The architectural design
Room arrangements, appearance, finishes and the integration of building elements sit within the architectural designer's usual role. The structural engineer then helps establish whether the proposed arrangement can be supported and what structural members or changes it needs. On a simple alteration, one suitably competent professional may provide several services; more involved projects require coordinated specialist input. [1]
Use the appointment to identify deliverables rather than relying on job titles. Ask who prepares the planning drawings, detailed construction information, structural calculations and specifications. Also establish whether the same person will answer questions during construction or whether another appointment is needed.
The structural design
The engineer needs to understand the capacity, condition and integrity of the existing structure. IStructE describes a staged process of inspection, investigation, assessment and reporting to support decisions about alteration or reuse when information is incomplete. [2]
Ask which findings could affect the layout before treating it as final.
For a wide rear opening, for example, structural stability may require a frame rather than an isolated beam. Its columns and foundations must be accommodated in the design. That is an interface to resolve together, not a reason to let one drawing silently contradict another. [3]
Who coordinates the interfaces?
England's building-regulations guidance requires designers to consider how their work affects other design work and to cooperate with the project team. The building-regulations principal designer plans, manages and coordinates the design work for compliance. This is a defined responsibility, not simply another name for whoever first drew the plans. [4]
The CDM principal designer has a separate health-and-safety role during the pre-construction phase. It includes coordinating foreseeable risks in design and passing relevant information to the principal contractor. Clarify the appointment under each regime rather than assuming that an ordinary structural-calculations commission includes both roles. [5]
Where does the builder fit?
Under CDM, someone who prepares or changes drawings, specifications or calculations can be a designer. That can include a contractor making a design change; it is not confined to an architectural office. The change must therefore be considered and communicated through the appropriate design process. [6]
A useful project arrangement is to nominate one route for technical questions. Ask the builder to submit proposed changes through that route, and ask the designers to issue coordinated revisions rather than informal instructions that never reach the rest of the team.
Agree the division before work starts
Record who designs foundations, steel connections and temporary supports, who checks specialist suppliers' information, and who arranges inspections. HSE distinguishes temporary works from the completed structure and explains that they need their own planning and management. A permanent-works design should not be assumed to cover the contractor's propping arrangements. [7]