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Short answer. Section 135 of the Building Safety Act 2022 extended the limitation period for claims under s.1 of the Defective Premises Act 1972 to fifteen years for future claims and thirty years retrospectively. That is far longer than the six years of run-off ARB guidance expects architects to hold, which is why practices with historic residential work need to think about the gap.
The Limitation Act 1980 sets the ordinary time limits within which a professional negligence claim can be brought. Section 2 gives a claimant six years from the date the cause of action accrues to bring a claim in tort; section 14A extends that period to three years from the date on which the claimant first had knowledge of the relevant facts; and section 14B imposes a 15-year long-stop from the negligent act or omission itself. For most professional indemnity claims against architects and other design professionals, this framework has for decades defined the outer edge of the run-off risk that a practice needed to insure against.
The Building Safety Act 2022, and in particular section 135, has rewritten that boundary for one important category of work.
Section 1 of the Defective Premises Act 1972 imposes a duty on those taking on work in connection with the provision of a dwelling to ensure the work is done in a workmanlike or professional manner, with proper materials, so that the dwelling is fit for habitation when completed. Before June 2022, a claim under section 1 of the DPA had to be brought within six years of the date the dwelling was completed. In practice this meant that any DPA exposure on a residential design was effectively closed off six years after practical completion.
The pre-2022 and post-2022 positions described above sit within a wider set of statutory limits, collected below.
| Route of claim | Time limit | Runs from | Source |
|---|---|---|---|
| Breach of simple contract | Six years | The date the cause of action accrued | Limitation Act 1980, s.5 |
| Negligence (tort) | Six years | The date the cause of action accrued | Limitation Act 1980, s.2 |
| Latent damage — negligence | Three years | The starting date defined in s.14A(5), where later than the six-year period | Limitation Act 1980, s.14A |
| Long-stop for negligence (not personal injury) | Fifteen years | The last act or omission alleged to constitute negligence | Limitation Act 1980, s.14B |
| Action on a specialty (a contract executed as a deed) | Twelve years | The date the cause of action accrued | Limitation Act 1980, s.8 |
| Defective Premises Act 1972 s.1 — prospective claims | Fifteen years | The date the right of action accrued | Building Safety Act 2022, s.135 |
| Defective Premises Act 1972 s.1 — retrospective claims | Thirty years | The date the right of action accrued | Building Safety Act 2022, s.135 |
Sources: Limitation Act 1980 ss.2, 5, 8, 14A, 14B (legislation.gov.uk); Building Safety Act 2022 s.135 (legislation.gov.uk). Legal time limits, not policy terms — a claims-made PI policy only responds if cover is in force when the claim is made.
Section 135 of the Building Safety Act 2022 amended the Limitation Act 1980 in respect of DPA section 1 claims. Two distinct regimes now apply:
Building Safety Act 2022 s.135 extended the limitation period for Defective Premises Act 1972 s.1 claims to 15 years prospectively and 30 years retrospectively, far beyond the six-year run-off most professionals buy.
The DPA applies to dwellings. Purely commercial buildings do not fall within section 1, although mixed-use schemes with a residential element will. The extended limitation regime therefore bites hardest on architects, engineers, and design-and-build contractors whose portfolios contain residential blocks, mixed-use developments, and higher-risk buildings.
Because the retrospective provision took effect on 28 June 2022, work completed from 28 June 1992 onwards potentially falls within its scope. A design that was completed in 2010, and that under the pre-BSA regime would have been out of DPA limitation by 2016, is now potentially claimable until 2040. That is a 24-year expansion of the tail on a single project.
In URS Corporation Ltd v BDW Trading Ltd [2023] EWCA Civ 772 the Court of Appeal considered how the transitional provisions of the Building Safety Act operate. The court confirmed that the retrospective extension in section 135(1) applies to accrued causes of action that would otherwise have been time-barred, and that this reaches into positions the parties may have previously treated as settled. The judgment reinforced that the extended window is not a narrow drafting curiosity but a substantive reopening of long-tail exposure.
Worked example: an architectural practice designed a residential block completed in 2005. The partners retired in 2020 and, on the advice they took at the time, purchased a six-year run-off policy expiring in 2026. Under section 135(1) of the Building Safety Act 2022, a DPA section 1 claim in respect of the 2005 design is now time-barred only in 2035 — 30 years from completion. The six-year run-off ends in 2026, nine years before the limitation window closes. The practice is exposed for nearly a decade on a project it can no longer service, without the professional indemnity policy in place to respond.
The six-year run-off that was, for many years, the industry default is now materially inadequate for practices whose historic work includes residential dwellings, and particularly higher-risk buildings within the meaning of the Building Safety Act. Design professionals looking to close a practice, retire, or restructure need to consider extended run-off periods, alternative funding vehicles, or the position their successor practice can offer. Practices still trading need to keep the DPA exposure in mind when reviewing limits of indemnity at renewal, and when reading the wording of insuring clauses and exclusions relating to fire safety, cladding, and higher-risk buildings.
Apex Insurance Brokers arranges professional indemnity cover for architects, engineers, and design-and-build contractors, and can review the interaction between a firm's historic residential portfolio and its current or run-off PI arrangements. Related guides on this site include the architects' PI guide, the engineers' PI guide, and the design-and-build contractors' PI guide. Related wiki entries include Building Safety Act 2022: architect PI implications and Limitation Act 1980 section 14A and professional negligence.
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.
A thirty-year lookback outlasts any published run-off period, which is what makes the requirements below a floor rather than an answer.
| Regulator / body | Run-off period required | Level of cover | Notable condition |
|---|---|---|---|
| SRA (solicitors) | An additional six years from the end of the policy period | Complying with the Minimum Terms, subject to the run-off limits in the MTC | Triggered by cessation during or on expiry of the policy period |
| ICAEW (chartered accountants) | At least two years, then all reasonable steps to put compliant cover in place for a further four years | As a minimum, the minimum limits of indemnity in regs 3.2–3.5 | Run-off is a mandatory requirement of the regulations |
| RICS (chartered surveyors) | Six years expected for non-consumer claims; £1m in all for six years for consumer claims | Fully retroactive run-off | Insurers may not charge an additional premium for the consumer run-off element where premium has been paid |
| ARB (architects) | A minimum of six years, or five years in Scotland | The same level as the last year before cessation | Deeds carry a twelve-year liability period, so ARB warns that six years may not be enough |
Sources: SRA Minimum Terms and Conditions clause 5 (sra.org.uk); ICAEW PII Regulations effective 1 September 2024, run-off and cessation of practice (icaew.com); RICS PII requirements 2 July 2025, run-off cover (rics.org); ARB PII Guidance paras 6.2–6.3 (arb.org.uk).
Section 135 of the Building Safety Act 2022 provides a fifteen-year limitation period for claims accruing after commencement and a thirty-year period for claims that had already accrued before it came into force.
ARB guidance sets six years as the minimum, five in Scotland, but also warns about liabilities extending beyond the normal statutory time limits, including contracts made under seal, where the period is twelve years, and claims under the Defective Premises Act.
