RIBA vs ARB for architects: professional body, statutory regulator, and how PII sits under each

Reviewed by Apex Insurance Brokers · Last reviewed 2026-07-06

Short answer. ARB is the statutory regulator of the title architect, and its PII guidance sets the insurance floor: £250,000 each and every claim and at least six years of run-off, five in Scotland. RIBA membership is voluntary; the RIBA Code of Practice requires Chartered Practices to address liability and insurance in their terms of appointment, and RIBA publishes guidance rather than its own minimum.

Two acronyms dominate the discussion when architects talk about their regulatory and professional environment: ARB, the Architects Registration Board, and RIBA, the Royal Institute of British Architects. They are frequently confused. They do different things, they have different powers, and they impose different (though largely aligned) expectations on PII. This entry sets out what each is, what each requires, and what an architect dual-affiliated with both needs to check.

What the ARB is

The ARB is the statutory regulator of the architectural profession in the UK. Established by the Architects Act 1997, it holds the Register of Architects and has the statutory duty to protect the public by ensuring only competent, ethical architects are permitted to use the title "architect" in the UK. ARB registration is mandatory for anyone using the title. The ARB has statutory disciplinary powers: it can investigate complaints, sanction registrants, and remove architects from the Register. The Code of Conduct and Practice, including Standard 8 on PII, is binding on all registrants.

The ARB does not train architects, does not lobby for the profession, and does not provide member services. It is a regulator, not a membership body. Its funding comes from registrants' annual retention fees; its governance sits with a board appointed under the Architects Act.

What the RIBA is

The RIBA is a professional body — a voluntary membership organisation for architects. Founded in 1834 and holding a Royal Charter, it provides training, thought leadership, professional development, awards, publications, and the RIBA Plan of Work that structures architectural project delivery. RIBA membership is a mark of professional standing rather than a licence to practise. An architect can be ARB-registered without being a RIBA member; a RIBA member without ARB registration cannot use the title "architect" in the UK.

The RIBA has its own Code of Professional Conduct binding on its members. The Code broadly mirrors the ARB Code but with additional expectations around ethical conduct, professional development, and — relevant here — PII.

PII under the ARB Code

Standard 8 of the ARB Code of Conduct and Practice requires "adequate and appropriate" PII cover. The framework is discussed in detail in the entry on the ARB Code Standard 8 framework. In summary, adequacy is judged by the nature and value of the work, claims history, and specific role exposures. No fixed minimum figure is prescribed; the ARB operates an adequacy standard supported by guidance.

ARB guidance expects a minimum limit of indemnity of £250,000 on an each and every claim basis, and a minimum of six years of run-off cover — five years in Scotland — held at the same level as the last year before the practice ceased.

PII under the RIBA Code

The RIBA Code of Professional Conduct requires members in practice to hold PII adequate to their business. The RIBA's guidance is more prescriptive than the ARB's in some respects — it specifies minimum wording expectations (for example, on defence costs and on aggregation) and provides indicative minimum limit ranges for different practice sizes. RIBA-Chartered Practice status carries additional PII requirements as part of the practice-accreditation framework.

Where an architect is a RIBA member and the practice is a RIBA-Chartered Practice, the effective PII requirements are set by RIBA rather than by ARB, because RIBA's expectations are typically higher than the ARB's adequacy standard. The ARB standard remains binding on the individual; the RIBA standard operates in addition. Apex has been placing professional indemnity for 17 years, and our page on how we approach architects PI placements sets out the approach.

Where the two align

The two regimes align on the core question: PII must be in place, and it must be adequate to the work. Both regimes recognise the same factors — nature of work, value of projects, claims history, specific role exposures — as relevant to adequacy. Both regimes require cover to continue after cessation for a residual tail, though neither prescribes a fixed period. In practice, most architectural PII placements satisfy both regimes with a single wording; the broker's job is to confirm that at every renewal.

Where the two diverge

Three points of divergence recur. First, wording specificity: the RIBA guidance is more prescriptive than the ARB's. A wording that satisfies the ARB adequacy standard may fall short of RIBA-Chartered Practice expectations on defence costs or aggregation. Second, minimum figures: the RIBA indicates preferred minimums by practice size; the ARB does not. Third, evidence: the RIBA has more established documentation expectations at practice-accreditation level than the ARB has for individual registrant compliance.

The RIBA-Chartered Practice layer

A practice that holds RIBA-Chartered Practice status carries specific PII expectations linked to accreditation. These include limit thresholds tied to the practice size, wording requirements on defence costs and reinstatements, and continuing evidence obligations at annual re-accreditation. Practices considering RIBA-Chartered Practice status should engage a broker to confirm the placed policy meets the accreditation requirements — a policy compliant for a non-chartered practice may not be for the chartered one.

Devolved and international dimensions

The ARB regulates architects using the title in the UK. Devolved administrations do not have separate regulators — the ARB's writ runs to England, Wales, Scotland and Northern Ireland. Architects working in Ireland fall under the Royal Institute of the Architects of Ireland (RIAI); those in the Republic of Ireland must be RIAI-registered. Architects working internationally from a UK base face the additional question of jurisdictional PII exposure, and any policy should be checked at each engagement for cover on work outside the UK.

Practical points for individual architects

Three practical points recur. First, confirm at every renewal that the policy meets both ARB adequacy and RIBA guidance if you hold both affiliations. Second, if the practice is RIBA-Chartered, confirm the policy meets the Chartered Practice accreditation requirements — the broker should be able to produce a written note. Third, keep both bodies' expectations in mind at proposal-form stage: complete the proposal against the higher-water-mark expectations, not the lower.

Architects: where the PI requirement actually comes from

The professional body and the statutory regulator sit differently in relation to PI, and the table below shows exactly how.

Body	Status	What it requires on PI	Minimum limit	Run-off
ARB (Architects Registration Board)	Statutory regulator of the title “architect”	Standard 8 of the Architects Code expects adequate and appropriate PI cover for you, your practice and your employees, maintained in accordance with ARB guidance	£250,000, each and every claim, save that fire safety, cladding, asbestos and pollution may be written on an aggregate basis	A minimum of six years, five in Scotland, at the same level as the last year before cessation
RIBA	Membership body; publishes guidance, not registration	The RIBA Code of Practice for Chartered Practices requires terms of appointment to cover liability and insurance; RIBA publishes a Guide to Professional Indemnity Insurance	Not published as a separate RIBA figure in the sources cited here	Not published as a separate RIBA figure in the sources cited here
CIAT	Membership body for chartered architectural technologists	Not published in the sources cited here	Not published in the sources cited here	Not published in the sources cited here

Sources: ARB PII Guidance paras 2.2, 3.2, 4.2, 6.2 (arb.org.uk); RIBA Guide to Professional Indemnity Insurance 2024, quoting ARB Code Standard 8, and RIBA Code of Practice cl. 9.1–9.2 (riba.org). Cells marked “Not published” were not stated in the sources cited; they are not an assertion that no requirement exists.

Worked example

Illustrative only. A four-partner practice, three ARB-registered, all four RIBA members, RIBA-Chartered Practice status. Fee income £1.4m, mixed commercial and residential. Broker action: PII policy placed to meet RIBA-Chartered Practice accreditation requirements (which exceed ARB adequacy on defence costs treatment and aggregation), £3m primary layer with contract administration endorsement, six-year run-off costed as a planning number. Documentation memo issued at binding confirming compliance with both regimes.