CDM 2015 Core · Mandatory · Pre-Construction

Designer Appointment Letter

The designer appointment letter confirms the formal engagement of a designer under CDM 2015, ensuring they understand their duties to eliminate, reduce, and control foreseeable risks. It sets out the scope of design work, coordination requirements, and the obligation to provide information for the health and safety file.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. CDM 2015 Reg 5 remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

Legal basis	CDM 2015 Regulation 9 — designer duties apply to every designer on every project
CDM Reg 9 duties apply	On every construction project, regardless of size, duration, or notifiability
Written appointment	Not explicitly mandated by CDM 2015 (unlike PD/PC) — but required by professional body standards and best practice
Competence check	CDM 2015 Reg 8(3) — anyone appointing a designer must take reasonable steps to check competence
Designer duty not to start	CDM 2015 Reg 9(1) — designer must not start work unless satisfied the client is aware of their CDM duties
Who counts as a designer	Very broad — architects, engineers, QSs, interior designers, temp works engineers, contractors who specify/design, clients who specify products
Enforcing authority	Health and Safety Executive (HSE)

1. What Is a Designer Appointment Letter?

A Designer Appointment Letter is the written agreement by which a client or principal designer formally engages a designer to carry out design work on a construction project — including explicit acknowledgement of the designer's duties under CDM 2015 Regulation 9.

Unlike the Principal Designer and Principal Contractor appointments, CDM 2015 does not explicitly require a designer appointment to be in writing. However, professional body standards — including those of the RIBA, ICE, IStructE, and CIAT — require written terms of engagement for all commissions. In practice, a written appointment is the only defensible way to confirm the designer's scope, confirm their CDM duties have been communicated, and evidence the competence check required under Regulation 8(3). The CDM duties under Regulation 9 apply to every designer on every project regardless of whether a written appointment exists.

The key distinction from PD and PC appointments

CDM 2015 Regulation 5(1) explicitly requires the Principal Designer and Principal Contractor appointments to be ‘in writing.’ No equivalent provision exists for individual designer appointments. This means the absence of a written letter does not remove the designer's CDM duties — Regulation 9 applies regardless. However, it also means there is no formal record of what the designer was asked to do, what competence check was carried out, or when the designer confirmed the client's awareness of their duties. A written appointment letter closes these gaps.

2. Who Is a Designer Under CDM 2015?

The CDM 2015 definition of ‘designer’ is deliberately broad. It covers anyone who prepares or modifies a design, or who arranges for or instructs another person to do so. It is a functional definition — what matters is the activity being carried out, not the person's job title, professional registration, or contractual role.

“A designer is an organisation or individual whose business involves preparing or modifying designs for construction projects, or arranging for, or instructing, others to do this. Designs include drawings, design details, specifications, bills of quantity and design calculations.”— CDM 2015 Regulation 2 and HSE L153

Category	Examples
Obvious designers	Architects, structural engineers, civil engineers, building services engineers, interior designers
Less obvious but still designers	Quantity surveyors who specify materials, landscape architects, temporary works engineers, lighting designers, acoustic consultants who specify construction details
Contractors acting as designers	Any contractor who designs or specifies elements of the works — e.g. a steelwork subcontractor designing connections, a cladding installer specifying fixing systems, a groundworker designing temporary shoring
Clients acting as designers	A client who specifies a particular product, material, or construction method — e.g. insisting on a specific cladding system, specifying a paint product, or requiring a particular structural layout
Not CDM designers	Someone who only manufactures a product to a third-party specification without any design input; someone providing purely administrative support with no design decisions

Contractors and clients can be designers

This is one of the most commonly misunderstood aspects of CDM 2015. A contractor who specifies how an element is to be built — or a client who insists on a particular product or layout — is carrying out a design function and therefore holds designer duties under Regulation 9. The duty follows the activity, not the job title. If you are making decisions that affect what is built or how it is built, you are a designer.

3. What Are a Designer's CDM Duties?

CDM 2015 Regulation 9 sets out four distinct obligations that apply to every designer on every project. These duties cannot be contracted out of, and they apply regardless of the size, value, or complexity of the project.

“A designer must not commence work in relation to a project unless satisfied that the client is aware of the duties owed by the client under these Regulations.”— CDM 2015 Regulation 9(1)

This is a gate duty — the designer must check that the client understands their CDM responsibilities before starting any design work. It does not require the designer to educate the client in detail, but they must satisfy themselves that the client is aware. A written record of this check in the appointment letter is the most practical way to evidence compliance.

Regulation 9(2) and 9(3) set out the core design duty — the ERIC hierarchy:

Letter	Principle	Description
E	ELIMINATE	So far as is reasonably practicable, eliminate foreseeable risks to the health and safety of any person carrying out or affected by construction work, or maintaining or using the building as a workplace once built.
R	REDUCE	Where elimination is not reasonably practicable, take design measures to reduce risks to an acceptable level — for example, specifying edge protection rather than relying on harnesses, or designing for ground-level assembly rather than work at height.
I	INFORM	Provide information about any significant residual risks that remain in the design, so that other designers, contractors, and the principal designer can take them into account when planning their work.
C	CONTROL	Ensure that the design includes adequate information about control measures needed for remaining risks — for example, specifying a safe system of work for installing a complex structural element.

Regulation 9(4) adds a fourth obligation:

The designer must take all reasonable steps to provide, with the design, sufficient information about aspects of the design or materials used that could create foreseeable risks to health and safety during construction, maintenance, or use. This is the duty that requires designers to produce design risk information — commonly captured in a Designer Risk Register or Designer Risk Assessment — and provide it to the principal designer for coordination.

What counts as a ‘significant residual risk’ for Regulation 9(3)?

A significant residual risk is one that is not obvious to a competent contractor, or that is unusual or difficult to manage. The HSE guidance (L153) is clear that designers do not need to flag normal construction risks that a competent contractor would already manage as part of their standard site safety arrangements. The test is whether the risk is specific to this particular design and would not be apparent without being told. Examples include unusual loading conditions, non-obvious fragile materials, hidden voids, or construction sequences that must follow a specific order for structural stability.

4. What Should the Appointment Letter Contain?

While CDM 2015 does not prescribe a mandatory format for designer appointment letters, a properly drafted letter should cover the following elements to evidence compliance, establish clear scope, and protect both parties.

Element	Detail	Status
Project identification	Project name, address, and brief description of the works	Essential
Client details	Full name and registered address of the client or client representative	Essential
Designer details	Full name, registered address, and professional registrations of the appointed designer	Essential
Scope of design services	Clear description of what design work the designer is engaged to carry out — including RIBA stages or equivalent	Essential
CDM role confirmation	Explicit confirmation that the appointee will act as a CDM designer under Regulation 9	Essential
Competence evidence	Record of the competence check carried out under Regulation 8(3) — skills, knowledge, experience, and organisational capability	Essential
Client duty awareness	Confirmation that the designer is satisfied the client is aware of their CDM duties (Regulation 9(1))	Essential
ERIC hierarchy acknowledgement	Acknowledgement that the designer will apply the eliminate-reduce-inform-control hierarchy in their design work	Recommended
Design risk information	Obligation to provide design risk information (significant residual risks) to the principal designer or other designers	Essential
Cooperation and coordination	Commitment to cooperate with the principal designer and other designers on the project	Recommended
Duration and termination	Start date, anticipated end date or stage, and arrangements for early termination	Recommended
Professional indemnity insurance	Confirmation of appropriate PII cover — typically required by professional body standards	Recommended
Fee basis	Fixed fee, hourly rate, or percentage basis — including what is and is not included	Recommended
Signatures	Signed and dated by both parties — the client (or their authorised representative) and the designer	Essential

The level of detail should be proportionate to the project. A single-discipline designer engaged on a straightforward domestic extension does not need a 20-page appointment document. But the core CDM elements — scope, competence, client awareness, and design risk obligations — should always be addressed, however briefly.

5. Designer Duties and the PCIP

The designer's CDM duties do not operate in isolation. They are part of a wider information flow that connects the Pre-Construction Information Pack (PCIP), the designer's own design risk output, and the Construction Phase Plan. Understanding this flow is essential to discharging the duties properly.

Receiving information: The designer is entitled to receive the PCIP from the client before starting design work. This gives the designer the site-specific information they need to apply the ERIC hierarchy — you cannot eliminate or reduce construction risks if you do not know what hazards exist on site.
Applying the ERIC hierarchy: Using the PCIP and their own professional knowledge, the designer applies eliminate-reduce-inform-control to every aspect of their design. The output is a design that has been developed with health and safety in mind.
Providing design risk information: Under Regulation 9(3) and 9(4), the designer must provide information about significant residual risks to the principal designer (or directly to contractors on single-designer projects). This is typically captured in a Designer Risk Register.
Contributing to the H&S File: Design information that is relevant to the future maintenance, cleaning, or alteration of the building must be provided to the principal designer for inclusion in the Health and Safety File.

The appointment letter should make these information flows explicit — confirming that the designer will receive the PCIP, will provide design risk information in a timely manner, and will cooperate with the principal designer on coordination of health and safety matters across the design team.

6. Common Mistakes

Assuming the design fee agreement covers CDM duties

A standard professional services agreement or fee letter does not constitute a CDM designer appointment. It may define scope, fees, and contractual obligations — but it will not typically address Regulation 9 duties, the ERIC hierarchy, design risk information requirements, or the Regulation 9(1) client awareness check. CDM duties must be addressed separately or explicitly within the appointment.

No competence check on record

CDM 2015 Regulation 8(3) requires anyone appointing a designer to take reasonable steps to satisfy themselves that the designer has the skills, knowledge, experience, and (if an organisation) organisational capability to carry out the role. If there is no written record of this check, there is no evidence it was done. The appointment letter is the natural place to record it.

Failing to confirm client awareness before starting work

Regulation 9(1) is a hard gate — the designer must not commence work until satisfied the client is aware of their duties. In practice, many designers begin work immediately upon receiving instructions without any CDM conversation. The appointment letter should include an explicit confirmation that this check has been carried out.

Not providing design risk information to the principal designer

The duty under Regulation 9(3) and 9(4) to provide information about significant residual risks is frequently overlooked, particularly by smaller practices. The appointment letter should clearly state this obligation so neither party can later claim it was not understood.

Confusing the designer role with the Principal Designer role

These are separate CDM roles with different duties. Every project has at least one designer. Only projects with more than one contractor require a Principal Designer. A designer who is not the Principal Designer does not have PD coordination duties — but they still have full Regulation 9 obligations.

No written appointment at all

While CDM 2015 does not explicitly require a written designer appointment (unlike PD/PC), proceeding without one leaves no record of scope, competence, CDM duties, or client awareness. In the event of an HSE investigation or dispute, the absence of a written appointment is a significant evidential gap.

7. How It Relates to Other Documents

The Designer Appointment Letter sits within a wider set of CDM documents. Understanding the connections prevents overlap, gaps, and confusion about which document covers what.

Document	Relationship to the Designer Appointment Letter
Principal Designer Appointment Letter	The PD appointment is a separate CDM role with its own written appointment requirement. The PD coordinates health and safety across the design team; individual designers cooperate with and report design risk information to the PD.
Principal Contractor Appointment Letter	The PC appointment is similarly separate. The designer provides design risk information that feeds into the PC's Construction Phase Plan. There is no direct contractual relationship created by CDM, but an information flow exists.
Pre-Construction Information Pack (PCIP)	The PCIP is the input the designer needs to apply the ERIC hierarchy. The designer should receive it before starting work and should use it to identify site-specific risks relevant to their design decisions.
Designer Risk Register	The Designer Risk Register is the output of the designer's Regulation 9 duties. It captures the significant residual risks that the designer has been unable to eliminate or reduce through design, and must be provided to the PD.
Health and Safety File	The designer contributes information to the H&S File — particularly design information relevant to future maintenance, cleaning, repair, or alteration of the completed building.

8. Frequently Asked Questions

Is a written designer appointment letter legally required under CDM 2015?▾

No — unlike the Principal Designer and Principal Contractor appointments, CDM 2015 does not explicitly require a designer appointment to be in writing. However, professional body standards require written terms of engagement, and a written appointment is the only practical way to evidence the competence check (Reg 8) and client awareness confirmation (Reg 9(1)). Best practice makes it effectively essential.

Does every designer on a project need a separate appointment letter?▾

Each designer engaged on a project should have their own appointment confirming their scope, CDM duties, and competence. On larger projects with multiple designers, this is critical for avoiding gaps in responsibility. On smaller projects where one organisation provides all design services, a single appointment may cover all design disciplines within that organisation.

What is the difference between a designer and a Principal Designer?▾

A designer is anyone who prepares or modifies a design for a construction project — Regulation 9 duties apply. A Principal Designer is a specific CDM role required on projects with more than one contractor, appointed in writing by the client to coordinate health and safety during the pre-construction phase. A designer can also be the PD, but the roles and duties are distinct.

Can a contractor be a designer?▾

Yes. Any contractor who designs, specifies, or selects products or construction methods is carrying out a design function and holds designer duties under Regulation 9. This includes design-and-build contractors, specialist subcontractors who design their own elements, and any contractor who modifies a design on site.

What happens if the designer does not check client awareness before starting work?▾

The designer is in breach of Regulation 9(1). This is a criminal offence. In practice, HSE enforcement in this area typically arises after an incident, when the investigation examines whether all CDM duties were discharged. The absence of any record that the check was carried out will be treated as evidence that it was not done.

Does the appointment letter need to reference the ERIC hierarchy specifically?▾

CDM 2015 does not prescribe the content of a designer appointment letter. However, including an explicit reference to the ERIC hierarchy (eliminate, reduce, inform, control) ensures both parties understand the designer's core obligation under Regulation 9(2). It also provides evidence that the duty was communicated, which is valuable in the event of a dispute or investigation.

Who checks the designer's competence?▾

CDM 2015 Regulation 8(3) places this duty on whoever appoints the designer — typically the client, but it can also be the principal designer or another organisation commissioning design work. The check must assess skills, knowledge, experience, and (for organisations) organisational capability. It does not require formal assessment — reasonable steps are sufficient.

Generate your Designer Appointment Letter on Construction Suite

Construction Suite walks you through every required section with a guided Q&A — built to CDM 2015 Reg 5 — and generates a professionally formatted document in minutes.

Get started free