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Unit 10 Managing Sub-Contractors within a Construction Environment


Section 1. Sub-comtractors

Section 2. Organising Sub-contractors

Section 3. Managing Sub-contractors



Information and Guidance is available on how you should study

Study Guide


Assignment for Unit 10


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Instructions for

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Additional Learning Resourses




Additional Information

You should relate your responses to any of the tasks set in this unit to the documents listed below; these will provide information about the type and size of the project.  

Section 1



Section 2

Section 3

Unit aim: This unit is designed to meet the needs of construction managers, to give them knowledge of managing sub-contractors.

This unit has an Introduction and is divided into 3 study sections.


Section 1 Sub-contractors

10.1.1 Legal Requirements
10.1.2 Types of sub-contractor
10.1.3 Attendance

Section 2 Planning and Programming

10.2.1 Selecting the Sub-contractor
10.2.2 Liaising with Sub-contractors
10.2.3 Communication

Section 3 Managing Sub-contractors
10.3.1 Monitoring Work
10.3.2 Maintaining Records
10.3.3 Dealing with problems

Unit Recommended Reading

Cook, B & Williams, P, (2009) construction planning, programming and control (3rd Ed), Wiley-Blackwell; Chichester.

Books can be ordered from most bookshops or online from Amazon.

Before starting you should read the ‘Study Guide’ accessible from the link on the left.


It is very unusual for a contractor to undertake all the work in a contract with their own workforce. Even in minor construction projects the main contractor is likely to require the assistance of a trade or specialist firm.  Work undertaken by firms other than the main contractor are described as sub-contractors, although it is not uncommon to find specialist firms working on site beyond the normal jurisdiction and control of the main contractor, and consequently, not a sub-contractor within the generally understood description.

Employers may employ these firms directly and as such they are not to be considered as sub-contractors of the main contractor.  Provision is made within the contract so that such firms have access to the site and any facilities.

In this unit we will look at the factors relating to engaging sub-contractors and ensuring that they are organised and programmed to ensure the maximum efficiency of the work.

Please Note

All information contained in this Study Unit was considered correct at the time of writing but Students must not rely on information contained in the Study Unit and/or references for any purposes other than use within this CIOB qualification aim as legislation and working practices are constantly being revised and updated. Students are advised therefore to continually up-date themselves as to current legislation and construction practice and must not to rely on information contained within the Study Unit and/or references for practical applications in the workplace. Where legislation or construction practice has been superseded to that contained in the Study Unit Students should note this within their responses to the tasks.


Section 1. Sub-contractors

Learning outcome:  On completion the learner will know the types of and the requirements relating to sub-contractors.
10.1.1 Legal Requirements
10.1.2 Types of sub-contractor
10.1.3 Attendance

10.1.1 Legal Factors

Any sub-contractor must be willing to enter into a formal and binding form of sub contract under the same terms as the main contractor. As at common law for a contract to exist the following must apply:
  • Intention – all parties must have intended to enter a binding contract.
  • There is an offer and an acceptance - both parties must have accepted the agreement.
  • Consideration - There must be benefit to both parties - one party has a building build, the other receives money for building it.
  • Certainty – it must be definite
  • Capacity - Both parties must be able to enter into the contact - they must be over 18 and of sound mind.
  • Legal -The contract must be legal and be possible to fulfil.

In addition the sub-contractor must fulfil their responsibilities under a number of pieces of legislation. These include:

The Health and Safety At Work Act 1974

This is the primary legislation covering all health and safety in the UK with particular reference to the legal duties of employers, the self-employed and to a lesser extent, employees.

Sub-contractors and their employees have the following responsibilities:
  • To carry out their works in such a way to ensure, so far as is reasonably practicable, that they and other persons are not exposed to health and safety risks.
  • To provide information to all persons on site, not just their employees, about the aspects of their work that might affect their health and safety.
  • To exercise reasonable care for the health and safety of themselves or others who may be affected by their acts or omissions at work
  • To co-operate with the main contractor, as far as may be necessary, to enable them (the main contractor) to carry out their legal duties in health and safety matters.

The main contractor must check that the sub-contractor adheres to these duties as they (main contractor) are ultimately responsible and liability will rest with them.  


The Construction Design and Management (CDM) Regulations 2007

Superseded by:

Construction (Design and Management) Regulations 2015

The CDM Regulations place duties on all those who can contribute to the health and safety of a construction project. The Regulations place duties upon clients, designers, contractors and CDM Co-ordinators, and require the production of certain documents - the health and safety plan and the health and safety file.

Sub-contractors and their employees have the following responsibilities:
  • Plan, manage and monitor own work and that of workers
  • Check competence of all their appointees and workers
  • Train own employees
  • Provide information to their workers
  • Comply with the specific requirements in Part 4 of the Regulations
  • Ensure there are adequate welfare facilities for their workers
  • Check client is aware of duties and a CDM co-ordinator has been appointed and HSE notified before starting work
  • Co-operate with principal contractor in planning and managing work, including reasonable directions and site rules
  • Provide details to the principal contractor of any contractor whom he engages in connection with carrying out the work
  • Provide any information needed for the health and safety file
  • Inform principal contractor of problems with the plan
  • Inform principal contractor of reportable accidents, diseases and dangerous occurrences

The main contractor must provide adequate supervision and management to ensure all these duties are adhered to by the sub-contractor as he is liable as the principle contractor.

For details of the new act visit HSE Website

Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 RIDDOR

Employers, the self-employed and those in control of premises are required by law to report specified workplace incidents, such as work-related deaths, major injuries, 3-day injuries (those causing more than three day’s inability to carry out normal duties), work related diseases, and dangerous occurrences (near miss accidents).

It is a legal requirement to report incidents and ill health at work and the information gathered enables the Health & Safety Executive to gather the information about how and why risks arise and to investigate serious incidents.

Sub-contractors and their employees have the following responsibilities: 
  • To report any work related deaths, injuries, cases of disease, or near misses to the main contractor
  • Ensure the main contractor reports it to the Health and safety executive

Control of Substances Hazardous to Health Regulations (COSHH)

COSHH requires employers and the self-employed to control exposure to hazardous substances in order to prevent harm to or ill health of employees and non-employees alike.

Sub-contractors and their employees have the following responsibilities:
  • Assess the risks;
  • Decide what cautionary measures are needed and put them into action;
  • Control exposure by measures that are proportionate to the health risk;
  • Ensure that measures are used and maintained. Cary out checks where necessary;
  • Monitor the exposure - where adequate control of exposure cannot be achieved provide for suitable personal protective equipment;
  • Check and review regularly whether all elements of control measures are effective;
  • Inform and train all employees on the hazards and risks from the substances with which they work and the use of control measures developed to minimise the risks. Prepare procedures to deal with accidents;
  • Ensure all workers are trained and supervised appropriately.
All the above are carried out in conjunction with the main contractor as he is also responsible for the above duties and for providing any specialist needs, such as storage, so that the sub-contractor is able to comply with these responsibilities. 


The Control of Noise at Work Regulations 2005

The Control of Noise at Work Regulations 2005 place a duty on employer's within Great Britain to reduce the risk to their employees’ and the general publics’ health by controlling the noise they are exposed to whilst at work.

Sub-contractors and their employees have the following responsibilities:
  • Assess the risks to your employees and public from noise at work
  • Take action to reduce the noise exposure that produces those risks
  • Provide your employees with hearing protection if you cannot reduce the noise exposure enough by using other methods
  • Make sure the legal limits on noise exposure are not exceeded
  • Provide your employees with information, instruction and training
  • Carry out health surveillance where there is a risk to health.

These duties also apply to the main contractor but also they must ensure they pay particular attention to noise levels on site.


Task 10.1.1 Contracts
Describe the legal requirements of the contract and relate them to the appointment of a sub-contractor.



10.1.2 Types of sub-contractor

Not all the work on a contract will be carried out by the main contractor.  These days it is common to sub-contract various aspects of the job to other companies although the main contractor retains overall control and in most case responsibility. The most common reason for sub-contracting is due the main contractor not having the required skills within its own work force, although more and more theses day reduce the amount of directly employed labour due to financial reasons.

There are four types of subcontractors:
Domestic Sub-contractor

A  Domestic Sub-contractor is selected and engaged directly by the main contractor to carry out a particular trade, this will mainly include standard trades such as bricklayers, roofers, ground workers, plumbers, electrical and plasterers. They may be labour only or supply and fix. In all cases they must be approved by the architect under JCT 2005 Standard Building Contracts.  The architect has the full authority to reject any subcontractor requested by the contractor. The contract does not recognise the main contractors own subcontractors, any work carried out by these is taken as if it were carried out by the main contractor.

Nominated Sub-contractor
A Nominated subcontractor is chosen by the architect, client or engineer to carry out certain aspects of the work. They are appointed on the expenditure of a provisional sum or prime cost sum included in the contract bills. The nominated subcontractor enters into a contract with the main contractor but there may be a collateral warranty between the nominated subcontractor and the client. The main contractor has no responsibility to carry our work that is intended to be carried out by a nominated subcontractor. Nomination is not possible under the JCT 2005 Standard Building Contracts or the Engineering and Construction Contract. The main contractor is required to provide the general attendances for the subcontractor; any special attendances are the subcontractors’ responsibility. The main contractor will provide a profit margin for such attendance.


Named Sub-contractor

A named sub-contractor will often be chosen from a list of subcontractors provided by the architect. Under the JCT 05 standard or intermediate building contracts, the architect may provide the contractor with a list of at least three subcontractors to choose from for carrying out particular parts. The main contractor may, with approval from the architect, add subcontractors to the list. Although the subcontractor is named, they are a domestic subcontractor under the contract.

Labour only Sub-contractor

Labour only Sub-contractor includes self-employed individuals, agencies and small firms. It is useful in that it enables the contractor to take on temporary workers as and when required. This will reduce the overheads in that they are only paid when working and there is not national insurance contribution. It is essential to take care in selecting as there can be problems with regard to quality of work and safety awareness. 

Task 10.1.2  Sub-contractors

Describe the differences between the obligations attached to the main contractor in respect of the following and describe when each would be used:
  • Domestic
  • Nominated
  • Named
  • Labour only


10.1.3 Attendance

When a sub-contractor is used it falls to the main contractor to provide the sub-contractor with certain facilities and assistance, this is known as Attendance. This can fall into general attendances such as:
  • Power and Water
  • Welfare facilities
  • Toilets
  • Site parking
  • Secure plant and material storage

In addition specific types of attendance may be required so these will need to be identified.

Attendance can fall into the following categories:

General attendance
  • Plant
  • Scaffolding
  • Welfare
  • Toilets
  • Water
  • Access/Egress
  • PPE
  • Power
  • Hoists

Special attendance
  • Storage
  • Hard Standings
  • Task Lighting 

Sub-Contractors must provide their own specialist equipment which is not generally on site and this should be agreed before commencement.

Sub-Contractors materials are the responsibility of Sub-Contractors although the Main Contractor may unload and distribute it. Any requirements with regard storage must be agreed from the onset, as must the provision of any steps, trestles and towers below 3.3M


Task 10.1.3 Attendance

Explain the responsibility of the contractor and sub-contractor for special attendance/general attendance.



Section 2. Organising Sub-contractors

Learning outcome:  On completion the learner will know how to select and organise sub-contractors.


10.2.1 Selecting the Sub-contractor
10.2.2 Liaising with Sub-contractors
10.2.3 Communication

10.2.1 Selecting the Sub Contractor

In selecting a sub-contractor the contractor will need to consider the following main factors:
  • Price
  • Technical ability
  • Quality
  • Co-operation

This can be expanded to assess the following:
  • Price
  • Past performance
  • Health and safety record
  • Financial capability
  • Current workload
  • Reputation
  • Past relationships
  • Resources (both physical and human)
  • Technical/ managerial capability
  • Number of years the firm has been working in the market
  • References
  • Location of firm
  • Experiences firm has of similar projects
  • Appropriate insurance cover
It is normal to invite a sub-contractor to tender for a contract and this can be done using a standard letter. It will include a Bill of Quantities and a Form of Tender which will be used to gather the information in the list above.

This will involve a meetings with the sub-contractor to confirm the above and also find out what skills and qualifications their operatives have to make sure they are qualified for the job and to check that they have the correct method statements and risk assessments in place, make sure they have a good health and safety record and also that they have the correct insurances in place. 

Sub-contract quotations are usually obtained during the main contractor’s tender preparation period using the company’s standard procedure.

The documentation will usually comprise:
  • The  main contractors terms and conditions of contract
  • Extracts from the Bills of Quantity relating to the specific operation required of the Subcontractor.
  • Applicable extracts from the Preliminaries and Preambles/specification
  • Applicable tender drawings

The main contractor may also at this stage require day work rates to be stated by the sub -contractor should additional works be required. They will also notify the subcontractor of the form of contract they will be required to enter into if their quotation is successful. It is usual for the transfer of all information to take place by electronic means both to and from the parties.

Assuming the main contractor selects and approves the quotation of the subcontractor and is satisfied that the sub-contractor is fully capable of carrying out the work to the required programme and quality (comply with the requirements of all aspects of the Bills of Quantity); it is usual for the main contractor to require that the sub-contractor enters into a formal contact. This being a domestic sub-contractor agreement under the same terms and conditions as the main contractor and related to the form of contract under which the main contract is to be executed.


Task 10.2.1 Procedure for Obtaining Sub-contractors

Outline the procedures used by your company to obtain sub-contractors.



10.2.2 Liaising with Sub-contractors

Prior to any work commencing it is essential that the site manager ensures that the sub-contractor will be available when they are required on site.  In order to assess when they are required a programme will have been produced detailing when each aspect of the job is to be done and the length of time that it will take (This was studied in Unit 1 Project Planning). Liaison with contractors is required to determine the length of time and to ensure that it fits in with the overall programme. All these things will have been confirmed prior to the award of the contract but the site manager needs to liaise on this with the sub-contractor. A programme specifically for sub-contractors can be drawn up to allow the main contractor to monitor and control the work.

Prior to the production of the programme the work to be carried out by the sub-contractor is specified within the tender documents which allow the sub-contractor to produce their Method Statements determining the way the work is to be carried out and the length of time required according to the resources allocated.

The site manger will need to confirm prior to any work commencing that a risk assessment has been carried out by the Sub-contractor and that all aspects relating to safety have been considered.

Any failure by the sub-contractor to complete the work according to the programme can have a knock on effect for the programme and other sub-contractors as the failure to complete one aspect of work by a certain date means that any subsequent sub-contractors cannot start as planned.  If subsequent sub-contractors have other jobs which they are committed to that can create problems for the main contractor.


Site Requirements

The process of liaising will determine the requirements of the sub-contractor. The allocation of site storage areas will be set out by the site manager. Different trades will have different storage requirements. As will the type and size of job, the site manager will consider these factors in determining the requirements.

Other requirements such as the use of a crane, hoist etc need to be determined and arrangements made.


Work Requirements

The detailed requirements for the work will have been sent to the sub-contractor at the tender stage so they will know exactly what is required. The site manager will need to ensure that the work is programmed in to the overall programme and that the sub-contractor is available when required. A method Statement will need to be assessed and approved by the site manager prior to the sub-contractors arrival on site and the commencement of the work.  Any changes to the work must be communicated to the sub-contractor.


Task 10.2.2. Programming Work

Produce a short-term programme for one of the trade sub-contractors which will be incorporated into the main contractors programme. 


Integrating Work

The programme produced will indicate when each sub-contractor is required and the dependency of each on others for instance the painters cannot begin work until the plastering has been completed and it has had sufficient time to dry. Programming was looked at in Unit 1 Project Planning so you should be familiar with the requirements of a programme and how to produce one. The production of the programme must take into account the resources that the sub-contractor has and the requirements for the completion of the contract.


Task 10.2.3 Site Requirements

Compare the likely site requirements needed by a Curtain walling contractor to that of an electrical contractor.



10.2.3 Communication

Communication is essential if the project is to run smoothly. It is also worth remembering that it is a two-way thing and you should establish a good system of communication with the sub-contractor in order to communicate and relay information to them but also to ensure that they provide you with information. The system must also be in place to ensure that information is passed on to the appropriate person in a timely and efficient manner.

The process of communication between the main contractor and sub-contractor relates to the three stages of the work.  These are:
  • Pre-contract
  • Contract Period
  • Post Contract


This relates to design criteria, the requirements of specification, codes of practice and co-ordination of design in so far as they relate to sub contractors. Checks will need to be made to confirm the following:
  • Design checklist
  • Design programme
  • Co-ordinated overlays of mechanical engineering and sub-contractors layouts
  • Builders work details
  • Outline specifications
  • List of secondary design information relative to other trades

Contract Period

This relates to:
  • After the awarding of contract before work commences
  • During the Build process
Communication will be carried out through:
  • Verbal discussions on a one to one basis
  • Inductions
  • Tool box Talks
  • Progress meetings
  • Written Instructions
  • Memos
  • Architects Instruction
  • Variation Orders

Post Contract

It is essential on completion to determine how the work went with regard to the sub-contractor. On the completion of the work they carried out their work will need to be inspected to ensure that it conforms to the requirements and specification. This will normally incorporate a Snagging Inspection and report which will require the sub-contractor to remedy any faults within a specified period.

This will highlight any problems and enable them to be rectified in the event of any future contracts; it will also provide feedback to both parties in order that any future working relationships between the parties can be improved.


Task 10.2.4 Communications

Give examples of where communication has broken down between the main and sub-contractor and state the actions that were taken to rectify the situation.



Section 3. Managing Sub-contractors

Learning outcome:  On completion the learner will know how to monitor and maintain records of the work and deal with any problems relating to sub-contractors.


10.3.1 Monitoring Work
10.3.2 Maintaining Records
10.3.3 Dealing with problems

10.3.1 Monitoring Work

It is the Site Managers responsibility to supervised the work as it progresses, ensuring that it is completed to the requirements of the contract documentation, each stage of the work will be assess as it progresses and on completion by the supervisor and contract team before it is accepted.  The architect will be present at final acceptance and it is normal practice to produce a snagging list prior to hand over of the building of sections of the building. All work found to need attention will be remedied before acceptance.

The Architect will produce the required certificates following inspections and completion of the building.

Sub contract progress is constantly monitored by site meetings informal and formal and importantly by establishing and maintaining good relationships with the sub-contractor.

The contract programme should be updated on a daily basis to illustrate progress made.

It is sound policy to maintain a daily site diary which would contain the amount and type of sub-contractors personnel on site and compare this with the programmed and anticipated attendance thus discrepancies are quickly highlighted and suitable timely action taken to remedy the issues. When awarding the sub-contract the main contractor will ensure that the sub-contractor is willing to abide by the contract programme and provide the required resources to meet the time scales required.

The maintenance of this aspect of the site diary will also provide a record of events should a contractual dispute arise.

The use of preformed site diaries is now common and will contain sections where the required information can be entered.

The site manager must constantly monitor the work to ensure that it is completed as specified and that it meets the organisational requirements. Monitoring will enable any problems to be identified at the earliest convenience in order that they can be rectified without having a ‘knock-on’ effect.

The management of Architects instructions and Variation orders will be considered in the next section. 



One of the main things that must be monitored to ensure compliance is that of the quality of the work.  Quality is dealt with in detail in Unit 3 Managing the Quality of Site Work. Although it must be stressed that all work must be accepted by the site manager as meeting the specification and a requirement before it is approved for payment.


Task 10.3.1 Monitoring Work

Provide an overview of the procedures used by your company to monitor work carried out be a sub-contractor.



10.3.2 Maintaining Records

In many respects the checking procedures for materials and sub-contracts commence well before these services arrive on site; the importance of sound quotation request, analysis and ordering cannot be overemphasised.

Once work commences on site it important to ensure that architects instructions (AI) and variation orders (VO)  are recorded accurately and the effects of such instructions ascertained, they must be passed onto any sub-contractor affected by the instruction without delay; thus also giving them the chance to raise questions or objections.

Careful records of AI and VO are essential which will include:
  • The Quantity of works added or omitted
  • Effects on completed work or materials ordered or stored
  • Cost implications
  • Programme implications and effects on other trades.
All may be the subject of contractual claims under the form of contract and without records the validity of claims may be disputed.

Day work records are an excellent method of maintaining records of the any additional work required but it is important to note that specific rules apply to the payment of additional works.    

The maintenance of records will also enable the verification of sub-contractors claims. 


Task 10.3.2 Recording Work

List and outline the information that needs to be recorded in order to monitor the work carried out by a sub-contractor and appraise the risks associated with the use of Sub-contractors.


10.3.3 Dealing with Problems

However if it is assumed that the quotation has been fully assessed and the ordering process accurate, the receipt of materials onto site is relatively straight forward; always providing the person off loading and accepting the materials has been trained to do so and is expecting the materials.

Supplies from whatever source must be checked off on site by a competent person who has an exact understanding of the materials being delivered. The site check must be completed against the original purchase order to ensure that the materials being delivered are correct in quantity and to specification and also that all ancillary parts are delivered at the same time as the original article. Any damaged or missing items must be noted on the delivery note and a letter or e-mail sent to the supply company requiring immediate delivery or replacement of missing or defective items. 

It is inadvisable to off load damaged items or those not to the original order requirements, these should be sent back with the driver and this action noted on the delivery ticket and follow up correspondence.

Any deliveries which cannot be checked off thoroughly at the time of delivery on site should be signed for as unexamined, this will usually allow a short time for thorough checking and verification that the order requirements have been met.

In the event of work being unsatisfactory the site manager should request that sub-contractors remove defective materials or make good defective work as soon as possible.


Task 10.3.3 Dealing with Problems

Using examples, highlight the likely areas that problems can occur and how you would deal with them.


Breach of Contract
A breach of contract occurs when there is a failure to carry out the conditions of the contract. In the event of a serious breach the other party may act as if the contract were terminated. Examples of this may be due to:
  • The contractor stopping work and leaving the site
  • The contractor fails to complete the work
  • The contractor fails to rectify defective work
  • The employer fails to pay the sum due on the dates stated in the contract.
A contract may be determined (terminated) in the following cases:
  • Breach of Contract
  • Frustration
  • Agreement
If we have a contract we have a duty to fulfil the conditions of that contract, if we fail to do that the other party may have a remedy for breach of that duty, this remedy may be:
  • specific performance where the court orders that the contract is performed as specified
  • injunctions – the court prohibits the breaking of the contract or
  • award of damages which allows the person who suffers loss to claim financial compensation for the loss.

Task 10.3.4. Remedies

Evaluate contractual remedies when Sub-contractors fail to uphold their contractual obligations.


Unit Complete
You have now completed Unit 10, and you should complete the assignment and send it to

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