Last edited 13 May 2017


As buildings become increasingly complicated, so it becomes less and less likely that any one contractor will have the required skills to carry out all of the works necessary to construct them, and it may not make good commercial sense to take on new employees for one project that would then have to be laid off for the next.

Increasingly therefore, contractors will use sub-contractors to carry out particular elements of the works. Sub-contractors (or subcontractors) are sometimes referred to as 'subbies', or increasingly, simply as 'suppliers'.

Elements of the works that might be awarded to sub-contractors might include; piling, roofing, cladding, civil engineering, steelwork, plumbing, electrical services and so on.

There are three main types of sub-contractor:

The use of sub-contractors enables the main contractor to undertake more complex projects whilst not unacceptably increasing their risk, however, concerns have been expressed about the prevalence of sub-contractors because of a perception that the main contractor has less control over the skills and training of sub-contractor employees and so there may be a negative impact on quality and health and safety on site.

Sub-contractors might be managed by the contractors' sub-agent or package manager.

Increasingly, sub-contractors will themselves sub-contract elements of their package of works to other suppliers. This has resulted in the development of complex supply chains, with different tiers of suppliers, some of whom may be entirely unknown to the client. For more information see: Suppliers.

'Attendance' is the main contractor’s mark up for specific services it has to provide for individual sub-contractors. This might include items such as material handling, scaffolding and rubbish clearance. Attendance can be 'general attendance' describing items available site wide to all subcontractors, or 'special attendance' where items are specific to a particular contractor/subcontractor.

NB On management contracts the works will be carried out by 'works contractors' and on construction management contracts the works will be carried out by 'trade contractors', although technically trade contractors are not sub-contractors as they are contracted by the client, and only managed by the construction manager.

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