Higher PI Limits — Architects

Why your architects practice may need higher PI limits — UK 2026

The £1m or £2m aggregate that served a mid-size UK architects’ practice through the 2010s does not, in every case, still serve the same practice in 2026. This page sets out the substantive reasons the case for higher aggregate limits has strengthened, without recommending a specific product or premium.

Reviewed by Matthew Bartlett, Director, Apex Insurance Brokers Limited (FCA FRN 724952) · Published 16 July 2026

Where the market was, and where it is now

Through much of the 2010s a common shape of PI cover for a UK architects’ practice was £1m or £2m in the aggregate, on a claims-made basis, with any excess-of-loss layer bolted on for particular projects rather than as a standing programme. That was defensible against the exposure landscape of the time. Section 1 of the Defective Premises Act 1972 gave a claimant six years from completion; the Latent Damage Act 1986 extended that in negligence to (at most) 15 years from the act or omission complained of. Cladding was not a widely-underwritten concern. The ARB’s Standard 8 on adequate insurance was applied in a broadly stable way.

Since June 2022 the picture has moved. Section 135 of the Building Safety Act 2022 amended section 1 of the Defective Premises Act 1972 to extend the actionable window for claims relating to dwellings to 30 years retrospectively and 15 years prospectively. Grenfell-era cladding litigation reshaped underwriting appetite. Contractual demands from developers and public bodies pushed required limits upwards. And the ARB, in its 2024 Architects Code review, restated Standard 8’s requirement that architects hold adequate cover, without prescribing a specific limit but making clear the assessment is dynamic.

The BSA 2022 section 135 argument in plain terms

Section 135 does two things: it extends the limitation period, and it applies that extension retrospectively. What that means practically is that work an architect signed off in 1996, 2004 or 2012 — work which under the old regime had passed into an unrecoverable past — can, if it involves a dwelling, sit back inside the actionable window.

For a mid-size residential-adjacent practice, the exposure that follows is not linear with current turnover; it is a function of what the practice designed over 30 years. A £2m aggregate reads very differently against a back-catalogue of three or four hundred dwellings than against a portfolio that is entirely commercial.

Substantive point. Section 135 is not a theoretical risk. Multiple cases have already been pleaded relying on the extended DPA limitation period; commentators have referred to Fairview Estates v Waite [2024] as an early marker of how the courts will approach s.135 arguments. Whether the courts continue to construe the extension broadly or narrowly, the point for insurance purposes is that the past is now in scope in a way it was not.

ARB Standard 8 — adequacy as an evolving test

The Architects Registration Board’s Standard 8 of the Architects Code requires that “you have adequate and appropriate insurance cover for you, your practice and your employees”. The Standard does not fix a monetary minimum. The ARB’s guidance makes clear that adequacy is assessed against the nature and scale of the practice, the value of projects undertaken and the potential exposure.

Two things follow. First, a limit that was adequate five years ago is not automatically adequate today. Second, when the ARB revisits the Standard 8 test in light of the Building Safety Act, an architect defending their limit will need to show they thought about the question, not merely renewed at last year’s level.

Client-contract demands and appointment norms

The other pressure on limits is client-side. Standard-form architect appointments — the RIBA Standard Professional Services Contract 2020 and its successor forms, and the ACA/CIC forms — all contemplate the client specifying the required PI limit. In practice, the specified figure has moved:

An architect who tenders for that work with a £2m aggregate has either to increase the programme (probably via an excess layer for that project or across the book), decline the appointment, or negotiate the limit down — increasingly a losing argument on projects with a fire-safety-related design element.

Cladding, facades and residential concentration

The BSA and Fire Safety Act 2021 landscape has made cladding and facade design a permanent feature of PI underwriting. Insurers ask about it at renewal in a way they did not a decade ago. From an architect’s perspective, three sub-questions matter:

Manchester Building Society v Grant Thornton and the SAAMCO scope-of-duty question

Damages recoverable from a professional adviser are shaped by the scope-of-duty analysis first articulated in South Australia Asset Management Corporation v York Montague [1997] AC 191 (SAAMCO) and refined in Manchester Building Society v Grant Thornton UK LLP [2021] UKSC 20. The Supreme Court’s counterfactual test asks whether the loss claimed is within the scope of the professional’s duty.

For architects, this matters because it defines the upper bound of what a claim can recover. It does not, on its own, cap damages at any given number; it disciplines the argument. Practices with high-value output need to hold a limit that responds to the range of losses reasonably within the scope of their duty on the projects they take on.

What higher limits actually cost, proportionally

Excess-of-loss capacity is, in general, cheaper per pound of limit than primary. In a well-underwritten programme, doubling the aggregate by adding an excess layer rarely doubles the total premium; the marginal cost of higher aggregate is a fraction of the primary rate because the probability of a claim reaching that layer is lower.

This is not a promise about any particular practice. Excess capacity for a firm with a cladding-heavy back-catalogue and a modest primary is priced very differently from excess capacity for a commercial-focused practice with a clean claims history. The point is that higher limits are not linearly more expensive, and firms that assume they are may be under-buying by default rather than by considered choice.

The decision framework

A structured way to review whether a practice’s current aggregate limit still fits is to work through five questions:

  1. What is the practice’s residential design exposure over the last 30 years?
  2. What is the largest single-project loss the practice could conceivably face on current instructions?
  3. What limit is the practice being asked for in tenders and appointments over the coming 12 months?
  4. How does the current aggregate compare to peers of similar size and profile?
  5. Where would an increase in aggregate leave the primary/excess split, and what wording differences would that create?

None of these questions has an answer that is uniform across UK architects. What they share is that answering them explicitly is the substantive improvement over renewing at last year’s number by default.

Frequently asked questions

Does section 135 of the BSA 2022 mean my old projects are back in scope for PI claims?

In respect of work relating to dwellings, yes — the actionable window under section 1 of the Defective Premises Act 1972 was extended by section 135 BSA 2022 to 30 years retrospectively for causes of action accruing before 28 June 2022. The extension applies to the statutory cause of action under the DPA. Other causes of action (negligence, breach of contract) remain subject to their own limitation rules under the Limitation Act 1980.

Is there a ‘correct’ PI limit for an architects practice?

There is no prescribed monetary minimum in the ARB’s Architects Code. Adequacy is judged on the nature and scale of the practice and its exposure. Because that exposure moves with client mix, project scale and legislative change, the adequacy question is one to revisit on each renewal rather than a fixed figure.

Do I need higher limits if I only do domestic extensions?

The answer depends on the totality of the practice’s exposure over the retroactive period, not just its current work. A practice whose current book is small domestic work but which historically designed larger residential schemes may still have material section-135 exposure. The retroactive-date position on the current policy is the linked question to look at.

What is the aggregate limit and why does it matter?

The aggregate limit is the total the insurer will pay for all claims arising during a single policy year, before defence costs where the policy is written on a costs-inclusive basis. It matters because two or more claims in the same year draw from the same pot. Any-one-claim (each-and-every) limits, by contrast, apply per claim, which offers wider protection but is a more expensive structure.

How do public-sector frameworks specify PI limits?

Public-sector procurement frameworks typically prescribe a PI limit as a condition of the framework agreement. Frameworks operated by housing associations, local authorities and universities frequently specify £5m or £10m aggregate for architectural services. The specific figure is set out in the framework’s standard schedule and does not usually vary by call-off.

Can I buy a higher limit just for a specific project?

Yes — single-project PI (SPPI) is available and is sometimes the appropriate structure for a large one-off appointment. It has its own trade-offs: the SPPI limit is dedicated to that project and does not respond to other claims, and it needs to align with the practice’s standing programme for the same period. Whether SPPI or a higher standing aggregate is the better answer depends on the profile of the appointment.

Does higher PI cost proportionally more?

Not in general. Excess layers price cheaper per pound of limit than primary layers because the probability of a claim reaching them is lower. The precise cost of moving from, say, £2m to £5m aggregate depends on claims history, project mix and the primary wording — but it is not typically a doubled premium for a doubled limit.

Do I need to increase run-off cover as well as current-year cover?

Run-off cover indemnifies claims made after the practice has closed but arising from work done before closure. Because section 135 BSA 2022 extends the actionable window retrospectively, the argument for reviewing run-off adequacy has the same underlying driver as the argument for reviewing current-year adequacy. Where a practice is heading towards closure or a succession event, this is a distinct conversation to have alongside the standard renewal.

Related reading

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