Who Is the Duty Holder? Legal Responsibility on UK Construction Projects, Explained

On every UK construction project, the law assigns specific people and organisations legal responsibility for safety and compliance. These are the duty holders — and getting their appointment, competence and record-keeping wrong is one of the most common ways a project runs into delay, dispute, or enforcement. This article explains who the duty holders are, how the rules have tightened since Grenfell, and what clients, developers and contractors should put in place before work begins.

A surprising number of construction problems trace back to a single unanswered question: who is actually responsible here? It sounds basic, but on a live project — with a client, a designer, a main contractor and a chain of subcontractors all in motion — responsibility can become blurred at exactly the points where clarity matters most.

UK law removes that ambiguity. It assigns defined legal roles, known as duty holders, to the parties who commission, design and build. A duty holder is not a job title someone chooses; it is a statutory responsibility that attaches to what you do on a project, whether you realise it or not. Understanding these roles is no longer optional knowledge for a developer, a landlord, or even a homeowner planning a serious renovation. Since the reforms that followed the Grenfell Tower fire, the consequences of getting it wrong have become significantly more serious.

What a Duty Holder Actually Is

A duty holder is a person or organisation that the law makes legally responsible for ensuring a building project is planned, designed, managed and carried out safely and in line with the regulations. The defining feature is that these duties cannot be contracted or delegated away. You can appoint competent people to discharge them, but the legal responsibility stays with the role.

In practice, two separate legal frameworks define who the duty holders are and what they must do:

• The Construction (Design and Management) Regulations 2015 (CDM 2015), which focus on the health and safety of workers and the public during construction. CDM applies to every project — from a domestic refurbishment to a major commercial build.
• The Building Safety Act 2022 and the associated dutyholder regime in the Building Regulations (in force from October 2023), which focus on whether the finished building actually complies — particularly for fire safety, structural integrity and energy performance. The core dutyholder responsibilities apply to all building work that needs building regulations approval, not only high-rise residential. (HSE: CDM 2015; GOV.UK: Building Safety Act)

These two regimes broadly use the same role titles, which is deliberate: the people managing site safety and the people responsible for regulatory compliance are usually the same parties, now carrying duties under both.

The Core Duty Holder Roles

Across both frameworks, responsibility is concentrated in a small number of named roles. The important point is that you do not get to opt out of having duty holders — they exist on your project whether or not anyone has been formally appointed.

It is possible for one organisation to hold more than one role, provided it genuinely has the competence and capacity to do so. What is not acceptable is for a role to sit vacant or unassigned.

What Homeowners and Domestic Clients Often Miss

If you are having work done on your own home — a kitchen, a loft conversion, an extension — you are technically a domestic client, and the law treats you gently. In most cases your client duties pass by default to the contractor (or, on a multi-contractor job, to the principal contractor or principal designer). That is sensible: a homeowner cannot reasonably be expected to manage construction safety.

But "your duties pass to the contractor" assumes there is a competent contractor properly taking them on. Problems often arise on single-trade or informal jobs where no one has clearly stepped into the duty holder role, and on larger domestic projects where the homeowner has engaged several trades directly without anyone coordinating them. At that point the homeowner can find themselves, in practice, acting as the de facto client without the support the role assumes. If you are running a substantial whole-home refurbishment or a loft conversion, it is worth confirming in writing who is holding which duties before work starts.

Higher-Risk Buildings: A Stricter, Harder Regime

For higher-risk buildings (HRBs) the rules step up considerably. An HRB is generally a building that is at least 18 metres tall, or has seven or more storeys, and contains at least two residential units. (GOV.UK: criteria for higher-risk buildings)

It is also worth knowing where the regulator stands today, because it has changed. On 27 January 2026 the Building Safety Regulator moved out of the Health and Safety Executive to become a standalone body sponsored by the Ministry of Housing, Communities and Local Government — the first step towards a single construction regulator recommended by the Grenfell Inquiry. The gateway approval process has been a well-documented source of programme delay. For anyone planning HRB work, the regulatory timeline is a real programme risk that needs building into the schedule from the outset, not assumed away.

A note on scope: the Building Safety Act dutyholder regime applies in England, and parallel reforms are being phased in across the devolved nations on their own timelines. CDM applies across Great Britain. If your project sits outside England, check the position locally.

Competence: The Duty You Cannot Fake

The single biggest shift in the post-Grenfell regime is that competence is now assessed, not assumed. Every duty holder must have the skills, knowledge, experience and behaviours their role demands, and — crucially — be able to evidence it. For principal designers and principal contractors, publicly available standards (the PAS 8670/8671/8672 suite) set out what good competence looks like.

For higher-risk work, the regulator can effectively assess whether an appointed principal designer or principal contractor is competent. If they are judged not to be, the project does not proceed. This has created genuine scarcity of demonstrably competent duty holders in parts of the market, and it changes the client's job: appointing the cheapest available name is now a liability, because the client is the one legally required to appoint competent people.

What Goes Wrong When Duty Holder Responsibilities Are Unclear

The failures are rarely dramatic at the point they happen. They are quiet gaps that become expensive later:

• No one clearly appointed. Work starts, an incident or inspection occurs, and it emerges that no competent party formally held the principal contractor or principal designer duties. The client is exposed.
• Competence that cannot be evidenced. The right people were involved, but nothing on file proves it. Under the current regime, if it is not documented, it is difficult to defend.
• Uncontrolled change. A design or specification changes on site, no one assesses or records the impact, and the building no longer matches what was approved — a problem that surfaces at completion, or worse, after handover.
• A weak or missing golden thread. Information is scattered across emails and individuals. When the regulator, an insurer, or a future owner asks how a safety-critical decision was made, the answer cannot be produced.

What Good Practice Looks Like

Strong projects treat duty holder responsibility as something to design in at the start, not audit at the end. From our experience, the difference shows up in a handful of habits:

None of this is bureaucracy for its own sake. Done well, it is what keeps a programme stable, a budget predictable, and a building defensible long after the scaffolding comes down.

Where Independent Oversight Helps

At Tarj Construction we work with developers, contractors and asset owners as an independent partner on exactly these questions — confirming that duty holder responsibilities are properly assigned, that compliance is evidenced rather than assumed, and that the documentation behind a project would stand up to a regulator, an insurer, or a future owner.

That is the focus of our Compliance & Building Safety Audits and our broader consultancy support for developers and contractors. For the underlying rules, our explainers on CDM 2015 and UK building regulations and safety legislation go a level deeper.

The Takeaway

"Who is the duty holder?" has become a gateway question for any serious project. It determines who carries legal responsibility for safety and compliance, and the answer needs to be clear, competent and documented before work begins — not reconstructed afterwards when something has gone wrong.

For a homeowner, that means confirming who is taking on your client duties. For a developer or contractor, it means appointing demonstrably competent people, controlling change, and keeping an evidence trail that proves the right decisions were made. The regime is stricter than it was, the regulator is evolving, and the cost of getting it wrong is real — but the underlying principle is simple and worth holding onto: on a construction project, responsibility should never be a question no one can answer.

Frequently Asked Questions

Do duty holder rules apply to a home extension?

Yes. CDM 2015 applies to all construction work, including domestic projects. However, the duties are lighter for a domestic client — in most cases they transfer to the contractor by default. The Building Regulations dutyholder regime also applies to any building work that requires building regulations approval, which most extensions do. The practical lesson for homeowners is to confirm who is taking on the relevant duties in writing before work begins, particularly if you are engaging multiple trades yourself.

Can one company be both principal designer and principal contractor?

Yes, provided the organisation genuinely has the competence and capacity to fulfil both roles. This is common on design-and-build contracts. Both roles carry distinct responsibilities under CDM 2015 and the Building Regulations dutyholder regime — particularly the separation between design-phase risk management and construction-phase site control — so the company must be able to demonstrate it can handle each effectively.

What counts as a higher-risk building?

During design and construction, a higher-risk building is generally one that is at least 18 metres in height or has at least seven storeys, and contains at least two residential units. The threshold also applies to certain care homes and hospitals. During the occupation phase, the definition is broadly the same. See the GOV.UK higher-risk building criteria for the current detail, which should be verified for any specific building.

Who is the duty holder once people move in?

Once residents occupy a higher-risk building, responsibility passes to the Accountable Person — typically the building owner or management company. Where there are multiple accountable persons, one becomes the Principal Accountable Person. They must register the building with the Building Safety Regulator, prepare a safety case, apply for a building assessment certificate, and operate a system for residents to raise safety concerns. For standard buildings, the building owner continues to carry responsibilities under existing health and safety and fire safety law.