There are now two Principal Designer roles in UK construction — one under CDM 2015 and one under the Building Safety Act — and a single firm sitting in both for the same project carries a dual statutory exposure that the PI market has only recently learned to underwrite.
The Construction (Design and Management) Regulations 2015 created the original Principal Designer role: a planning-and-coordination duty focused on health and safety in the design phase, applicable to any project with more than one contractor. The Building Safety Act 2022 and its supporting Higher-Risk Buildings regulations created a separate Principal Designer role for higher-risk buildings, focused on building regulation compliance and gateway approvals, sitting alongside a Principal Contractor with parallel duties. The two roles overlap in name but differ in scope, trigger, regulator and consequence. Any firm signing up as Principal Designer on a residential block of 18 metres or more needs to understand that it is taking on both. This guide sets out the dual exposure, the competence question, and how PI cover responds.
The CDM 2015 Principal Designer is concerned with health and safety. The role exists to ensure design risks are identified and managed before they reach the construction phase. It is a Health and Safety Executive enforcement matter at the regulatory level, with the principal civil exposure being to workers, occupiers and third parties under common law negligence, the Occupiers’ Liability Acts and the Defective Premises Act 1972.
The BSA Principal Designer is concerned with building regulation compliance. The role applies only to Higher-Risk Buildings — broadly residential structures of 18 metres or seven storeys with at least two residential units, plus care homes and hospitals of equivalent height — and exists to coordinate design across disciplines so that the as-designed building complies with the Building Regulations. The regulator is the Building Safety Regulator within the Health and Safety Executive, and the civil exposure feeds through to Defective Premises Act 1972 liability on a thirty-year retrospective and fifteen-year prospective tail under Building Safety Act 2022, section 135.
For an architect or lead consultant on a Higher-Risk Building scheme, taking on both roles is the default. The two duties are different but not contradictory: a single design coordination exercise can satisfy both, provided it is documented to both standards. The exposure is not double-counted in the sense of being the same claim twice — but it is dual in the sense of two separate sources of statutory duty, each with its own breach analysis, each capable of being the subject of a separate claim or regulatory action.
The competence question is now front-loaded. Under the BSA dutyholder regime, a firm appointed as Principal Designer must be able to demonstrate the competence to perform the role at the point of appointment. That is a contractual and regulatory obligation, and it is the basis on which insurers now underwrite the role. Practices that cannot evidence competence — through documented design review processes, named designers with relevant accreditation, and a clear scope of appointment — are seeing terms restricted or declined.
Professional indemnity cover responds to a claim alleging breach of professional duty, whether that duty arises in contract, tort or statute. The Principal Designer role under both regimes is professional in character, so a claim — whether civil from a developer, freeholder or leaseholder, or a regulatory cost-of-defence claim from a Health and Safety Executive investigation — will normally fall within the insuring clause of a standard PI wording, subject to definitions and exclusions.
The structural questions are:
For RICS-regulated firms the Minimum Approved Wording sets a floor. For ARB-regulated architects the standard is “adequate and appropriate” cover — qualitative rather than prescriptive, which puts the burden on the firm to evidence that its cover is fit for the role. The Supreme Court decision in URS Corporation Ltd v BDW Trading Ltd [2025] UKSC confirmed that a professional’s duty in tort can extend to a developer who voluntarily remediates — a relevant marker for any Principal Designer working with a developer client.
A six-partner architectural practice is appointed as architect, CDM Principal Designer and BSA Principal Designer on a 28-metre residential development. The scheme reaches gateway two; the Building Safety Regulator queries the compartmentation strategy and refuses the application pending revisions. The developer alleges the practice failed to coordinate the structural and fire engineering disciplines, causing six months of delay and £1.4m of carrying cost.
The practice notifies its PI insurer. The wording defines professional services to include dutyholder appointments and statutory roles. The fire safety exclusion is drafted to exclude “claims arising from the actual or alleged combustibility of external wall systems” — narrowly enough not to bite on a compartmentation coordination failure. Defence costs sit outside the £10m each-and-every limit. The practice’s broker engages early to confirm aggregation treatment in writing — single occurrence, single erosion of the limit — before substantive defence work begins. The matter settles at £900,000 with £350,000 defence costs, well within the programme.
Build a Principal Designer dossier and put it in front of underwriters early. The dossier should include named designers, accreditation evidence, recent project list with HRB status flagged, competence assessment process, and the firm’s standard appointment scope and fee structure for the role. Underwriters who see the dossier price the role differently from underwriters who only see the cover note.
On the wording, push for:
Test the run-off price as well as the in-force price. A Principal Designer appointment on a HRB scheme creates a fifteen-year prospective tail under Building Safety Act 2022, section 135. The run-off market signal tells you how the market views your exposure on that tail.
Apex’s view: The dual Principal Designer exposure is being underpriced by firms that have not yet had a BSR challenge land on a live scheme. We continue to advise that the wording extension covering statutory dutyholder roles should be express, not implied, and that the fire safety exclusion should be negotiated by reference to its actual scope — not its label. We also advise that any practice taking on the BSA Principal Designer role on a HRB scheme builds the competence dossier before the first appointment, not after the first claim. The Building Safety Regulator is now in its operational phase and is enforcing competence as the gateway, not as the audit afterthought.
Apex Insurance Brokers serves UK professional services firms and commercial businesses. Call 0117 325 0027, email hello@apexinsurancebrokers.co.uk, or request a quotation.
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