Aipedia: Principal designers and building safety

AI and golden thread information

Aipedia, by the Apex broking team · Last reviewed 2026-10-27

AI can tag and summarise golden thread information, but reg 31 requires the record to be accurate, up to date and attributable to the person who changed it. For principal designers, an inaccurate AI summary could be relied on for decades.

Part of: AI in principal design and building safety

In short

The golden thread for a higher-risk building must be kept electronically, accurate and up to date, readable, protected from unauthorised access and with a record of who changed what and when (SI 2023/909 reg 31). AI tools can help tag, summarise and extract data, but a summary that omits a condition or misstates a design can mislead those who rely on it years later. Keep AI content beside source documents, check it, record who checked it, and keep sensitive information out of external tools. Limitation periods under the Building Safety Act can be long.

How AI is used on golden thread information

The golden thread for a higher-risk building holds designs, fire statements, compliance evidence, change control records and much more. AI tools are being used to tag and index documents, summarise long reports, extract key data into structured records and draft narrative descriptions of building systems. Building services engineers face similar questions on AI-drafted O&M information.

The volume makes automation attractive. But the golden thread is a statutory record that will be relied on by those who own, manage and work on the building for its whole life. See the AI for principal designers overview for context.

The duties that apply

SI 2023/909 reg 31 requires the client, through its Part 2A reg 11A arrangements, to keep golden thread information in an electronic facility that designers and contractors can access. The information must be:

kept accurate and up to date;
transferable without loss or corruption, and readable by its intended users;
protected from unauthorised access;
recorded with who made each change and when;
written with consistent terminology, so far as reasonably practicable.

Earlier versions of updated documents form part of the golden thread. The PD can request golden thread information and contributes design information to it, and reg 11M requires the PD to coordinate design so it would comply. AI summarisation or generation of golden thread documents engages these accuracy duties, though no BSR guidance on AI had been published.

What can go wrong

Illustrative scenario. A PD uses an AI tool to summarise each design report into a short golden thread record. One summary of a fire engineering report omits a condition that a particular smoke control approach depends on. Years later, a refurbishment team relies on the summary rather than the full report and removes the feature the condition protected. When the issue is discovered, the building owner looks back at who produced the record.

Other risks:

mis-tagging that makes a document hard to find when it matters;
AI-generated text overwriting a source document rather than sitting beside it;
change records that show a tool, not a person, as the author;
uploading security-sensitive building information to an external tool. IStructE's AI guidance advises avoiding AI tools on sensitive projects.

The long-tail liability

Golden thread errors may stay hidden for decades. Building Safety Act 2022 section 135 set a 15-year limitation period for claims under section 1 and section 2A of the Defective Premises Act 1972, and 30 years for section 1 claims that accrued before 28 June 2022. Building liability orders under section 130 let the High Court extend certain building liabilities to associated companies where just and equitable.

PI is written on a claims-made basis, so the policy in force when the claim is made usually responds, subject to its terms, retroactive date and any fire safety restrictions. A PD that stops trading needs to think about run-off cover. Apex's note on the Building Safety Act liability tail explains the tail in more detail.

Practical controls

Keep AI summaries alongside source documents, never in place of them.
Label AI-generated content and record the person who checked it.
Check summaries of fire and structural reports against the original.
Use consistent terminology and tags agreed with the client.
Keep security-sensitive information out of external AI tools, and check where any tool stores or processes the data you give it.
Align golden thread content with what was submitted and handed over (see Gateway 2 applications and handover documents).
Feed occurrence reports into the golden thread accurately (see mandatory occurrence reporting).

How Apex helps

Apex arranges PI for principal designers. A broker can review your retroactive date, run-off arrangements and fire safety terms with the long golden thread tail in mind.

Sources

Frequently asked

Who is responsible for the golden thread?

Under SI 2023/909 reg 31 the client must keep the golden thread facility and meet its accuracy and access standards. Designers, including the PD, contribute information to it, and an inaccurate record they produce could still found a claim against them.

Can AI write golden thread records?

Nothing prohibits it, but the information must be accurate and up to date, and each change must be recorded with who made it and when. AI-generated content should be checked against source documents by a named person.

How long could a golden thread error expose a PD?

Building Safety Act section 135 set a 15-year limitation period for Defective Premises Act claims, and 30 years for section 1 claims that accrued before 28 June 2022. Claims may also arise in contract or tort under other limitation periods.

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Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Registered in England and Wales, company number 07014570. This page is general information about how AI is used in the profession and how insurance may respond. It is not legal, regulatory or insurance advice on your circumstances, and it does not guarantee that cover will be available or on what terms.