Do CDM principal designers need professional indemnity insurance?

Reviewed by Matthew Bartlett, Director, Apex Insurance Brokers Limited · Last reviewed 2026-08-05

The principal designer duty holder under the Construction (Design and Management) Regulations 2015 (CDM 2015) plans, manages and coordinates health and safety during the pre-construction phase of a project. Whether that role sits with an architect, a CDM consultant, an engineer or a dedicated health-and-safety professional, it is a professional service for which you can be held liable if your advice or coordination falls short. That liability is what PI insurance responds to.

Is PI a legal requirement for principal designers?

No single UK law says "a CDM principal designer must hold PI insurance". CDM 2015 imposes duties, not an insurance mandate. Unlike compulsory covers such as employers' liability under the Employers' Liability (Compulsory Insurance) Act 1969, PI for principal designers is not required by statute.

That distinction matters far less than it sounds. The requirement almost always arrives through three routes instead: your contract, your professional body, and the plain commercial reality of carrying advice risk. Meet any one of those and the answer becomes a firm yes.

Where the requirement actually comes from

1. Your client contract and appointment

This is the most common driver. Professional appointments — whether on a bespoke deed or a standard form such as an RIBA or ACE appointment — typically require the consultant to hold PI insurance to a specified limit for the duration of the appointment, and often for a set period afterwards. Public-sector clients and large developers almost always specify a limit before they will sign. If your appointment names a figure, that figure is contractually binding on you.

2. Professional membership bodies

If you are a chartered or registered professional carrying out the principal designer role, your body's rules bite. Architects registered with the Architects Registration Board (ARB) and members of the Royal Institute of British Architects (RIBA) are subject to codes that require adequate and appropriate PI cover. The same expectation applies to members of the Institution of Civil Engineers (ICE), the Royal Institution of Chartered Surveyors (RICS), and the Chartered Institute of Building (CIOB). Members of the Association for Project Safety (APS), the body most associated with CDM and principal designer competence, likewise operate to standards that assume you are properly insured. Check your own body's current rules — the practical answer for a chartered practitioner is that PI is expected.

3. The advice and coordination risk you carry

Even absent a contract clause or a body's rule, the principal designer role is exactly the kind of work PI is built for. You are giving professional judgement on how design decisions affect health and safety, coordinating information between designers, and helping the client discharge their CDM duties. If a foreseeable risk is missed, if pre-construction information is inadequate, or if your advice is later argued to have contributed to a loss, a claim can follow — and defending it costs money whether or not you were ultimately at fault. PI covers your legal defence costs as well as damages awarded against you.

How much cover should a principal designer hold?

There is no universal figure. The right limit is driven by the size and risk profile of the projects you take on and, above all, by what your appointments require. Common commercial limits offered are £1m, £2m and £5m of indemnity, but a limit is only "enough" if it meets every contract you are working under — take on a project that specifies £5m while you carry £2m and you are in breach.

• Match your limit to the highest limit demanded across your live appointments, not the average.
• Check whether cover is written on an aggregate or each-and-every-claim basis — contracts sometimes specify one.
• PI is usually written on a claims-made basis, so you need cover in force when a claim is notified, not just when the work was done — this is why run-off cover matters if you stop trading.
• Confirm the policy wording actually contemplates CDM / principal designer duties rather than excluding them.

Because the role can attract exclusions or specific conditions, it is worth having a broker who understands construction and CDM read the wording against your appointments. If you would like that reviewed, start a quote with Apex and we will check the fit.

When might you genuinely not need it?

The honest exception is narrow. If you are not undertaking any paid principal designer or design service — for example, a domestic client who is not carrying out the role commercially — there is no professional exposure to insure. But if you are appointed as principal designer for a fee, in any commercial or public project, you should assume PI is needed and confirm the exact limit from your appointment before work starts.

Common questions

Is professional indemnity the same as public liability?
No. Public liability covers injury to third parties or damage to their property. PI covers financial loss caused by your professional advice, design or coordination. A principal designer typically needs both, but they respond to different claims.

Does my architecture practice's existing PI already cover the principal designer role?
Often yes, but do not assume it. Check that your current wording and limit extend to CDM principal designer duties and meet the limits your appointments specify. A broker can confirm the coverage is not excluded.

What happens to cover after a project finishes?
Because PI is claims-made, a claim can arrive years after completion. You need cover in force at the time of notification, which is why practitioners maintain PI continuously and arrange run-off cover if they cease trading.

Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (FRN 724952). This guide is general information, not advice on a specific policy or a substitute for your policy wording.