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Architects' insurance
Insurance for a mid-sized architecture practice is the package of covers a firm of roughly 10 to 50 staff needs, led by professional indemnity insurance. It matters because larger projects, collateral warranties and Building Safety Act duties increase both the size of potential claims and how long they can be brought.
Part of: Architects and surveyors insurance
In short
Under the ARB's 2025 Architects Code, Standard 4 expects architects to hold adequate and appropriate professional indemnity insurance. ARB guidance sets a £250,000 minimum on an each and every claim basis, with aggregate cover accepted for fire safety, cladding, asbestos and pollution. A mid-sized practice usually needs far more, set by its largest contracts and warranties. The Building Safety Act 2022 added dutyholder roles and extended Defective Premises Act limitation to 15 years, or 30 years retrospectively. Alongside PI, practices commonly buy office, cyber, compulsory employers' liability and management liability cover, and plan for at least six years' run-off.
A practice of roughly 10 to 50 people usually looks different from a small studio in ways that matter to insurers. Commissions are larger and run over several years. Clients and funders ask for collateral warranties and higher indemnity limits. The firm may be novated to a contractor on design and build projects, take on principal designer appointments, work on residential blocks, or operate from more than one office, with more staff and more client data on its systems. It is often a limited company or LLP, with directors or members who carry their own personal exposure.
Illustrative scenario. A 30-person practice wins a mixed-use scheme with flats above retail. The client's appointment asks for a higher PI limit than the practice holds, warranties to a funder and future tenants, and acceptance of the principal designer role under the Building Regulations. Each of these touches the insurance programme before the contract is signed.
Under the ARB's 2025 Architects Code of Conduct and Practice, Standard 4 (Professional practice) expects architects to ensure their liabilities are covered by adequate and appropriate professional indemnity insurance. ARB's PII guidance supports it and says, in summary:
For RIBA Chartered Practices, the RIBA's eligibility criteria require valid professional indemnity insurance or equivalent. Apex compares the bodies in ARB vs RIBA vs CIAT requirements.
For a mid-sized practice, the regulatory minimum is rarely the deciding figure. The limit is usually driven by the largest appointment, warranty and lender requirements, and the realistic cost of a serious claim. Apex's data on the PI limits UK firms ask for and why a practice may need higher limits cover this. Higher limits are often bought as layered programmes, so the excess layers need to follow the primary wording.
A collateral warranty gives a third party, such as a funder, purchaser or tenant, a direct contractual right against the architect. PI usually responds to liability under warranties, subject to the policy terms, but insurers commonly expect the warranty to be no more onerous than the appointment. Points to review:
More in collateral warranties and your PI programme.
The Building Regulations etc. (Amendment) (England) Regulations 2023 came into force on 1 October 2023 and inserted Part 2A, Dutyholders and competence, into the Building Regulations 2010. It sets duties for the client, principal designer, principal contractor, designers and contractors. A client must appoint a principal designer and principal contractor where there is, or is reasonably likely to be, more than one contractor. Individuals need the skills, knowledge, experience and behaviours for the work, and organisations need organisational capability. A firm appointed as principal designer must designate a competent individual to manage the role. See principal designer exposure for architects.
Section 135 of the Act, in force from 28 June 2022, inserted section 4B into the Limitation Act 1980. Claims under section 1 of the Defective Premises Act 1972 that accrued before that date now have 30 years; claims accruing afterwards have 15 years. The 15-year period also applies to the new section 2A, which imposes a duty on anyone who, in the course of business, takes on work to a building containing dwellings. See the section 135 limitation extension.
Illustrative example. A section 1 claim that accrued when a block of flats was completed in 2000 would previously have been out of time in 2006. Under the retrospective 30-year period it can be brought until 2030, subject to the court's power to dismiss a claim where needed to protect a defendant's Convention rights.
For insurance, the effect is a longer tail. Principal designer appointments and work on residential buildings usually need to be declared, fire safety cover may be aggregate-limited, and records need keeping for far longer than six years.
| Cover | What it usually does | Notes for a practice of this size |
|---|---|---|
| Office and business interruption | Contents, IT equipment and loss of income after damage | Check sums insured and the indemnity period. See office insurance for professional firms |
| Cyber | Incident response, data restoration, ransomware and privacy liability | PI wordings often exclude or limit cyber events. See cyber insurance for architects |
| Employers' liability | Injury or illness of staff caused by their work | Compulsory: at least £5 million from an authorised insurer. See EL for professional firms |
| Public liability | Injury or property damage to third parties at the office or on site visits | Separate from PI, which covers professional advice and design |
| D&O and management liability | Directors or members personally, employment practices claims and crime | More relevant as headcount and outside investment grow. See management liability insurance |
| Run-off | PI after the practice closes, merges or is sold | ARB guidance: at least six years (five in Scotland) at the final year's level. See run-off cover for architects |
ARB's Architects Code expects architects to have adequate and appropriate professional indemnity insurance. Its PII guidance sets a minimum of £250,000 on an each and every claim basis, with aggregate cover accepted for fire safety and cladding, asbestos and pollution, and at least six years of run-off after ceasing practice.
There is no single answer. The limit is usually set by the largest appointment and warranty requirements, the type of projects and the potential cost of a serious claim. Mid-sized practices commonly hold well above the ARB minimum, sometimes through a primary policy with excess layers.
Usually, subject to the policy terms. Insurers commonly expect a warranty to be no more onerous than the underlying appointment. Fitness for purpose obligations are often excluded, and warranties executed as deeds can extend liability to 12 years, so terms should be checked before signing.
ARB's PII guidance expects at least six years of run-off cover after a practice ceases, or five years in Scotland, held at the same level as the final year of practice. Longer periods may be sensible where deeds or Defective Premises Act claims could arise.
Section 135 of the Building Safety Act 2022 extended the limitation period for Defective Premises Act section 1 claims to 30 years for claims that accrued before 28 June 2022, and 15 years for claims accruing after that date. Other limitation periods, such as those in contract or negligence, still apply separately.
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