Quick summary: Building Regulations Principal Designer
A Building Regulations Principal Designer is the designer who takes control of the design work and helps coordinate it so that, if the project is built in accordance with the design, it complies with the Building Regulations in England. The dutyholder regime was introduced as part of the building safety reforms that came into force on 1 October 2023.
- For projects involving more than one contractor, the Building Regulations dutyholder regime normally requires a Principal Designer and Principal Contractor to be identified.
- For domestic homeowners, you do not necessarily need to employ a completely separate consultant. If you do not make a specific appointment, the designer who controls the design phase can become the Principal Designer.
- The role is about Building Regulations compliance – coordinating designers, checking the design process and helping make sure relevant requirements are properly addressed.
- It is different from the CDM Principal Designer role, which concentrates on managing health and safety risks during the pre-construction phase, although the same suitably competent person or organisation can perform both roles.
- Competence matters. The person or organisation taking the role must have the skills, knowledge, experience and behaviours – and, where relevant, organisational capability – appropriate to the project.
For a normal extension, loft conversion or home alteration, this often means confirming early who is coordinating the architectural, structural and other design information rather than assuming your architect, technician or builder has automatically accepted the responsibility.
Not sure who is responsible for Building Regulations compliance on your project?
We can help you identify the designers, contractors and building control steps your home project is likely to need before work starts.
What is a Building Regulations Principal Designer?
The Building Regulations Principal Designer is the designer responsible for planning, managing, monitoring and coordinating matters relating to the design work on a project so that Building Regulations compliance is properly addressed.
In simple terms, this person or organisation sits at the centre of the design team. They are not expected to personally design every beam, drainage run, fire precaution or insulation detail. However, they do need enough competence and authority to coordinate the designers who are responsible for those elements and to identify where compliance information is missing or inconsistent.
This dutyholder framework forms part of the changes made to the Building Regulations in England following the Building Safety Act reforms. The wider requirements came into force on 1 October 2023.
If you are still getting to grips with the overall approval system, our complete homeowner guide to the rules explains where design, construction and Building Control fit together.
When is a Building Regulations Principal Designer required?
This is where homeowners can easily become confused. For projects where more than one contractor is involved, or where it is reasonably foreseeable that more than one contractor will be involved, the regulations provide for a Principal Designer to take control of the design work and a Principal Contractor to take control of the building work.
A “contractor” does not simply mean the main builder. Depending on the contractual arrangements, a project might involve a builder alongside separate electricians, plumbers, roofers or other specialist trades.
Building Regulations Principal Designer requirement on a typical extension
Imagine you are building a rear extension. Your project could involve:
- an architectural designer preparing the plans,
- a structural engineer designing beams and foundations,
- a main building contractor,
- an electrician,
- a plumber or heating engineer, and
- specialist glazing or roofing contractors.
That is very different from a genuinely simple project involving one designer and one contractor. Therefore, it is sensible to establish the dutyholder arrangements early rather than waiting until the Building Control application or completion stage.
Our guide explaining how Building Control works in practice covers this distinction in more detail.
What does the Building Regulations Principal Designer role mean for a domestic homeowner?
A domestic client is broadly an individual having building work carried out on their own home, or the home of a family member, for purposes that are not connected with a business.
The rules recognise that ordinary homeowners are unlikely to be construction professionals. Therefore, the way the dutyholder arrangements operate for a domestic client is particularly important.
Where there are several designers and contractors, a homeowner can appoint a Principal Designer to control the design work and a Principal Contractor to control the building work.
However, if the domestic client does not expressly appoint them, the designer in control of the design phase becomes the Principal Designer, while the contractor in control of the construction phase becomes the Principal Contractor.
Before work progresses, it is also worth understanding the building control application process so the project team knows which drawings and supporting information will be needed.
Building Regulations Principal Designer duties explained
The Building Regulations Principal Designer role is much more than putting a name on an application form. The dutyholder must be actively involved with the design team and must have sufficient control and influence over design decisions.
1. Plan and manage design compliance
The Principal Designer needs arrangements for managing the design work so that relevant Building Regulations requirements are considered as the design develops.
Depending on the project, this could involve matters covered by Part A structure, Part B fire safety, Part F ventilation, Part H drainage, Part K protection from falling, Part L energy efficiency and other relevant Approved Documents.
2. Monitor the work of other designers
Different specialists often prepare different parts of a project. The Principal Designer therefore needs to take reasonable steps to make sure designers understand and fulfil their own duties.
For example, an architectural layout may need to coordinate with structural calculations, insulation specifications and drainage details. A change in one area can affect compliance elsewhere.
3. Coordinate design information
Coordination is one of the most important parts of the role. Information produced by different designers should fit together rather than creating contradictory instructions for the builder.
Good coordination also helps create a clearer package for Building Control. Our guide to the technical drawings normally used at this stage explains what this information can include.
4. Work with the Principal Contractor
Design work often continues after construction starts. Consequently, the Principal Designer and Principal Contractor need to communicate about changes, technical queries and any issue that could affect compliance.
5. Help the client manage information
The Principal Designer may also be asked to assist the client in providing relevant information to other dutyholders. Clear records become particularly important when designs change during construction.
Unsure who should coordinate your Building Regulations design?
We can review how your designer, structural engineer, builder and Building Control route fit together before the project moves too far.
Who appoints the Building Regulations Principal Designer?
On projects where the formal appointment requirement applies, the client is responsible for making the appropriate appointment. For a commercial client, that appointment should be made in writing.
Domestic clients are treated differently, as explained above. If a homeowner does not make a specific appointment, the designer who is in control of the design phase can become the Principal Designer by operation of the regulations.
When should a Building Regulations Principal Designer be appointed?
The sensible point is before significant Building Regulations design work is underway. Waiting until the plans have effectively been completed defeats much of the purpose of having someone coordinate compliance throughout the design process.
Early appointment gives the Principal Designer an opportunity to identify:
- which designers are required,
- which Building Regulations parts affect the project,
- where specialist calculations will be needed,
- how information will be coordinated, and
- who will deal with design changes during construction.
Who can be a Building Regulations Principal Designer?
There is no rule saying the Building Regulations Principal Designer must always be an architect. The role can be undertaken by an individual designer or an organisation, provided the relevant competence requirements are satisfied and they have control over the design work.
Depending on the project, that could potentially be an architectural practice, architectural technologist, engineer or another suitably competent designer.
What competence should a Principal Designer have?
The required competence needs to match the complexity of the project. Individuals are expected to have suitable skills, knowledge, experience and behaviours. Organisations must also have appropriate organisational capability.
Importantly, the Principal Designer does not need to be the technical expert in every discipline. However, they need enough understanding of Building Regulations and the project to assess the overall design process, challenge gaps and know when specialist advice is required.
PAS 8671 provides an industry framework for assessing competence for the Principal Designer dutyholder role. Nevertheless, following a competence standard does not remove the underlying legal responsibilities.
Building Regulations Principal Designer vs CDM Principal Designer
One of the most common sources of confusion is that UK construction law now uses the term Principal Designer in two related but different regulatory systems.
Building Regulations role
The focus is compliance of the design with the Building Regulations. The Principal Designer plans, manages, monitors and coordinates the design work so regulatory requirements are properly addressed.
CDM Principal Designer role
Under the Construction (Design and Management) Regulations 2015, the focus is health and safety during the pre-construction phase. The CDM Principal Designer manages and coordinates foreseeable health and safety risks arising from design work.
These are therefore different legal functions. However, the same individual or organisation can perform both roles where they have the necessary competence and control.
Building Regulations Principal Designer vs architect
An architect and a Principal Designer are not automatically the same thing.
“Architect” describes a protected professional title and a design profession. “Principal Designer”, in this context, describes a statutory project role and set of responsibilities.
An architect may be well placed to act as Principal Designer where they control the design work and have suitable competence. Equally, another suitably competent designer may be appointed instead.
Therefore, employing an architect does not mean you should simply assume the Principal Designer role has been accepted. The scope of appointment should make this clear.
What does a Building Regulations Principal Designer cost?
There is no statutory fixed fee for the Principal Designer role. The cost depends on how much coordination is required, how many designers are involved, the complexity of the project and whether the duty is already included within a wider architectural or technical design service.
For a straightforward domestic extension, the role may form part of an existing Building Regulations design package. On more complicated projects, additional coordination and compliance work may be quoted separately.
When comparing quotations, check the scope rather than looking only at the headline fee. In particular, confirm whether Principal Designer duties, design coordination and responses to Building Control queries are included.
Building Regulations Principal Designer checklist for homeowners
You do not need to become an expert in dutyholder legislation. However, asking a few questions at the start can prevent confusion later.
Step-by-step: check your Principal Designer arrangements
- List everyone likely to work on the project. Include the architectural designer, structural engineer, main builder and separately appointed specialist contractors.
- Ask who controls the design phase. That person or organisation is likely to be central to the Building Regulations Principal Designer role.
- Confirm the appointment and scope. Ask whether the designer is accepting the Building Regulations Principal Designer duties and, where appropriate, make the arrangement clear in writing.
- Check competence. The designer should have experience appropriate to the type and complexity of work you are undertaking.
- Confirm who is coordinating specialist designs. Structural calculations, drainage, ventilation, fire safety and energy performance information may all need to work together.
- Agree how design changes will be handled. Changes made on site can affect Building Regulations compliance and should be fed back into the design process.
- Keep the final compliance documents. Store approved drawings, calculations, certificates and completion information safely for future sale, remortgage or alterations.
You can read more about what happens during the approval route and the documents worth keeping when the project is finished.
Common Building Regulations Principal Designer mistakes
Most problems are caused by unclear responsibility rather than homeowners deliberately doing anything wrong.
- Assuming the architect automatically has the role. Check the appointment and scope.
- Confusing Building Regulations with CDM. The two Principal Designer functions have different purposes.
- Leaving the discussion until construction starts. The role is primarily about coordinating design compliance, so early involvement matters.
- Using someone without appropriate competence. The person needs sufficient knowledge and experience for the particular project.
- Failing to coordinate later design changes. A beam size, layout, insulation build-up or fire-safety alteration can have knock-on effects elsewhere.
- Assuming Building Control takes responsibility for compliance. Approval or inspection does not remove the duties placed on clients, designers and contractors.
For extensions in particular, our guide explaining what Building Control is likely to examine during the build is a useful next read.
FAQs: Building Regulations Principal Designer
When is a Building Regulations Principal Designer required?
Where a project involves, or it is reasonably foreseeable that it will involve, more than one contractor, the Building Regulations dutyholder arrangements provide for a Principal Designer to control the design work and a Principal Contractor to control the building work. Domestic clients have special provisions: if they do not make an express appointment, the designer in control of the design phase can become the Principal Designer.
What does a Building Regulations Principal Designer do?
The Principal Designer plans, manages, monitors and coordinates design work in relation to Building Regulations compliance. They take reasonable steps to make sure designers fulfil their duties, coordinate their work and produce designs which, if followed correctly, meet the relevant regulatory requirements.
What are the main Building Regulations Principal Designer duties?
Key duties include managing and coordinating design compliance, monitoring the work of designers, encouraging cooperation between the project team, liaising with the Principal Contractor and assisting the client with relevant information where required.
Who appoints the Building Regulations Principal Designer?
The client normally makes the relevant appointment. For a domestic homeowner, however, the regulations include default arrangements. If the homeowner does not specifically appoint a Principal Designer, the designer in control of the design phase can take on that role.
When should the Building Regulations Principal Designer be appointed?
Ideally, the role should be established before substantial Building Regulations design work begins. Early involvement allows the Principal Designer to coordinate designers and identify compliance issues while changes are still straightforward to make.
Who can be a Building Regulations Principal Designer?
The role can be undertaken by a suitably competent designer or design organisation with control over the design work. It is not limited to architects. Depending on the project, an architectural practice, architectural technologist, engineer or another suitably competent designer may be able to fulfil the role.
Does the Building Regulations Principal Designer have to be an architect?
No. Being an architect and acting as Principal Designer are different things. An architect can perform the role where they have the required competence and control, but the regulations do not reserve the role exclusively for architects.
What is the difference between a Building Regulations Principal Designer and a CDM Principal Designer?
The Building Regulations role focuses on coordinating design work for compliance with Building Regulations. The CDM 2015 role focuses on managing health and safety risks during the pre-construction phase. One suitably competent person or organisation may carry out both roles, but the appointments and responsibilities should be clearly understood.
Can the same person be the CDM and Building Regulations Principal Designer?
Yes, provided that person or organisation is suitably competent for both roles and has the necessary control over the work. Where the same party is intended to perform both functions, the appointment should make that clear rather than relying on assumptions.
When was the Building Regulations Principal Designer role introduced?
The wider dutyholder and competence changes were introduced through the Building Regulations reforms that came into force in England on 1 October 2023. They formed part of the broader building safety reforms following the Building Safety Act 2022.
Does every small domestic building project need a separate Principal Designer consultant?
No. The existence of the dutyholder role does not necessarily mean you need to employ an additional standalone consultant. On domestic projects the designer already controlling the design work may fulfil the role, provided the legal arrangements and competence requirements are satisfied.
What is a Building Regulations Principal Designer declaration?
Dutyholder information and declarations can form part of the Building Control process, particularly at completion and under the more stringent regime for higher-risk buildings. The exact documents required depend on the type of project and Building Control route, so homeowners should confirm the requirements with their Building Control body and project team.
Still unclear who should take responsibility?
Tell us about your project and the people already involved, and we can help you understand the likely design, Building Control and dutyholder arrangements.
Next steps & useful guides
If you are preparing a home alteration, extension or conversion, these related PME guides will help you understand the wider compliance process:
- Start with our complete homeowner overview of the rules – the Pillar guide supporting this article.
- Understand who checks the work and how inspections operate.
- See how the application stage works.
- Find out what technical drawings normally need to show.
- Understand the route from submission to approval.
- See what compliance means specifically for a house extension.
- Check which certificates and records you should retain.
- Main purpose To plan, manage, monitor and coordinate design work so Building Regulations compliance is properly addressed.
- Introduced The wider Building Regulations dutyholder regime came into force in England on 1 October 2023.
- Typical trigger Projects involving, or reasonably expected to involve, more than one contractor require particular attention to Principal Designer and Principal Contractor dutyholder arrangements.
- Domestic homeowners If the homeowner does not expressly appoint a Principal Designer, the designer in control of the design phase can become the Principal Designer.
- Who can do it? A competent designer or design organisation with appropriate control over the design work. It does not have to be an architect.
- Competence The role requires suitable skills, knowledge, experience and behaviours, together with organisational capability where an organisation is appointed.
- Building Regs vs CDM Building Regulations focuses on regulatory design compliance; CDM focuses primarily on managing health and safety risks associated with design and construction.
- Can one person do both? Yes, where they are competent for both roles and the appointment makes the responsibilities clear.
Not sure how the dutyholder rules apply to your extension or conversion? Ask Plans Made Easy to review your project arrangements.
Official guidance and further reading
Building safety legislation is detailed, so it is sensible to check current official guidance alongside any general homeowner article.
- GOV.UK – duties and competence requirements for design and building work
- UK legislation – Building Regulations etc. (Amendment) (England) Regulations 2023
- Health and Safety Executive – CDM Principal Designer roles and responsibilities
- British Standards Institution – PAS 8671 Principal Designer competence framework
Do you need to do anything about your Building Regulations Principal Designer?
For most homeowners, the key action is not to panic or assume that a whole new professional must suddenly be added to the project. Instead, establish who is actually controlling and coordinating the design work.
If your architect, architectural technologist or other lead designer is already coordinating the Building Regulations information, ask whether their appointment includes the Principal Designer dutyholder role. Then confirm who will act as Principal Contractor once construction begins.
Getting those responsibilities clear early helps your architect or designer, engineer, builder and Building Control body work from consistent information. More importantly, it reduces the risk of compliance issues only coming to light after work has already been built.
Plans Made Easy can help homeowners understand the drawings, Building Regulations application and coordination needed for extensions, loft conversions, garage conversions and other residential projects. Where specialist input is required, we can also help make sure the right information is identified before it becomes an expensive site problem.
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