Building regulations dutyholders explained: Who Does What?

If you feel unsure about who carries which legal responsibilities on a building project, you are not alone. Since October 2023, the Building Regulations framework in England formally assigns clear “dutyholder” responsibilities across the client, designers, contractors, and the principal designer and principal contractor roles. This article gives you building regulations dutyholders explained in practical terms, so you can set up your project correctly, avoid gaps, and create evidence that building control expects to see.

What “dutyholders” means under the Building Regulations

The Building Regulations use “dutyholder” to mean the people and organisations who plan, manage, coordinate, and deliver compliant design and compliant building work. In England, Part 2A of the Building Regulations 2010 sets out those roles, their duties, and competence expectations. It defines key project roles including “client”, “designer”, “contractor”, “principal designer”, and “principal contractor”, and it also adds the dutyholder duties themselves.

You should treat these duties as operational requirements, not paperwork. You can win or lose compliance outcomes based on whether you:

appoint the right roles at the right time

choose competent people and keep records of your checks

coordinate design and construction decisions so they do not undermine compliance

maintain a clean information trail from early design through completion

When dutyholder duties apply and who counts as a dutyholder

Dutyholder duties apply to projects that include building work under the Regulations. “Building work” includes new builds, extensions, certain service installations, material alterations, and material changes of use.

The core dutyholders are:

Client

Designers

Contractors

Principal designer

Principal contractor

The principal roles trigger when more than one contractor will work on the project, or when that situation is reasonably foreseeable. The client must appoint a principal designer and principal contractor in writing, with timing rules that tighten further for higher-risk building work.

Building Regulations Dutyholders Explained: the “who does what” Summary

Use this as a quick checklist for dutyholders:

The client sets up the project for compliance: resources, time, appointments, and information.

Designers make compliant designs and provide enough information for others to build compliantly.

Contractors build in line with compliant designs and manage site delivery so work stays compliant.

The principal designer coordinates design work so the overall design remains compliant.

The principal contractor coordinates construction so the overall build remains compliant.

The client’s duties: your compliance system starts here

Regulation 11A places a direct duty on the client to make suitable arrangements for planning, managing, and monitoring the project so it complies with all relevant requirements. That includes providing sufficient time and resources.

Your arrangements should achieve four things:

1) You drive compliant design

You must ensure design work produces a design that would comply if built.

Practical actions you should take:

define the building regulations scope early (parts A to S, as relevant)

run a design compliance plan with milestones, reviews, and sign-offs

agree who owns each Part (for example, fire strategy ownership, energy model ownership, drainage strategy ownership)

2) You drive compliant construction delivery

You must ensure building work follows the relevant requirements.

Practical actions:

require inspection and test plans linked to each regulated element

set “hold points” before covering up works (structure, fire stopping, airtightness layers, drainage)

require product approval rules (no substitutions without sign-off)

3) You enable cooperation

The Regulations require cooperation between designers and contractors. Your job is to structure contracts, meetings, and information flows so cooperation happens routinely, not only when something goes wrong.

4) You keep reviewing whether work becomes higher-risk building work

Regulation 11A requires periodic review to identify whether work is higher-risk building work. Regulation 11B adds specific information-arrangement duties for projects that include higher-risk building work, including making sure designers and contractors know the project includes HRB work and what that means.

Domestic clients: duties do not disappear, they shift

Where the client is a domestic client, the Regulations allocate certain client duties to others. For example, key duties under 11A(1) to (3) get carried out by the contractor, or the principal contractor, or in some cases the principal designer if agreed in writing. If a domestic client fails to appoint the principal roles, the “designer in control of the design phase” becomes principal designer and the “contractor in control of the construction phase” becomes principal contractor.

If you work with domestic clients, you should:

document who acts as principal designer and principal contractor from the start

explain in plain language how decisions affect compliance

keep your own records, because you often inherit duties by default

Building regulations dutyholders explained for appointments: principal designer and principal contractor

Regulation 11D sets the appointment trigger and the timing:

if more than one contractor will work on the project, or that is foreseeable, the client must appoint in writing a principal designer and principal contractor

for HRB work requiring an application to the regulator, make the appointment before submitting that application

for other projects, appoint before the construction phase begins

If an appointment ends, the client must appoint a replacement as soon as reasonably practicable. If the client fails to appoint, the client must fulfil those principal duties until they appoint someone.

Practical appointment checklist you can use:

confirm whether multiple contractors will work on the project (including specialist subcontractors)

appoint principal designer and principal contractor in writing

set clear “control” definitions: who controls the design work, who controls the building work

define handover expectations at appointment end (the Regulations require an arrangements document within 28 days for principal roles when they step down)

Competence: you must choose capable people and prove you checked

Part 2A does not let you appoint anyone and hope for the best. Regulation 11E requires reasonable steps before permitting someone to carry out design or building work. You must satisfy yourself they meet general competence requirements. For HRB-related work, you must also ask about serious sanctions within the previous five years and consider misconduct information.

General competence requirements sit in regulation 11F:

individuals need the skills, knowledge, experience, and behaviours to do the work compliantly

organisations need organisational capability to do the work compliantly

designers and contractors also need the competence to fulfil their dutyholder duties, not only technical execution

Principal roles have additional competence requirements:

principal designer competence requirements in 11G

principal contractor competence requirements in 11H

What you should record to prove competence checks:

role-specific capability statement (past similar projects, staff competence, management systems)

named responsible person for each dutyholder function

evidence of training and supervision plans for anyone “in training” (allowed in general roles, not allowed for appointment as principal roles)

for HRB projects: written record that you asked about serious sanctions and considered relevant information

General duty to plan, manage, and monitor: it applies to everyone doing work

Regulation 11J sets a baseline duty:

anyone carrying out building work must plan, manage, and monitor it so it complies

anyone carrying out design work must plan, manage, and monitor it so that if built, it would comply

both groups must cooperate with the client and others to the extent necessary to ensure compliance

This is where projects often fail. Teams treat compliance as a final inspection issue. The Regulations treat compliance as a continuous management duty.

Designers’ duties: make compliance real, not aspirational

Regulation 11K adds designer-specific duties:

you must not start design work unless satisfied the client understands their duties

you must take reasonable steps to ensure the design would comply if built

you must provide sufficient design, construction, and maintenance information to help others comply

if you only design part of the work, you must consider related design work and report concerns to the principal designer

you must advise if asked on whether work is higher-risk building work

Practical designer controls that improve compliance outcomes:

create a compliance matrix by Building Regulations Part, with owners and evidence outputs

run “design freeze” rules for regulated elements (fire strategy, structure, Part L model inputs)

create an RFI process that forces documented resolution of compliance-critical questions

issue coordinated drawings and specifications with change logs

Contractors’ duties: build compliant work and control site changes

Regulation 11L puts duties on contractors:

you must not start building work unless satisfied the client understands their duties

you must ensure your work complies with all relevant requirements

you must supervise, instruct, and inform workers so their work stays compliant

you must provide sufficient information about the work to help others comply

if you only deliver part of the build, you must consider related work and report compliance concerns to the principal contractor

you must advise if asked whether work is higher-risk building work

Practical contractor controls that protect compliance:

set up a “no unapproved substitutions” rule for regulated products and assemblies

use installation check sheets for fire stopping, cavity barriers, airtightness layers, structural fixings

photograph evidence before closing up work, tied to location and drawing reference

run toolbox talks that focus on regulated details, not only health and safety

Principal designer duties: coordinate the design so it stays compliant

Regulation 11M sets principal designer duties. The principal designer must:

plan, manage, and monitor design work during the design phase

coordinate design matters so reasonable steps ensure the design would comply if built

ensure designers cooperate and coordinate design work so the overall design remains compliant

liaise with the principal contractor and share relevant information

consider comments from the principal contractor about compliance

assist the client with information provision if requested

provide an arrangements document to the client within 28 days after their appointment ends

if replaced, review prior arrangements and improve them so the design remains compliant

How you should run the principal designer role in practice:

create a “design compliance plan” with review gates (concept, developed, technical, pre-start)

chair design compliance reviews focused on the regulated risks: fire, structure, energy, ventilation, overheating, drainage, accessibility

build a single source of truth for the design: controlled document register, change control, approved detail library

formalise design risk items and how you close them (for example, cladding build-up classification, cavity barrier lines, structural movement joints, thermal bridging junctions)

Principal contractor duties: coordinate the build so it stays compliant

Regulation 11N sets principal contractor duties. The principal contractor must:

plan, manage, and monitor building work during the construction phase

coordinate building work so it complies with all relevant requirements

ensure contractors cooperate with the client, principal designer, and each other

ensure contractors coordinate their work so the overall build remains compliant

liaise with the principal designer and share information relevant to design and build coordination

consider comments from the principal designer about compliance

assist the client with information provision if requested

provide an arrangements document within 28 days after their appointment ends

if replaced, review prior arrangements and improve them so work remains compliant

Practical principal contractor controls:

implement a construction compliance plan aligned to the design compliance plan

link programme activities to regulated inspections and evidence capture

enforce method statements for compliance-critical installs

manage interfaces aggressively (M&E penetrations through fire compartments, façade brackets and insulation continuity, drainage falls and ventilation terminations)

How dutyholders should work together across the project lifecycle

To make building regulations dutyholders explained genuinely useful, you need a repeatable workflow you can run on every project.

Stage 1: Brief and appointments

Client:

decide early if multiple contractors will work on the project

appoint principal designer and principal contractor in writing where required

issue a building regulations responsibility matrix

Principal designer:

confirm what information you need from the client and designers

set your design coordination plan and meeting cadence

Stage 2: Design development

Designers:

develop compliance evidence as part of design, not after

coordinate assumptions that drive Part L, Part F, and Part O decisions

Principal designer:

run compliance reviews and track actions to closure

check design packages for coordination, not just completeness

Stage 3: Pre-construction

Principal contractor:

review design intent against buildability and compliance risk

build inspection and test plans tied to the programme

Principal designer:

respond to buildability comments without diluting compliance

lock down critical details and approved products where possible

Stage 4: Construction delivery

Contractors:

supervise installs and record evidence before closing up

report compliance concerns immediately, with a clear proposed solution

Principal contractor:

coordinate sequencing and interfaces

maintain evidence files so you can support completion certification routes

Stage 5: Completion and handover

All dutyholders:

close open compliance actions

compile final evidence: commissioning, test certificates, photos, as-builts, O&M information

ensure the client can operate and maintain the building in a compliant state, supported by the “sufficient information” duties in design and build roles

Common mistakes that create enforcement risk

1) Late principal appointments
If you appoint principal roles after design decisions harden, you lose the coordination value and you increase rework.

2) Confusing CDM and Building Regulations principal roles
They can align, but you still need clarity about Building Regulations compliance coordination and evidence.

3) No proof of competence checks
Regulation 11E expects records of reasonable steps. You should keep them on file.

4) Uncontrolled product substitutions
Most serious failures come from “equivalent” swaps that break fire, structure, thermal, or moisture performance.

5) Gaps at interfaces
You should treat interfaces as owned items with named leads and signed details.

Conclusion: Building Regulations Dutyholders Explained

You reduce compliance risk when you treat dutyholder duties as your operating system for the project. You should appoint principal roles early, check competence in a documented way, coordinate design decisions before site changes force compromises, and keep a clean evidence trail from concept to completion. If you want building regulations dutyholders explained in a way that stands up under building control scrutiny, build these duties into your contracts, meeting rhythm, and document control.

FAQs: building regulations dutyholders explained

1) Who is the “client” under the Building Regulations?

The client is the person for whom a project is carried out. The Regulations define “client” and place planning, managing, monitoring, and information duties on them.

2) When must you appoint a principal designer and principal contractor?

You must appoint them in writing when more than one contractor will work on the project, or that is reasonably foreseeable. For non-HRB projects, you appoint before the construction phase begins. For HRB projects requiring an application to the regulator, you appoint before submitting that application.

3) What happens if the client does not appoint the principal roles?

The Regulations state the client must fulfil the duties of the principal designer or principal contractor until they appoint someone. For domestic clients, default allocation rules can also apply.

4) Do dutyholder duties apply to small projects?

Yes, dutyholder duties apply to projects that include building work. The scale changes how you implement controls, but the responsibilities do not disappear.

5) What does “competence” mean in this context?

Competence means individuals have the skills, knowledge, experience, and behaviours, and organisations have the organisational capability, to do the work compliantly and fulfil their dutyholder duties.

6) Can someone “in training” act as a dutyholder?

An individual in training can carry out work if you put supervision arrangements in place, but you cannot appoint someone in training as principal designer or principal contractor.

7) What is the principal designer responsible for under Building Regulations?

The principal designer plans, manages, and monitors design work and coordinates design matters so reasonable steps ensure the design would comply if built. They also ensure cooperation and coordination among designers and liaise with the principal contractor.

8) What is the principal contractor responsible for under Building Regulations?

The principal contractor plans, manages, and monitors building work during construction and coordinates contractors so the overall build complies. They liaise with the principal designer and manage cooperation between contractors.

9) Do designers and contractors have duties even without principal roles?

Yes. Designers and contractors have their own duties, including planning, managing, monitoring, cooperation, and providing sufficient information. The principal roles add coordination across multiple parties.

10) What records should you keep to show compliance with dutyholder duties?

You should keep written appointment records, competence check records, design coordination evidence, inspection and test plans, change control logs, evidence photos, certificates, commissioning records, and handover information. The Regulations also require principal roles to provide an arrangements document when their appointment ends.

11) Are Building Regulations dutyholder roles the same as CDM roles?

They can be carried out by the same people, and the Regulations allow a client to certify that the CDM principal designer or principal contractor is treated as appointed for Building Regulations purposes. You still need clarity on Building Regulations compliance coordination and evidence expectations.

12) What is the fastest way to reduce dutyholder risk on a live project?

Create a responsibilities matrix by Building Regulations Part, appoint missing principal roles in writing if required, implement change control for regulated elements, and start capturing evidence before works get covered up.

Contact

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