Construction site records are no longer an administrative afterthought. Under the Building Safety Act, they are legal evidence.
On Higher-Risk Building projects, site records now form part of the statutory Golden Thread and are used by the Building Safety Regulator to assess whether a building can legally proceed through Gateway 2, reach completion at Gateway 3 and be safely occupied.
In London, where complex phasing, constrained logistics and multi-trade sequencing dominate delivery, record keeping has become one of the highest-risk compliance exposures on site.
If the records are missing, incomplete or unreliable, the project can be delayed, rejected or subject to enforcement action, regardless of whether the physical works are technically sound.
What counts as a construction site record under the BSA
Under the Building Safety Act, a construction site record is any information required to demonstrate that the building has been designed, constructed and commissioned in compliance with building regulations and the approved Gateway submissions.
This includes design information, construction records, inspection evidence, test results, change control documentation, competence records and handover information.
On BSR-regulated projects, records are no longer kept for convenience, they exist to prove regulatory compliance.
The Regulator treats these records as safety-critical data.
How long site records must be kept
There is no single retention period written into the Building Safety Act itself. Instead, record retention is defined through a combination of building safety law, building regulations, health and safety legislation, product liability law and the Golden Thread requirements.
In practice, this creates three overlapping time horizons.
1. Construction phase records
During construction, all site records must be retained in full for the entire duration of the project. This includes the full Gateway 2 to Gateway 3 period.
Nothing can be discarded while the building remains under regulatory control.
2. Gateway 3 and handover records
At completion, the Principal Contractor and Principal Designer must submit a complete, verified as-built information pack to the Accountable Person.
This becomes part of the statutory Golden Thread.
Once accepted by the BSR at Gateway 3, these records must be retained for the lifetime of the building.
3. Post-completion safety records
Once the building is occupied, the Accountable Person must maintain, update and preserve the Golden Thread for as long as the building remains in use.
There is no expiry date, if the building exists, the records must exist.
What lifetime of the building means in practice
The Golden Thread is a permanent legal obligation.
It must remain accurate, accessible, up to date and secure for the full operational life of the building, including refurbishments, material changes, remedial works and safety upgrades.
For most London residential towers, mixed-use developments and complex refurbishments, this means records must be retained for 60 to 100 years or more.
What happens if records are missing or incomplete
The Building Safety Regulator treats missing records as a safety risk.
On live projects, missing records can result in Gateway delays, enforcement notices, construction stoppages or refusal of completion certificates.
On occupied buildings, missing Golden Thread data can trigger compliance investigations, improvement notices and criminal liability for dutyholders.
In the event of a serious incident, missing records may expose contractors, designers and dutyholders to prosecution under the Building Safety Act, the Health and Safety at Work Act and corporate manslaughter legislation.
Records are no longer a commercial issue, they are a legal defence.
Who is responsible for keeping site records
Responsibility is shared, but accountability is clear.
During construction, the Principal Contractor carries primary responsibility for site records. The Principal Designer carries responsibility for design information and change control. Subcontractors are responsible for producing accurate installation, inspection and test evidence.
At handover, responsibility transfers to the Accountable Person, who becomes legally responsible for maintaining the Golden Thread.
On London projects with layered delivery teams, joint ventures and specialist packages, failure usually occurs at the interfaces, where information is produced but not controlled.
That is where most BSR compliance failures now occur.
How site teams should manage record retention in 2026
By 2026, paper files, unmanaged PDFs and fragmented document systems are no longer defensible. The Regulator expects structured digital information management aligned with Golden Thread principles.
That means:
Most Tier 1 contractors are now moving toward common data environments built specifically for BSR compliance rather than traditional document control. Site teams that still rely on ad-hoc filing systems are carrying significant regulatory risk.
The commercial reality for London projects
On London HRB projects, records retention now affects:
In effect, the building does not legally exist until the records prove that it does.
What this means for site managers and supervisors
Site managers are now information dutyholders. Every inspection, every test, every installation and every change must be recorded in a way that is auditable, traceable and legally defensible. The days of informal site notebooks and end-of-job compilation are over. Construction is now regulated like aviation, rail and nuclear. If it is not recorded, it did not happen.
Conclusion — records are now part of the structure
Under the Building Safety Act, construction site records are no longer paperwork. They are part of the building. They define whether the project can proceed, whether it can complete, whether it can be occupied and whether it can legally operate. On BSR-regulated projects, record retention is permanent, The Golden Thread does not close, it only grows.
On Higher-Risk Building projects, site records now form part of the statutory Golden Thread and are used by the Building Safety Regulator to assess whether a building can legally proceed through Gateway 2, reach completion at Gateway 3 and be safely occupied.
In London, where complex phasing, constrained logistics and multi-trade sequencing dominate delivery, record keeping has become one of the highest-risk compliance exposures on site.
If the records are missing, incomplete or unreliable, the project can be delayed, rejected or subject to enforcement action, regardless of whether the physical works are technically sound.
What counts as a construction site record under the BSA
Under the Building Safety Act, a construction site record is any information required to demonstrate that the building has been designed, constructed and commissioned in compliance with building regulations and the approved Gateway submissions.
This includes design information, construction records, inspection evidence, test results, change control documentation, competence records and handover information.
On BSR-regulated projects, records are no longer kept for convenience, they exist to prove regulatory compliance.
The Regulator treats these records as safety-critical data.
How long site records must be kept
There is no single retention period written into the Building Safety Act itself. Instead, record retention is defined through a combination of building safety law, building regulations, health and safety legislation, product liability law and the Golden Thread requirements.
In practice, this creates three overlapping time horizons.
1. Construction phase records
During construction, all site records must be retained in full for the entire duration of the project. This includes the full Gateway 2 to Gateway 3 period.
Nothing can be discarded while the building remains under regulatory control.
2. Gateway 3 and handover records
At completion, the Principal Contractor and Principal Designer must submit a complete, verified as-built information pack to the Accountable Person.
This becomes part of the statutory Golden Thread.
Once accepted by the BSR at Gateway 3, these records must be retained for the lifetime of the building.
3. Post-completion safety records
Once the building is occupied, the Accountable Person must maintain, update and preserve the Golden Thread for as long as the building remains in use.
There is no expiry date, if the building exists, the records must exist.
What lifetime of the building means in practice
The Golden Thread is a permanent legal obligation.
It must remain accurate, accessible, up to date and secure for the full operational life of the building, including refurbishments, material changes, remedial works and safety upgrades.
For most London residential towers, mixed-use developments and complex refurbishments, this means records must be retained for 60 to 100 years or more.
- If a building changes ownership, the records transfer with it.
- If the building is refurbished, the records must be updated.
- If an incident occurs decades later, the original construction records may be required as legal evidence.
What happens if records are missing or incomplete
The Building Safety Regulator treats missing records as a safety risk.
On live projects, missing records can result in Gateway delays, enforcement notices, construction stoppages or refusal of completion certificates.
On occupied buildings, missing Golden Thread data can trigger compliance investigations, improvement notices and criminal liability for dutyholders.
In the event of a serious incident, missing records may expose contractors, designers and dutyholders to prosecution under the Building Safety Act, the Health and Safety at Work Act and corporate manslaughter legislation.
Records are no longer a commercial issue, they are a legal defence.
Who is responsible for keeping site records
Responsibility is shared, but accountability is clear.
During construction, the Principal Contractor carries primary responsibility for site records. The Principal Designer carries responsibility for design information and change control. Subcontractors are responsible for producing accurate installation, inspection and test evidence.
At handover, responsibility transfers to the Accountable Person, who becomes legally responsible for maintaining the Golden Thread.
On London projects with layered delivery teams, joint ventures and specialist packages, failure usually occurs at the interfaces, where information is produced but not controlled.
That is where most BSR compliance failures now occur.
How site teams should manage record retention in 2026
By 2026, paper files, unmanaged PDFs and fragmented document systems are no longer defensible. The Regulator expects structured digital information management aligned with Golden Thread principles.
That means:
- Controlled document environments
- Version control
- Audit trails
- Change approval records
- Secure access management
- Permanent data preservation
Most Tier 1 contractors are now moving toward common data environments built specifically for BSR compliance rather than traditional document control. Site teams that still rely on ad-hoc filing systems are carrying significant regulatory risk.
The commercial reality for London projects
On London HRB projects, records retention now affects:
- Practical completion
- Building handover
- Occupation certificates
- Sales and lettings
- Investor sign-off
- Insurance
- Fire strategy approvals
- Mortgageability
In effect, the building does not legally exist until the records prove that it does.
What this means for site managers and supervisors
Site managers are now information dutyholders. Every inspection, every test, every installation and every change must be recorded in a way that is auditable, traceable and legally defensible. The days of informal site notebooks and end-of-job compilation are over. Construction is now regulated like aviation, rail and nuclear. If it is not recorded, it did not happen.
Conclusion — records are now part of the structure
Under the Building Safety Act, construction site records are no longer paperwork. They are part of the building. They define whether the project can proceed, whether it can complete, whether it can be occupied and whether it can legally operate. On BSR-regulated projects, record retention is permanent, The Golden Thread does not close, it only grows.
Image © London Construction Magazine Limited
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Expert Verification & Authorship: Mihai Chelmus
Founder, London Construction Magazine | Construction Testing & Investigation Specialist |
