The architectural, building services and structural engineering designs are now further refined to provide technical definition of the project and the design work of specialist subcontractors is developed and concluded. The level of detail produced by each designer will depend on whether the construction on site will be built in accordance with the information produced by the design team or based on information developed by a specialist subcontractor. The Design Responsibility Matrix sets out how these key design interfaces will be managed.
Using the design coordinated during the previous stage, the designers should now
be able to develop their Technical Designs independently, with a degree of autonomy. The lead designer will provide input to certain aspects, including a review of each designer’s work.
Once the work of the design team has been progressed to the appropriate level of detail, as defined in the Design Responsibility Matrix and the Design Programme, specialist subcontractors and/or suppliers undertaking design work will be able to progress their design work. The lead designer and other designers, where required as part of their Schedule of Services, may have duties to review this design information and to ensure that specialist subcontractor design work is integrated with the coordinated design.
By the end of this stage, all aspects of the design will be completed sufficient to submit for Buildings Regulation Approval. In a few projects, Stage 4b and 5 work occurs concurrently, particularly the specialist subcontractor design aspects. An example of the tasks required of this Stage are:
- Prepare Developed Design, including coordinated and updated proposals for structural design, building services systems, outline specifications, Cost Information and Project Strategies in accordance with Design Programme.
- Review and update Sustainability, Maintenance and Operational and Handover Strategies and Risk Assessments.
- Undertake third party consultations as required and conclude Research and Development aspects.
- Review and update Project Execution Plan, including Change Control Procedures.
- Review and update Construction and Health and Safety Strategies.
- During this stage it is essential to review the Project Strategies previously generated.
The 'output' of this Stage is the Technical Design of the project completed sufficiently to submit for a Building Regulations submission.