, a balance of buying and hiring will have to be established at this stage.
  • Materials schedule Basic data can be obtained from the bill of quantities. The buyer’s knowledge of the prevailing market conditions and future trends will enable usage and delivery periods and the amount of site space and/or accommodation required to be predicted.
  • Labour summary Basic data obtained from the bill of quantities, site investigation report and pre-tender barchart programme to establish number of subcontract trades required. Also the quantity and type of site personnel accommodation required.
  • Site organisation structure This is a ‘family tree’ chart showing the relationships and interrelationships between the various members of the site team, and is normally required only on large sites where the areas of responsibility and accountability must be clearly defined.
  • Site layout Site space allocation for materials storage, working areas, units of accommodation, plant positions and general circulation areas. Access and egress for deliveries and emergency services.
  • Protection Protection of adjacent buildings, structures (including trees) with preservation orders and provision of fencing/hoarding to prevent trespass and to protect people in the vicinity. Check adequacy of insurances.

PLANNING SITE LAYOUTS

When planning site layouts the following must be taken into account:

  • site activities;
  • efficiency;
  • movement;
  • control;
  • facilities for health, safety and welfare provision;
  • accommodation for staff and storage of materials.

SITE ACTIVITIES

The time needed for carrying out the principal activities can be estimated from the data obtained previously for preparing the material and labour requirements. With repetitive activities estimates will be required to determine the most economical balance of units that will allow simultaneous construction processes; this in turn will help to establish staff numbers, work areas and material storage requirements.

A similar argument can be presented for overlapping activities. If a particular process presents a choice in the way the result can be achieved the alternatives must be considered: for example, the rate of placing concrete will be determined by the output of the mixer and the speed of transporting the mix to the appropriate position. Alternatives that can be considered are:

  • more than one mixer;
  • regulated supply of ready-mixed concrete;
  • on large contracts, pumping the concrete to the placing position.

All alternative methods for any activity will give different requirements for staff numbers, material storage, access facilities and possibly plant types and numbers.

EFFICIENCY

To achieve maximum efficiency the site layout must aim at maintaining the desired output of the planned activities throughout the working day, and this will depend largely upon the following factors:

  • Avoidance, as far as practicable, of double handling of materials.
  • Proper storekeeping arrangements to ensure that the materials are of the correct type, in the correct quantity, and available when required.
  • Walking distances kept to a minimum to reduce the non-productive time spent in covering the distances between working, rest and storage areas without interrupting the general circulation pattern.
  • Avoidance of loss by the elements by providing adequate protection for unfixed materials on site, thereby preventing time loss and cost of replacing damaged materials.
  • Avoidance of loss by theft and vandalism by providing security arrangements in keeping with the value of the materials being protected and by making the task
  • difficult for the would-be thief or vandal by having adequate hoardings and fences. Also to be avoided is the loss of materials due to pilfering by site staff, who may consider this to be a perquisite of the industry. Such losses can be reduced by having an adequate system of stores’ requisition and material checking procedures. Engaging specialist subcontractors on a ‘supply and fit’ basis may reduce the main contractor’s concern.
  • Minimising on-site traffic congestion by planning delivery arrivals, having adequate parking facilities for site staff cars and mobile machinery when not in use, and by having sufficient turning circle room for the types of delivery vehicle likely to enter the site.

MOVEMENT

Apart from the circulation problems mentioned above, the biggest problem is one of access. Vehicles delivering materials to the site should be able to do so without difficulty or delay. Many of the contractors’ vehicles will be lightweight and will therefore present few or no problems, but the weight and length of suppliers’ vehicles should be taken into account. For example, a fully laden ready-mix concrete lorry can weigh 20 tonnes, and lorries used for delivering structural steel can be 18.000 metres long, weigh up to 40 tonnes and require a large turning circle.

If it is anticipated that heavy vehicles will be operating on site it will be necessary to consider the road surface required. If the roads and paved areas are part of the contract and will have adequate strength for the weight of the anticipated vehicles it may be advantageous to lay the roads at a very early stage in the contract, but if the specification for the roads is for light traffic it would be advisable to lay only the base hoggin or hardcore layer at the initial stages because of the risk of damage to the completed roads by the heavy vehicles. As an alternative it may be considered a better policy to provide only temporary roadways composed of railway sleepers, metal tracks or mats until a later stage in the contract, especially if such roads will only be required for a short period. See also the Construction (Health, Safety and Welfare) Regulations 15 to 17.

CONTROL

This is concerned mainly with the overall supervision of the contract, including staff, materials, and the movement of both around the site. This control should form the hub of the activities, which logically develops into areas or zones of
control radiating from this hub or centre. Which zone is selected for storage, accommodation or specific activities is a matter of conjecture and the conditions prevailing on a particular site, but as a rule the final layout will be one of compromise, with storage and accommodation areas generally receiving priority.

FACILITIES

These must be planned for each individual site, but certain factors will be common to all sites – not least the implications of the Construction (Health, Safety and Welfare) Regulations 1996, the Work at Height Regulations 2005 and the Health and Safety at Work etc. Act 1974. The main contractor is obliged to provide a safe, healthy place of work, and safe systems of work, plant and equipment that are not a risk to health. Equipment for the conduct of work must be provided with adequate information for its safe use and, where appropriate, training in its application. Both regulations are wide ranging and set goals or objectives relating to risk assessment to ensure reasonably practicable steps are taken to ensure safety provision. Prescriptive requirements for such provisions as scaffold guard rail heights and platform widths are scheduled in the Work at Height Regulations.

The principal considerations under the Construction (Health, Safety and Welfare) Regulations can be summarised as follows:

  • Regulation 5: Safe places of work. This requires that people are provided with properly maintained safe surroundings in which to work, along with safe means of accessing and leaving that place of work. It is an overall requirement for reasonable precautions to be taken, with the perceived and varying risk associated with every place of work. Sufficient and suitable working space should be provided with regard to the activity being undertaken.
  • Regulation 7: Precautions against falling through fragile material. This applies mainly to work at heights in excess of 2 m, although potential for falls from any height must be assessed. Requirements for sufficient and adequate means of guarding persons from fragile material must be in place, with a prominence of warning notices displayed in the vicinity (see also Work at Height Regulations).
  • Regulation 8: Falling objects. This requires sufficient and suitable means for preventing injury to persons from falling objects. Provisions may include guard rails, toe boards and protective sheeting to scaffold systems. No material to be tipped or thrown from height (see rubble chutes, Chapter 5.2). Material to be stored or stacked in a stable manner to prevent collapse or unintentional movement.
  • Regulations 9 to 11: Work on structures. A large amount of work associated with the construction of buildings is essentially temporary. Therefore potential for structural collapse, e.g. inadequately supported formwork, is very real and must be recognised and assessed by a competent person. The necessary precautions must be taken to prevent danger. Demolition and dismantling are also high-risk areas, justifying thorough planning and risk analysis before and as work proceeds.
  • Regulations 12 and 13: Excavation, cofferdams and caissons. Substructural work has an inherent danger of collapse. Suitable provision to prevent collapse of trenches etc. must be designed and installed by competent specialists. Awareness of water-table levels and possible variations, e.g. seasonal and tidal, is essential, as is location of underground cables and other services that could be a danger.
  • Regulation 14: Prevention of drowning. This is not applicable to all sites, but if there is a danger from water or other liquids in any quantity then every practical means possible must be taken to prevent people falling into it. Personal protective and rescue equipment must be available, maintained in good order, and water transport must be provided under the control of a competent person.
  • Regulations 15 to 17: Traffic routes, vehicles, doors and gates. These make provision for segregation of vehicles and pedestrians, with definition of routes.
  • The regulations require adequate construction and maintenance of temporary traffic routes, control of unintended traffic movement, warnings (audible or otherwise) of vehicle movements, prohibition of misuse of vehicles, and safeguards for people using powered doors and guards such as that on hoist facilities.
  • Regulations 18 to 21: Prevention and control of emergencies. These make provision for emergency routes, means of escape, evacuation procedures, adequate signing, firefighting equipment, emergency lighting and associated training for dealing with emergencies.
  • Regulation 22: Welfare facilities. Minimum requirements apply even to the smallest of sites. These include an adequate supply of drinking water, sanitary and washing facilities, means to heat food and boil water, adequate outdoor protection including personal protective equipment (PPE), rest accommodation and facilities to eat meals, first-aid equipment under the control of an appointed person, and accommodation to change and store clothing.
  • Regulations 23 to 27: Site-wide issues. General requirements to ensure fresh air availability at each workplace, reasonable temperatures maintained at internal workplaces, protection against inclement weather, adequate levels of lighting (including emergency lights), reasonably clean and tidy workplaces, well-defined site boundaries, and maintenance of site equipment and plant for safe use by operatives.
  • Regulations 28 to 30: Training, inspection and reports. Specialised elements of work to be undertaken only by those appropriately qualified and/or trained.
  • Supervision of others by those suitably qualified may be acceptable. Places of obvious danger and risk, such as excavations, cofferdams and caissons, to be inspected regularly (at least daily and when changes are effected) by a competent person. Written records/reports to be filed after every inspection.
  • The principal considerations under the Work at Height Regulations apply to any place at or below ground level as well as above ground. They also include the means of gaining access and egress from that place of work. Measures taken by these regulations are designed to protect a person from injury caused by falling any distance. This may be from plant and machinery or from equipment such as scaffolding, trestles and working platforms, mobile or static. In summary:
  • Regulation 4: Organisation and planning. It is the employer’s responsibility to ensure that work at height is planned, supervised and conducted in a safe manner. This includes provisions for emergencies and rescues, and regard for assessing risk to persons working during inclement weather.
  • Regulation 5: Competence. Employer’s responsibility to ensure that persons engaged in any activity relating to work at height are competent. Any person being trained to be supervised by a competent person.
  • Regulation 6: Risk avoidance. Re risk assessment under Regulation 3 of the Management of Health and Safety at Work Regulations. This is concerned primarily with appraisal of the work task relative to its situation: that is, work should not be undertaken at a height if it is safer to do it at a lower level, e.g. cutting materials. Provisions to be in place for preventing persons sustaining injury from falling.
  • Regulation 7: Work at height equipment. Further requirements for assessment of risk relative to the selection of plant and equipment suitable for collective rather than individual use.
  • Regulation 8: Specific work equipment.
Scaffold and working platforms:
  • Top guard rail, min. 950 mm high.
  • Intermediate guard rail, positioned so that no gap between it and top rail or toe board exceeds 470 mm.
  • Toe board, sufficient to prevent persons or materials falling from the working platform. Generally taken as 150 mm min. height. For practical purposes a 225 mm wide scaffold board secured vertically.
  • Stable and sufficiently rigid for the intended purpose.
  • Dimensions adequate for a person to pass along the working platform, unimpeded by plant or materials.
  • No gaps in the working platform.
  • Platform surface resistant to slipping or tripping.
  • Platform designed to resist anticipated loading from personnel, plant and materials.
  • Scaffold frame of sufficient strength and stability.
  • If the scaffold is unconventional in any way, calculations are required to prove its structural integrity.
  • n Assembly, use and dismantling plan and instructions to be produced by a
  • competent designer. A standard procedure/plan is acceptable for regular
  • applications.
  • During assembly, alteration, dismantling or non-use, suitable warning signs
  • to be displayed as determined by the Health and Safety (Safety Signs and
  • Signals) Regulations. Means to prevent physical access also required.
  • Assembly, alteration and dismantling under the supervision of a competent person qualified by an approved training scheme.

Nets, airbags or other safeguards for arresting falls:

12 Advanced Construction Technology Used where it is considered not reasonably practical to use other safer work equipment without it. A safeguard and its means for anchoring must be of adequate strength to arrest and contain persons without injury, where they are liable to fall. Persons suitably trained in the use of this equipment, including rescue procedures, must be available throughout its deployment. Where personal fall protection equipment is considered necessary, it should be correctly fitted to the user, adequately anchored, and designed to prevent unplanned use by the user’s normal movements.

Ladders:

  • Used solely where a risk assessment indicates that it is inappropriate and unnecessary to install more substantial equipment. Generally, this applies to work of a short duration.
  • The upper place of support is to be firm, stable and strong enough to retain the ladder without movement. Position to be secured by rope lashing or other mechanical fixing.
  • Inclination is recommended at approximately 75° to the vertical, i.e. in the vertical to horizontal ratio of 4:1.
  • A suspended ladder to be secured and attached to prevent displacement and
  • swinging.
  • The extension of a ladder beyond a place of landing should be sufficient for safe bodily transfer – normally taken as 1.050 m min. measured vertically.
  • Where a ladder ascends 9.000 m or more vertically, landing points to be provided as rest platforms.
  • Regulation 9: Fragile surfaces. It is the employer’s responsibility to ensure that no person works on or near a fragile surface. Where it is impossible to avoid, then sufficient protection, e.g. platforms, guard rails etc., are to be provided. Location of fragile surfaces is to be indicated by positioning of prominent warning signs.
  • Regulation 10: Falling objects. See also Regulation 8 under the Construction (Health, Safety and Welfare) Regulations. Suitable provisions, e.g. fan hoardings, are required to prevent persons suffering injury from falling objects or materials. Facilities are to be provided for safe collection and transfer of materials between high and low levels, e.g. chutes. No objects to be thrown. Materials to be stacked with regard to their stability and potential for movement.
  • Regulation 11: Dangerous areas. Areas of work of specific danger, e.g. demolition, to be isolated to ensure that persons not engaged in that particular activity are excluded. Warning signs to be displayed.
  • Regulations 12 and 13: Inspection. These regulations specifically apply to scaffolding, ladders and fall protection equipment. After installation or assembly, no equipment may be used until it has been inspected and documented as safe to use by a competent person. Further inspections are required where conditions may have caused deterioration of equipment, or alterations or changes have been made. Following an interval, every place of work at height should be inspected before work recommences.
  • Regulation 14: Personnel duties. Persons working at height should notify their supervisor of any equipment defect. If required to use personal safety/protective equipment (PPE), individuals should be adequately trained and instructed in its use.

Under the Health and Safety at Work etc. Act employers must have defined duties, which include providing:

  • a safe place of work;
  • safe access to and egress from places of work;
  • safe systems of work;
  • safe items of plant and equipment;
  • suitable and adequate training, supervision and instruction in the use of equipment;
  • suitable and appropriate PPE applicable to head, hands, feet, eyes and mouth;
  • materials and substances that are safe to use (COSHH Regulations 1999);
  • a statement of health and safety policy.

Employees and the self-employed have duties to ensure that they do not endanger others while at work. This includes members of the public and other operatives on site. They must cooperate with the health and safety objectives of their employer (the main contractor), not interfere with any plant or equipment provided for their use, other than its intended use, and report any defects to equipment and dangers relating to unsafe conditions of work.

The preceding section on provision of facilities under the Construction Regulations, the Work at Height Regulations and the Health and Safety at Work etc. Act is intended as summary comment for guidance only. For a full appreciation, the reader is advised to consult each specific document. These are published by The Stationery Office, www.tso.co.uk.

ACCOMMODATION

Apart from legislative necessities, the main areas of concern will be sizing, equipping and siting the various units of accommodation. Mess huts

These are for the purposes of preparing, heating and consuming food, which may require the following services: drainage, light, power, hot and cold water supply.
To provide a reasonable degree of comfort a floor area of 2.0 to 2.5 m2 per person should be allowed. This will provide sufficient circulation space, room for tables and seating, and space for the storage of any utensils. Consideration can also be given to introducing a system of staggered meal breaks, thus reducing space requirements. On large sites where full canteen facilities are being provided this will be subcontracted to a catering firm. Mess huts should be sited so that they do not interfere with the development of the site but are positioned so that travel time is kept to a minimum. On sites that by their very nature are large, it is worthwhile considering a system whereby tea breaks can be taken in the vicinity of the work areas. Siting mess huts next to the main site circulation and access roads is not of 14 Advanced Construction Technology major importance. It is the principal contractor’s responsibility to ensure that
reasonable welfare facilities are available on site, although they do not necessarily have to provide these. It may be part of subcontractors’ conditions of engagement that they provide their own.

Drying rooms

Used for the purposes of depositing and drying wet clothes. Drying rooms generally require a lighting and power supply, and lockers or racks for deposited clothes. A floor area of 0.6 m2 per person should provide sufficient space for equipment and circulation. Drying rooms should be sited near or adjacent to the mess room.

Toilets

Contractors are required to provide at least adequate washing and sanitary facilities as set out in Regulation 22 of the Construction (Health, Safety and Welfare) Regulations. All these facilities will require light, water and drainage services.

If it is not possible or practicable to make a permanent or temporary connection to a drainage system, the use of chemical methods of disposal should be considered.

Sizing of toilet units is governed by the facilities being provided, and if female staff are employed on site separate toilet facilities must be provided. Toilets should be located in a position that is convenient to both offices and mess rooms, which may mean providing more than one location on large sites.

First-aid rooms

Only required on large sites as a specific facility, otherwise a reasonably equipped mess room will suffice. The first-aid room should be sited in a position that is conveniently accessible from the working areas, and must be of such a size as to allow for the necessary equipment and adequate circulation, which would indicate a minimum floor area of 6 m2. First-aid equipment must be under the charge of a suitably trained, appointed person, with responsibility for accounting for the contents and their use.

Before the proposed site layout is planned and drawn, the contracts manager and the proposed site agent should visit the site to familiarise themselves with the prevailing conditions. During this visit the position and condition of any existing roads should be noted, and the siting of any temporary roads considered necessary should be planned. Information regarding the soil conditions, height of