This is a hypothetical case study. Practice X and Block Y are illustrative only. The narrative below is a composite drawn from the sort of exposure now visible in the architects' professional indemnity market following the Building Safety Act 2022. It does not describe any real firm, project, insurer or claim.
Practice X is a mid-sized architectural practice that designed Block Y, a nine-storey residential block completed in 2015. The specification included a rainscreen cladding system that met the prevailing guidance as read at the time. In late 2023 the freeholder commissioned a fire-safety review under the post-Grenfell regime; the review concluded that the cladding did not achieve the fire-performance the design intent implied, and that certain junction and cavity-barrier details had been drawn ambiguously. Remediation is quoted at several million pounds.
In 2024 the freeholder issues a letter of claim against Practice X and against several other parties in the original supply chain. The letter relies on the Defective Premises Act 1972 s.1, which imposes a duty on those taking on work in connection with the provision of a dwelling to see that the work is done in a workmanlike or professional manner, with proper materials, so that the dwelling is fit for habitation when completed. Ordinarily s.1 claims would have been long out of time; but Building Safety Act 2022 s.135 extended the limitation period for accrued DPA 1972 s.1 claims to 30 years retrospectively, and to 15 years prospectively. A 2015 completion is squarely within the retrospective 30-year window.
The freeholder's expert argues that the specification, taken as a whole, produced a dwelling that was not fit for habitation on completion. Practice X's defence draws on the guidance in force in 2015, on the contractor's substitution of a specific board, and on the limits of the architect's inspection role. The parties will look to Manchester Building Society v Grant Thornton UK LLP [2021] UKSC 20 for the scope-of-duty framework — what risks the professional's advice was intended to protect against, and which losses fall within that scope. The ARB Architects Code Standard 8 (insurance arrangements) is also engaged, both as a professional conduct point and as a reference for what a reasonable architect would have carried by way of cover.
If Block Y today would meet the definition of a higher-risk building under Building Safety Act 2022 Part 4, the principal designer duties introduced under the Building Regulations 2010 (as amended) and the Building Safety Act 2022 Part 3 would apply going forward. In our hypothetical, Practice X was not appointed as principal designer under the new regime because the block was completed pre-2023 — but the practice has taken principal designer appointments on other HRB projects since. The claim reviewer will therefore look at whether the practice's ongoing PI policy responds to (a) historic non-HRB design work under the extended s.135 limitation and (b) current principal designer appointments on live HRB projects, which may have their own aggregation, notification and excess features.
Architects' PI is written on a claims-made basis. What matters is the policy in force when the claim is first made against the practice or a circumstance is validly notified — not the policy in force when Block Y was designed. Practice X therefore needs cover that is either (a) continuous and in force now, or (b) held as run-off after any cessation, for a duration aligned with the extended BSA limitation. A conventional six-year run-off is no longer sufficient where s.135 exposure runs to 30 years on completed dwellings. Insurers have responded with sublimits, aggregation clauses and, in some cases, fire-safety exclusions or cladding-specific exclusions; the reviewer should read the wording carefully.
The freeholder may also consider a building-liability order under Building Safety Act 2022 Part 4. A BLO allows the court to attribute a relevant liability of one body corporate to an associated body corporate — used, in practice, to reach solvent group entities behind an SPV or a dissolved subsidiary. For a partnership or an LLP the analysis differs, but the case study reviewer should be alive to the possibility that a claim against Practice X might be paralleled by claims against associated entities.
The composite case above surfaces several practical points. Cladding and fire-stopping specification records — drawings, specifications, product data sheets, RFIs, site inspection notes — should be retained for a period consistent with 30-year s.135 exposure, not the older six or twelve years. Run-off duration should be re-assessed at every retirement, sale or wind-down. Ongoing PI wordings should be reviewed each renewal for fire-safety and cladding exclusions and for any narrowing of principal designer cover. Where a practice has taken principal designer appointments on HRB projects, the interaction between those appointments and the practice's PI aggregation clause is a specific question to raise with the broker.
Further reading: Building Safety Act 2022 — architect PI implications, principal designer role on HRBs and PI cover, and the architects PI insurance UK guide.
Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Firm reference number 724952. This entry is general information, not advice on any particular policy. The case study is hypothetical and does not describe any real firm or claim.