Who Can Take the Role of Principal Designer?
On small domestic projects, the Principal Designer is usually:
The architect or building designer involved in the design and planning stage.
A building surveyor, particularly if they are managing both design and compliance.
A design-and-build contractor, where the contractor provides both design and construction services.
In small domestic construction projects — such as home extensions, loft conversions, renovations, or self-builds — the Principal Designer typically takes on a key leadership and coordination role during the design phase. While the term is commonly associated with CDM, it can also refer more broadly to the lead designer responsible for managing and integrating the design process.
Main Responsibilities:Design Oversight & Coordination
Leads the overall design vision and ensures that all aspects (architecture, structure, services) work together coherently.
Coordinates inputs from other consultants (e.g., structural engineer, M&E designer, energy assessor) to produce a complete and integrated set of drawings.
Client Adviser
Acts as the client’s main point of contact during the design phase.
Translates the client’s ideas, budget, and aspirations into a workable design proposal.
Advises on material choices, sustainability, buildability, and aesthetics.
Planning and Regulatory Compliance
Prepares and submits planning applications.
Ensures designs comply with Building Regulations and other statutory requirements.
May assist in preparing or coordinating other approvals (e.g., Party Wall Notices, Thames Water build-over agreements).
Technical Detailing
Produces or oversees production of detailed construction drawings and specifications.
Resolves junctions, insulation build-ups, drainage layouts, and material interfaces to ensure buildability.
Cost Awareness
Balances design quality with cost considerations.
Could works closely with the quantity surveyor (if involved) or builder to keep the design aligned with budget expectations.
Supporting Tendering & Construction
Provides design support during construction, responding to minor queries, minor updates to drawings, or approving minor changes.