Development proposals may include specialist components that are best designed in detail by their manufacturers or installers. Such items could include; lifts, escalators, cladding systems, switchgear, refrigeration units, heating ventilation and air conditioning (HVAC) systems, cleaning cradles and so on.
In such cases it is often desirable to secure this specialist design before the supply contract has been tendered in order that they can be properly integrated into the overall design and so that delays do not occur and variations are not necessary.
Design input by specialist contractors can be secured before the contract for the supply of those components has been executed by:
- Writing a closed specification for specific components that could only be satisfied by the specialist contractors.
- A two-stage tender process where the specialist contractors 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. The specialist contractor might then become a named sub-contractor or nominated sub-contractor, or a named supplier in the main contract. In some cases, the second stage appointment might be made direct by the client (for example for the supply of equipment outside of the scope of the main contract).
A design co-ordinator might be appointed within the consultant team to ensure proper integration and co-ordination of specialist contractors designs into the overall design.
On publicly-funded projects, OJEU procurement rules may apply to the appointment of a specialist contractors if the potential cost of the contract exceeds the relevant threshold.
For information about commencing work with a specialist contractor see: Specialist contractors' start-up meeting.
 Related articles on Designing Buildings Wiki
- Building information modelling.
- Collaborative practices.
- Main contractor.
- Nominated sub-contractor.
- Named sub-contractor.
- Named supplier.
- Procurement routes
- Specialist designer.
- Specialist contractors' start-up meeting.
- Specialist subcontractor.
- Tender process.
- Two-stage tender.
- Types of contractor.
- Working with landscape maintenance contractors.