The golden thread is the Building Safety Act’s requirement for an accurate, up-to-date and accessible record of building information, created and maintained digitally across the life of a higher-risk building: what was designed, what was built, and the evidence connecting the two.
It exists because the independent review of building regulations that followed the Grenfell Tower fire found that critical safety information was routinely lost, fragmented or wrong: buildings whose owners did not know what was in their own walls. The thread is the legal answer, resting on a simple idea: information about a building should be controlled as carefully as the building itself.
The duty applies to higher-risk buildings, broadly those at least 18 metres or seven storeys tall containing two or more residential units. The information must be held digitally, be accurate and kept up to date, be accessible to the people who need it, and be handed over as the building moves through its life: between dutyholders during design and construction, and to the accountable person once the building is occupied.
What goes into it is driven by purpose: the information needed to understand the building and keep its people safe. In practice that means design intent and its evolution, fire and structural safety information, the as-built record, changes made during construction and the decisions behind them, test and commissioning evidence, and the competence trail of the people who did the work.
The gateway regime enforces it. Gateway 2 approval is granted on a defined body of information, controlled and notifiable changes during construction must be recorded and in some cases approved before proceeding, and gateway 3 asks whether what was built matches what was approved, with the evidence to show it. A project that captures evidence as work proceeds arrives at gateway 3 with a record; one that does not arrives with a reconstruction.
Although the strict duty sits on higher-risk buildings, the working method reaches further. Subcontractors feed the thread whether or not they ever read the Act, because the principal dutyholders can only hand over what was captured on site in the first place. The practical discipline is unglamorous: dated records, controlled changes, photographs of work before it is covered up, filed somewhere they can be found in thirty years.
Construction Metric’s Building Safety Act page sets out how a record built automatically from site WhatsApp traffic supports the golden thread without adding paperwork to site.