The Principal Designer Role: What It Means for Your Project

The Building Safety Act 2022 and the updated Building Regulations introduced mandatory dutyholders for projects subject to Building Regulations approval. For most domestic projects — extensions, loft conversions, structural alterations — there are two key roles: the Principal Designer (PD) and the Principal Contractor (PC).

What Is the Principal Designer?

The Principal Designer is the person or organisation responsible for planning, managing, monitoring, and coordinating health and safety during the pre-construction phase — specifically the design phase. The PD must ensure that:

– Design work takes account of the safe construction, maintenance, and eventual demolition of the building
– Structural and fire risks are adequately considered in the design
– Information is provided to other designers and contractors that enables them to carry out their work safely
– The Building Regulations submission is coordinated correctly

The PD is not just the structural engineer — it is the lead designer on the project. In most domestic projects, this is the architect or building designer who is coordinating the design information.

Who Holds the PD Role?

On a typical domestic project:

– If there is an architect: the architect takes the Principal Designer role
– If there is a designer (e.g. a measured survey company or a sole planning agent): they may take the PD role, or may need to appoint one
– If there is no designer of any kind: the main contractor may need to take both PD and PC roles

If you are unsure who holds the PD role on your project, clarify this before Building Regulations submission. Building Control will check that dutyholders have been appointed and may refuse to proceed without that confirmation.

What PorthouseDean’s Role Is

PorthouseDean is the structural engineer — a designer within the project team, but not the Principal Designer. We are responsible for our structural design work only. Our drawings and calculations are provided to the PD so they can be incorporated into the overall Building Regulations submission.

PorthouseDean cannot act as Principal Designer for the whole project. We can only take responsibility for the structural design element — not the other design disciplines (fire, thermal, accessibility, drainage) that the PD must coordinate.

Principal Contractor

The Principal Contractor manages health and safety during the construction phase. This is typically the main contractor on site.

What You Need to Do

Before submitting for Building Regulations approval, ensure:

1. A qualified and willing Principal Designer has been appointed in writing
2. The PD understands that they must coordinate all design information, including PorthouseDean’s structural package
3. The Principal Contractor has been identified for the construction phase

Contact us if you have questions about who should hold the PD role on your project.