Principal Designer Role

The difference between CDM Principal Designer role and Building Regulations Principal Designer role

The CDM Principal Designer role and the Building Regulations Principal Designer role are separate legal dutyholder roles with different responsibilities. The CDM Principal Designer focuses on health and safety risks during construction and maintenance under the Construction (Design and Management) Regulations 2015. The Building Regulations Principal Designer focuses on compliance with the Building Regulations under the Building Safety Act dutyholder regime.

A CDM Principal Designer plans, manages and coordinates health and safety during the pre-construction phase. The role addresses risks such as working at height, structural stability during construction and safe future maintenance. A Building Regulations Principal Designer coordinates the design team to ensure the completed building complies with the functional requirements of the Building Regulations. This includes areas such as fire safety, structure, energy efficiency, accessibility and moisture control.

Although the roles often overlap in practice, they are not interchangeable. A designer may act as both dutyholders if they can demonstrate the required competence for each role. For domestic clients, the distinction is important because even relatively simple residential projects may require both health and safety coordination and formal management of Building Regulations compliance.

What is the role of a Building Regulations Principal Designer?

A Building Regulations Principal Designer plans, manages and monitors compliance with the Building Regulations during the design phase of a project. The role supports designers in coordinating information, identifying compliance risks and ensuring the design meets the functional requirements of the Building Regulations. Under the Building Safety Act dutyholder regime, the Building Regulations Principal Designer must demonstrate competence, coordinate design teams and help clients fulfil their legal duties. The role applies to all projects involving more than one contractor and plays a critical part in achieving safe, compliant and buildable design solutions.

For domestic clients, the role often applies to house extensions, loft conversions and refurbishment projects where several contractors or designers contribute to the work. Although these projects are usually less complex than commercial developments, they still require compliance with the Building Regulations. A Building Regulations Principal Designer helps domestic clients understand their responsibilities, coordinate technical information and reduce the risk of non-compliant design work progressing to site.

What competence does a BR Principal Designer require?

A Building Regulations Principal Designer must demonstrate the skills, knowledge, experience and organisational capability needed to coordinate compliance with the Building Regulations during the design phase of a project. Competence requirements arise under the Building Safety Act dutyholder regime and align closely with PAS 8671 and the wider industry competence framework.

A competent BRPD should understand how design decisions affect compliance with areas such as fire safety, structure, energy efficiency, accessibility and moisture management. The role also requires the ability to coordinate designers, manage compliance information and identify risks before construction begins.

For domestic projects, the required level of competence should reflect the scale and complexity of the work. Smaller residential projects still require a clear understanding of the Building Regulations and effective coordination between the design team and contractor.

Can architects undertake the BR Principal Designer role?

Yes. Architects can act as Building Regulations Principal Designers where they can demonstrate the required competence to coordinate compliance with the Building Regulations during the design phase. The role suits many architectural practices because architects often lead design coordination, manage technical information and advise clients on statutory compliance.

However, the role is not automatic. An architect acting as BRPD must have the appropriate skills, knowledge, experience and organisational capability for the specific project. This includes understanding how the design complies with areas such as fire safety, structure, energy efficiency and accessibility under the Building Regulations.

For domestic projects, architects frequently undertake the BRPD role on house extensions, loft conversions and refurbishment works where they already coordinate the wider design team and support the client through the approvals process.

Can clients act as BRPD?

A client can act as the Building Regulations Principal Designer if they have the necessary competence to fulfil the role. However, this is rarely appropriate in practice. The Building Regulations Principal Designer must coordinate compliance across the design team, understand the technical requirements of the Building Regulations and identify compliance risks before construction begins. Most clients, particularly domestic clients, do not possess the technical knowledge or construction experience needed to discharge these duties effectively.

Although the legislation does not prevent clients from taking on the role, doing so may conflict with the wider intention of the Building Safety Act dutyholder regime. The legislation aims to improve accountability, competence and regulatory oversight within the construction industry. Appointing an experienced designer with appropriate technical expertise forms a key part of that objective.

For domestic projects, clients should approach the role with caution. House extensions, loft conversions and refurbishment works may appear straightforward, but they still involve complex compliance requirements relating to structure, fire safety, insulation, ventilation and moisture control. A competent Building Regulations Principal Designer helps coordinate this information, reduce compliance risk and support the client through the design and construction process. They provide an important bridge between the client and the building inspector.

I am a client, I have not appointed a BRPD and I’m halfway through the construction but the principal contractor has changed the design. The Building Inspector is asking for information that I cannot provide?

If a client has not appointed a Building Regulations Principal Designer and design changes arise during construction, responding to Building Control requests can quickly become difficult. Building Inspectors may request updated drawings, technical details, product information or evidence demonstrating compliance with the Building Regulations. Without a competent designer coordinating this information, clients often struggle to understand what information is required or how proposed changes affect compliance.

This situation commonly occurs on domestic projects where construction begins with limited technical design information and details evolve on site. However, design changes relating to structure, fire safety, insulation, drainage or ventilation can all affect Building Regulations compliance. Informal decisions made during construction may also create conflicts between different parts of the design.

A Building Regulations Principal Designer helps manage this process by coordinating the design team, reviewing proposed changes and ensuring updated information remains compliant before work proceeds. Without this oversight, clients risk delays, additional costs and difficulties obtaining final Building Control approval.

Construction is now complete, I have managed to get to the end without a BRPD, but I haven’t provided building control with all the information they require. What happens now?

If construction completes before the required compliance information has been provided to Building Control, the project may not receive a Completion Certificate. This can create significant problems for the client, particularly when selling, refinancing or insuring the property. Building Control may request further drawings, calculations, specifications, photographs or evidence demonstrating that the completed work complies with the Building Regulations.

This situation often arises where projects progress without a clearly coordinated design process or where design changes occur during construction without proper technical review. In some cases, contractors or clients assume compliance can be demonstrated retrospectively at the end of the project. However, once work becomes concealed, it can be difficult to prove that critical elements such as structure, insulation, fire protection or drainage comply with the Regulations.

Where information gaps exist, Building Control may request intrusive investigations, or additional remedial works before issuing approval. A Building Regulations Principal Designer helps reduce this risk by coordinating compliance information throughout the design and construction process rather than attempting to resolve issues retrospectively after completion.

Can I appoint a BRPD retrospectively, who hasn’t been involved in the construction?

A client can appoint a Building Regulations Principal Designer retrospectively after construction has started, or even after completion, but this approach carries important limitations and risks. A BRPD who has not been involved throughout the design and construction process may have limited ability to verify how compliance decisions were made, what changes occurred on site or whether completed work satisfies the Building Regulations.

The Building Regulations Principal Designer role centres on planning, managing and monitoring compliance during the design phase. Appointing a BRPD late in the project may therefore conflict with the intended purpose of the dutyholder regime, which aims to embed competence and compliance management from the outset of a project rather than retrospectively.

In practice, a retrospective BRPD appointment often involves reviewing available drawings, specifications, Building Control comments and site records to identify gaps in compliance information. However, where critical elements of the work are concealed or undocumented, additional investigations or opening-up works may still be required. Clients should therefore avoid treating retrospective appointment as a substitute for proper compliance coordination during the project itself.