Last edited 25 Sep 2020

Specialist subcontractor

‘Specialist contractor’ is a very broad term that describes a contractor appointed to carry out activities in the development of a built asset that involve specialist construction knowledge and skills. This is as opposed to a ‘general contractor’ who will typically have a range of general construction knowledge and skills.

Typically, general contractors are tier 1, main contractors, working directly for the employer and are in overall charge of construction works. Specialist contractors are generally tier 2 subcontractors working for the main contractor to carry out a specialist part of the construction works. For this reason, they are sometimes referred to as ‘specialist subcontractors’.

However, the construction supply chain is increasingly complex and varied, and so a specialist contractor might be employed directly by an employer (for example to remove asbestos from a building). Similarly, a general contractor might be employed by a main contractor to carry out general construction works on their behalf and so might be referred to as a ‘subcontractor’.

To further complicate the supply chain, specialist subcontractors may have their own suppliers of materials, labour and components, and in some cases, these suppliers may be larger, more general contractors, than the specialist contractor.

The even wider term 'specialist' may be used to refer to specialist contractors, specialist suppliers (such as suppliers of specialist materials or plant) or specialist consultants (such as specialist designers).

The definition of what constitutes ‘specialist’ is not clear, however, examples of areas that might involve a specialist subcontractor could include:

Cladding and glazing.
Specialist finishes.
Building services.
Information and communications technology.
Lifts and escalators.
Fire protection.
Drilling.
Piling.
Flooring.

In addition to providing construction services, increasingly, specialist subcontractors undertake aspects of technical design. Earlier engagement with specialist subcontractors is also possible, and it is common during the ‘developed design’ or ‘detailed design’ stage for the project team to consult with specialist subcontractors to begin to address specific aspects of the design.

Early design input can be secured from specialist subcontractors before the supply contract has been agreed by:

Informal agreement.
Writing a closed specification that could only be satisfied by the specialist subcontractor.
A two-stage tender process where the specialist subcontractor's design services are procured in the first stage along with agreed rates, overheads and profit for the products or services to be supplied in the second stage.

It is important that appointment documents make it clear who has responsibility and liability for different aspects of the design at different stages of the project and the level of detail that they will be expected to produce. Where building information modelling (BIM) is being used, handover of an element of the design to a specialist may require a 'change of ownership' procedure for those parts of the model.