This page covers the professional indemnity implications for the people who take on the Principal Designer role — either under the Construction (Design and Management) Regulations 2015 (SI 2015/51), or under the Building Regulations Principal Designer regime brought into effect on 1 October 2023 under the Building Safety Act 2022 framework. Both roles carry design co-ordination duties, both attract underwriter scrutiny, and both interact with the extended limitation periods that section 135 of the Building Safety Act 2022 wrote into the Limitation Act 1980. It is written for architects, engineers, surveyors, fire safety consultants and building control professionals who hold, or expect to hold, one or both roles.
The label "Principal Designer" now refers to two distinct legal roles, each created by its own statutory instrument. They can be held by the same firm on the same project, but they are not the same duty and insurers ask about them separately.
The Construction (Design and Management) Regulations 2015 (SI 2015/51) require the client on every construction project involving more than one contractor to appoint a Principal Designer under regulation 5. The duty is health and safety focused. Regulation 11 sets the obligations: plan, manage, monitor and co-ordinate health and safety in the pre-construction phase, and identify, eliminate or control foreseeable risks. The role is enforced by the Health and Safety Executive, and breach can carry criminal as well as civil consequences.
The Building Regulations Principal Designer is a separate statutory role, introduced by the Building Regulations etc. (Amendment) (England) Regulations 2023 (SI 2023/911) and in force from 1 October 2023. It sits inside the Building Regulations 2010 as amended, and it is a dutyholder role focused on compliance with the Building Regulations — structural, fire, thermal, ventilation and accessibility compliance in the design as built, not health and safety on site.
On a Higher-Risk Building the appointment is compulsory and must be a competent individual or organisation tested against the criteria in the Regulations. On non-HRB projects where the Building Regulations apply and more than one contractor is involved, a Building Regulations Principal Designer must still be appointed. That means most non-domestic and much domestic building work now falls inside the regime.
The same firm often holds both roles on the same project, which means answering both regulatory regimes and both sets of underwriter questions. The scopes overlap but do not coincide, and PI wording should be checked so that both are covered without a gap between them.
Section 135 of the Building Safety Act 2022 amended the Limitation Act 1980 by inserting a new section 4B. The provision applies to claims under section 1 or section 2A of the Defective Premises Act 1972 and to claims under section 38 of the Building Act 1984. For Principal Designers the section 1 DPA claim matters most — it is the direct route through which a dwelling owner sues the professionals who took a hand in providing an unfit dwelling.
The new limitation periods are:
The reach of that retrospective window is the reason underwriters have re-priced the market for anyone who did residential design work in the 1990s and 2000s. A dwelling completed in 1995 can now support a DPA 1972 section 1 claim brought nearly three decades after the last drawing left the office, and the firm's retroactive-date cover remains on the hook.
Section 135 is not confined to Higher-Risk Buildings. Any work "in connection with the provision of a dwelling" is within scope, so a Principal Designer who advises on the residential element of any mixed-use or purely residential scheme is exposed, as is a designer working on conversion of a non-residential building into flats.
The HRB definition matters because the Building Regulations Principal Designer regime, and the wider Building Safety Regulator regime, treat HRBs differently. Under the Higher-Risk Buildings (Descriptions and Supplementary Provisions) Regulations 2023 (SI 2023/275), a Higher-Risk Building is one that is at least 18 metres in height or has at least seven storeys, and contains at least two residential units. The height-or-storeys threshold is either/or; the residential unit threshold is separate and must also be met.
The 11-metre threshold sometimes cited is a different regime — Part 5 of the Building Safety Act (leaseholder protection) and the Fire Safety (England) Regulations 2022 (in-occupation duties). It is not the trigger for HRB design and construction. Principal Designers working on residential buildings between 11 and 18 metres should not assume they are outside the tighter design regime: the Building Regulations Principal Designer role still applies; only the additional Gateway process for HRBs is disapplied.
The Building Safety Regulator, part of the Health and Safety Executive, oversees Higher-Risk Building design and construction through three regulatory Gateways.
Each Gateway is a moment at which the Principal Designer's work is inspected. PI wording should be reviewed so that regulatory investigation defence costs, and cover for civil claims arising from Gateway refusals or completion certificate refusals, are addressed. A blanket "any liability arising from the Building Safety Act 2022" exclusion is now sometimes seen and should be resisted in favour of a narrower carve-out.
The underwriter conversation has changed materially since 2023. What used to be a set of general design questions is now a specific inquiry into HRB involvement, cladding history, external wall system design, fire safety consulting exposure, and Building Safety Regulator interaction. The following issues come up on almost every renewal.
Because section 135 revives historic claims for up to 30 years, the retroactive date on a professional indemnity policy has moved from a housekeeping detail to a material contract term. If a policy is placed on a claims-made basis with a retroactive date of, say, 2005, all pre-2005 work is uncovered — including work that could now attract a fresh DPA 1972 section 1 claim under the extended limitation. When switching insurers, insisting on preservation of the earliest possible retroactive date is essential. See our note on run-off insurance for the position after ceasing practice.
Two-million-pound minimum limits, still the default for many small architectural and engineering practices, are now often below what a defensible sizing exercise would produce. On residential work with HRB exposure, £5 million to £10 million per claim is now typical. The ARB and Engineering Council do not prescribe a figure — the standard is adequacy — judged against project pipeline, historic work and the aggregation of dwellings across schemes. Aggregation matters: a defective design co-ordinated across multiple units in a single HRB may aggregate under the claims clause, so a wording that aggregates on the "originating cause" treats a design defect as one claim, exhausting one limit for the whole block. Our note on aggregation clauses covers the point.
Some insurers now impose a sub-limit — sometimes as low as 25 per cent of the main limit — for HRB work or Building Regulations Principal Designer duties. Others exclude cladding-related work, or apply bespoke exclusions for the external wall system. Current wording should be read in full, not by reference to the schedule. Where a single firm holds both the CDM and Building Regulations roles, the professional services definition should be checked, especially on wordings drafted before 2023: some older wordings reference CDM 2015 only, leaving the Building Regulations role potentially uninsured.
Architects are the most common holders of the Principal Designer role. ARB Standard 8 requires them to hold and maintain adequate and appropriate professional indemnity insurance; the ARB does not set a numerical figure, but the adequacy test now takes into account section 135 exposure. Our guide to ARB Standard 8 covers the framework. Non-RIBA architects who take on Principal Designer work are equally within scope — see PI insurance for non-RIBA architects.
Structural engineers often lead Building Regulations design co-ordination on HRBs, particularly where structural design intersects with fire compartmentation and cladding fixing. The Engineering Council's UK-SPEC framework and the ICE and IStructE codes apply. The engineers PI guide sets out the market context.
Building services engineers co-ordinate the mechanical, electrical and public health design; on HRBs the interaction with fire safety strategy, smoke control and structural design is critical and specialised. Fire safety consultants now play a formal role in the Gateway process, and the specialist fire engineering PI market is narrow with tighter cover terms than general engineering.
Registered Building Control Approvers — the private building control profession introduced under the Building Safety Act 2022 — operate under their own regulatory regime supervised by the Building Safety Regulator. Their PI needs are distinct: statutory function work carries different exposure than design consultancy.
Building surveyors on due diligence are a frequently overlooked category. Advice given during acquisition of residential portfolios now sits inside the extended limitation window. See the surveyors PI guide for the wider position.
Presentation to insurers should now anticipate, and answer clearly, the following specific inquiries:
Under the Insurance Act 2015 this is a duty of fair presentation. Material facts must be disclosed clearly and accessibly to a prudent underwriter, and a submission that answers the letter of the question but not the substance can be reopened on renewal or claim.
Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority (firm reference number 724952). The practice is director-led — Matt Bartlett holds SMF3, SMF16 and SMF17 approvals — and works with insurers whose appetite for HRB and Principal Designer exposure has been tested. Submissions are prepared to respond specifically to the section 135 questions raised above.
Firms holding either Principal Designer role are welcome to send a current wording for review. Sub-limits, exclusions and retroactive-date issues will be identified, and cover placed with a named underwriter rather than a portal.
A statutory dutyholder role introduced by the Building Regulations etc. (Amendment) (England) Regulations 2023, in force from 1 October 2023, made under the Building Safety Act 2022 framework. The Principal Designer is responsible for planning, managing and co-ordinating the design work of the project team so that the design complies with all applicable Building Regulations. The role must be filled on every Higher-Risk Building project and on non-HRB projects where the Building Regulations apply and more than one contractor is involved.
Section 135 amended the Limitation Act 1980 to allow DPA 1972 section 1 claims to be brought up to 30 years after completion for work completed before 28 June 2022, and up to 15 years after completion for work completed on or after that date. That reopens historic residential design work for civil claims. For PI insurance it means retroactive dates matter more than ever, adequate limits are typically higher than they used to be, and insurers ask specific questions about historic HRB and residential design work.
No. The CDM role is a health and safety role under SI 2015/51. The Building Regulations role is a design compliance role introduced from 1 October 2023 under SI 2023/911. Different statutory bases, different regulators, different insurance implications. A single firm often holds both, but appointments and underwriter questions are separate.
Cover for the CDM role is generally within a standard architect's or engineer's PI wording. The Building Regulations role, being newer, is not always expressly named. On older wordings the professional services definition should be reviewed, and some insurers now impose sub-limits or exclusions for HRB Principal Designer work — those should be identified before renewal, not at claim.
The ARB requires adequate and appropriate cover under Standard 8; the Engineering Council frameworks apply the same test. For a small practice with no HRB exposure, £2 million may still be defensible. For residential and HRB work, £5 million to £10 million is now more typical, and larger schemes call for more. Sizing should be documented against project pipeline, historic work and aggregation risk, and reviewed at each renewal.
Yes, in most cases. PI policies are typically claims-made — cover responds only if the policy is in force when the claim is notified. Because section 135 allows claims many years after completion, run-off is essential when a firm ceases practice. The ARB requires six years for architects; other professions have their own periods, and longer run-off is worth considering for residential work. See our run-off guide.
Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Firm reference number 724952. This page is a general guide and does not constitute regulated advice on any specific transaction. Cover terms, limits and adequacy should be considered against the individual circumstances of the firm and its work.