Principal designer duties explained
A working guide to the principal designer role under Part 2A of the Building Regulations 2010 in England: when one must be appointed, what regulation 11M requires, what competence means, and what has to be signed at completion.
What must a principal designer do under the Building Regulations?
Under Part 2A of the Building Regulations 2010 (England), the principal designer must plan, manage and monitor the design work during the design phase, and coordinate it so that, if built as designed, the work would comply with all relevant requirements. They must also make designers cooperate and comply with their own duties, share information with the principal contractor, and sign a statement at completion confirming those duties were fulfilled.
These duties have applied in England since 1 October 2023, when the Building Regulations etc. (Amendment) (England) Regulations 2023 (SI 2023/911) inserted Part 2A. They apply to almost all building work, not only higher-risk buildings. Minor work listed in Schedule 4 is exempt from the Part 2A client duties.
The role is separate from the principal designer under CDM 2015, which is about health and safety rather than Building Regulations compliance. A written appointment should make clear that it covers the Building Regulations duties, not just CDM.
Part 2A applies in England. Wales introduced its own dutyholder and competence regime, in Part 2B of the Building Regulations 2010 as they apply in Wales, from 1 July 2026, broadly aligned with CDM roles.
When must a principal designer be appointed?
Regulation 11D requires the client to appoint a principal designer and a principal contractor in writing where more than one contractor is, or is reasonably foreseen to be, working on the project. The principal designer must be "a designer with control over the design work".
Timing depends on the type of work. For higher-risk building work needing a building control approval application, the appointment must be made before the application is submitted. For any other project, it must be made before the construction phase begins. For higher-risk work, the client must also keep a written record of the steps taken when making the appointment.
Part 2A never leaves the role empty. If the client does not appoint, the duties fall to the client, or for domestic clients under regulation 11C, to the designer in control of the design phase.
What are the principal designer's duties?
The core duties sit in regulation 11M, on top of the general duties in regulation 11J and the designer duties in regulation 11K that every principal designer also carries. They run from the start of design to a signed statement at completion.
- 01
Plan, manage, monitor
Coordinate design so that, if built, it complies with all relevant requirements.
Reg 11M(1) - 02
Designers cooperate
All reasonable steps so designers share information and meet their own duties.
Reg 11M(2) - 03
Liaise with the PC
Share information and have regard to the principal contractor's comments.
Reg 11M(3) and (4) - 04
Hand over
A document of the arrangements made, to the client within 28 days.
Reg 11M(5) and (6) - 05
Sign at completion
Confirm the Part 2A duties were fulfilled.
Reg 16(4A) · HRB reg 40
The last duty depends on the first four. A principal designer can only sign at the end with a record of how compliance was planned and checked throughout.
1. Plan, manage and monitor the design work
Regulation 11M(1) requires the principal designer to "plan, manage and monitor the design work during the design phase" and coordinate it so the design, if built, would comply. "Relevant requirements" means the requirements of Schedule 1 (Parts A to T) and the other applicable regulations, to the extent they apply to the work. In practice that needs a documented approach to which requirements apply to which parts of the design, who is responsible for each package (including specialist and contractor-designed elements), how design information is reviewed before issue, and how compliance is evidenced rather than asserted.
2. Make sure designers cooperate and comply
Under regulation 11M(2), the principal designer must take all reasonable steps to ensure designers cooperate and share information, design work is coordinated, and designers comply with their own Part 2A duties. Those include reporting compliance concerns about other designers' work to the principal designer (reg 11K(4)).
3. Liaise with the principal contractor
Regulation 11M(3) and (4) require the principal designer to liaise with the principal contractor, share information relevant to planning, managing and monitoring the building work, and have regard to the contractor's comments on compliance. This matters most at the boundary between design and construction: contractor's design portions, late substitutions and design changes on site.
4. Assist the client and hand over at the end
If asked, the principal designer must help the client provide information to other designers and contractors. When the appointment ends, regulation 11M(5) requires a document setting out the arrangements made to plan, manage and monitor the design work, given to the client within 28 days. A replacement principal designer must review those arrangements so the design still meets the relevant requirements (reg 11M(6)).
5. Sign a compliance statement at completion
On a non-HRB project, regulation 16(4A) requires the completion notice to include a signed statement from each principal designer confirming they fulfilled their Part 2A duties. For higher-risk buildings, regulation 40 of SI 2023/909 requires a compliance declaration signed by the principal designer with the Gateway 3 completion certificate application. Where a declaration cannot be obtained, the reasons must be given.
The completion statement is the duty that turns the rest into a practical question: can you show how compliance was managed?
What competence does a principal designer need?
Regulation 11G requires an individual principal designer to have the skills, knowledge, experience and behaviours needed for the role, appropriate to the type of work. An organisation acting as principal designer needs organisational capability and must appoint a competent individual to manage the role.
Regulation 11Q defines organisational capability as "appropriate management policies, procedures, systems and resources". An architect or practice can be the principal designer, provided it meets regulation 11G and has control over the design work.
Individual PD
Personal competence for the type of work. Trainees may work under supervision but cannot be appointed.
Organisation as PD
Organisational capability, plus a named individual with the necessary competence to manage the role.
A firm appointed as principal designer is judged on its systems as well as its people. Regulation 11Q sets out what organisational capability means.
- Clients must check
- Regulation 11E requires anyone appointing a designer or contractor to take all reasonable steps to satisfy themselves of competence. For higher-risk work they must also ask about serious sanctions in the last five years.
- Loss of competence
- Regulation 11I requires a person who stops meeting the competence requirements to notify the relevant client, principal designer or principal contractor.
- PAS 8671
- Government guidance names PAS 8671 as the recommended competence framework. It is not mandatory, and meeting it is useful evidence but does not by itself guarantee legal compliance.
- Registers
- Several professional bodies, including RIBA and CIAT, run principal designer registers.
How the duties differ on higher-risk buildings
The Part 2A duties are the same in substance on every project. On higher-risk buildings in England, SI 2023/909 adds further requirements on top.
- The principal designer must be appointed before the Gateway 2 application.
- The principal designer runs a mandatory occurrence reporting system.
- Formal change control applies, with major changes needing approval from the Building Safety Regulator.
- A signed compliance declaration is required at Gateway 3.
A practical checklist for principal designers
- The appointment is in writing and covers Building Regulations duties, not just CDM.
- The client is aware of its duties before design work starts (reg 11K(1)).
- A compliance matrix is set up: requirements, responsible designer, evidence, status.
- Other designers know how to report concerns, and those reports are recorded.
- The flow of design information and changes is agreed with the principal contractor.
- Design decisions and compliance reviews are logged with dates.
- The 28-day handover document and the completion statement are planned from the start.
Where Avoice fits
A principal designer signs at the end on the strength of a record kept throughout. Most of the work is keeping that record current without adding a second job.
Principal designer tooling inside the Avoice Compliance module is coming. It is being built on tools practices already use in Avoice: the Building Regs Tracker, which maps design elements to requirements and evidence, and Project Record, which keeps a dated log of decisions. Practices can follow progress and register interest on the principal designer page.
Software can organise and flag. The principal designer still holds the duty, and still decides whether the design and its evidence are adequate.
Keep the record a principal designer signs against
Map design elements to requirements and evidence, keep a dated decision log, and register interest in the principal designer tooling now being built.
This guide is for general education and is not professional advice. Check Part 2A of the Building Regulations 2010 and the current GOV.UK guidance for your project before relying on any provision.