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Fire safety legislation

The Building Safety Act and the Golden Thread, explained

Explainer 9 min read Reviewed Tom Ford, Founder

The Building Safety Act 2022 is UK law requiring owners of higher-risk buildings to prove, with a Golden Thread of records, that fire and structural risks are managed.

This page is written for the people the Act makes responsible. It covers what counts as a higher-risk building, who holds which duty and when, what the Golden Thread has to contain, and what all of it means for the firestopping hidden behind your walls.

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The threshold, drawn

What is a higher-risk building?

Under the Building Safety Act 2022, a higher-risk building (HRB) is generally a building at least 18 metres tall or with at least seven storeys, containing two or more residential units. Cross that line and a stricter regime applies at every stage of the building's life. Below it, fire safety duties still bite. The Golden Thread and the Gateways do not.

A section through a residential building. A metre rule runs up the left-hand side from zero to 24 metres. Storeys are stacked from ground level upward, and the seventh storey and everything above it are highlighted, with a marked threshold line at 18 metres and seven storeys. Beneath the drawing, the building's life runs left to right through Gateway 1 at planning, Gateway 2 before construction starts, and Gateway 3 at completion, naming the dutyholder responsible at each stage.

Height test 18 m or 7 storeys Whichever is reached first. The measurement is what puts a building inside the regime, not its age or its use.
And it contains 2+ residential units In occupation. During design and construction the same height test also captures hospitals and care homes.
Below the line Duties, without the Gateways Below the 18-metre or seven-storey higher-risk threshold, a separate regime starts at 11 metres or five storeys, covering the leaseholder protections and additional checking duties in common parts. Those are real obligations. They do not trigger the Gateways or the Golden Thread.

Along the building's life: who answers for it at each stage

1 Gateway 1 · Planning Fire safety is considered at the planning application, before the design hardens. Held by the client and Principal Designer
2 Gateway 2 · Before build The hard stop. The Building Safety Regulator checks the design meets building regulations before construction can start. Held by the Principal Designer and Principal Contractor
3 Gateway 3 · Completion The building is signed off and registered before anyone moves in, and the record is handed on. Passes to the Accountable Person

The Golden Thread runs underneath all three. It starts at design, is added to as the building is built, and is maintained for as long as people live there.

Dutyholders

What are dutyholder duties for compartmentation?

The Building Safety Act assigns named dutyholders, including the Accountable Person in occupation and the Principal Contractor and Principal Designer during construction. For compartmentation, their duty is to ensure the fire-separating line is designed, installed and maintained correctly, and to hold the information that proves it. That means keeping records of firestopping systems, product data and inspections in the Golden Thread, and being able to produce them for the Building Safety Regulator. Where records do not exist, an Intrusion Survey establishes the current position. Duties are ongoing, not a one-off sign-off, so the Golden Thread must be kept current as the building changes.

What is a dutyholder, and when does the duty transfer?

A dutyholder is a named party the Act makes legally responsible for a defined part of building safety. The point people miss is that the role moves. It is held by one set of people while the building is being designed and built, and by a different person once residents are living in it. Each handover is a moment where information gets lost, and the Act is written to stop exactly that. Whoever holds the duty has to be able to produce the record on request.

PD Principal Designer Owns the design of the fire-separating line and the specification behind it. Where a tested system is swapped for something else, the design liability lands here.
PC Principal Contractor Owns what is actually built. Every penetration, joint and cavity has to match the system that was tested, and the proof has to be captured before the wall closes over it.
AP Accountable Person Takes the building on in occupation, inherits the record, and keeps it current through every refurbishment, riser alteration and cable pull for the life of the building.

Who is the Building Safety Regulator?

The Building Safety Regulator is the body the Act created to oversee higher-risk buildings, and it sits within the Health and Safety Executive. It does three things that matter to anyone delivering firestopping. It runs the Gateways, so it can stop a scheme before construction starts. It keeps the register of occupied higher-risk buildings, so it knows which ones exist and who is accountable for each. And it can ask to see the evidence. That last power is the one that changes behaviour on site. A regulator that can request the record for any penetration in the building is a regulator that makes reconstructing paperwork afterwards a bad strategy. The realistic planning assumption is that you will be asked at the least convenient moment, and the record will either be there or it will not.

Recorded on site
Tagged before cover-up A riser penetration, photographed and tagged before it was closed over.
The record

What does the Golden Thread have to contain?

The Golden Thread is the accurate, current record of a building's safety information, held so that the people responsible can find it and act on it. For firestopping that means more than a folder of certificates. It means knowing which tested system went into which hole, on which floor, on what date, installed by whom, with the photograph that shows it before the ceiling went back up. Anyone can produce paperwork after the fact. A record made as the work went in is the one that survives scrutiny.

  • Tested systems, never mixed The system installed matches the system that was tested, with no substitutions and no site decisions on safety-critical seals.
  • Evidenced before cover-up Every penetration, joint and cavity photographed before, during and after installation, then tagged, batch-traced and geo-located.
  • Captured as installed The record enters the Golden Thread as the work goes in, never reconstructed afterwards from memory or from a supplier's spec sheet.
  • Retained for 15 years A complete evidence pack at handover, held for the full liability window, with mandatory occurrence reporting built into quality assurance.

What is Gateway 2 and what evidence does it need?

Gateway 2 is the hard stop before construction of a higher-risk building can start, where the Building Safety Regulator checks that the design meets building regulations. Firestopping and compartmentation evidence forms part of the case that has to satisfy it. In practice the Regulator is testing whether the compartmentation strategy is deliverable as drawn: whether each penetration has a tested system behind it, whether the details resolve, and whether anyone has quietly value-engineered a tested detail into an untested one. A submission that cannot answer those questions comes back as a request for further information, and the programme waits. That is what a Gateway 2 evidence pack is for.

What happens when the records do not exist?

Most buildings that need a Golden Thread today were built before anyone was keeping one. The gap is normal. What matters is establishing the current position honestly, and an Intrusion Survey is how that is done: floor by floor, every breach in the fire-rated walls, floors and risers identified, photographed, located and validated against the fire strategy. From there the record has a starting point. Remediation can be prioritised by risk rather than by guesswork, and the dutyholder has something defensible to put in front of a regulator, an insurer or a court.

I was there the morning Grenfell burned. I couldn't help them. So now I make sure the work hidden behind the wall never fails the people who can't see it.
Tom Ford Founder, Skyline Firestopping · Making our cities safer
Straight answers

Building Safety Act questions, answered

What is the Building Safety Act 2022?

It is the UK law that reforms the safety of higher-risk buildings after Grenfell. It creates the Building Safety Regulator, names dutyholders accountable for safety, and requires a Golden Thread of records proving fire and structural risks, including compartmentation, are managed.

What is a higher-risk building?

Generally a building at least 18 metres or seven storeys tall with two or more residential units. These buildings fall under the Building Safety Regulator and must keep a Golden Thread of safety information across design, construction and occupation.

What is Gateway 2?

Gateway 2 is the hard stop before construction of a higher-risk building can start, where the Building Safety Regulator checks that the design meets building regulations. Firestopping and compartmentation evidence forms part of the case that has to satisfy it.

Who is the dutyholder for fire compartmentation?

During construction the Principal Contractor and Principal Designer hold duties; in occupation the Accountable Person does. Each must ensure compartmentation is correct and hold the records that prove it in the Golden Thread.

What is a dutyholder under the Building Safety Act?

A dutyholder is a named party the Act makes legally responsible for a defined part of building safety. The role moves with the building's life. The Principal Designer and Principal Contractor hold it while the building is designed and built, and the Accountable Person holds it once people live there.

What buildings are higher risk?

In occupation, buildings of at least 18 metres or seven storeys containing two or more residential units. During design and construction the same height test also captures hospitals and care homes. Below that line a separate regime begins at 11 metres or five storeys, governing the leaseholder protections and additional checking duties in common parts. It does not bring a building inside the Gateways or the Golden Thread.

Who is responsible for enforcing fire safety?

More than one body enforces it. In existing buildings, the Regulatory Reform Fire Safety Order 2005 puts the duty on a 'responsible person', policed by local Fire and Rescue Authorities and backed by the Fire Safety Act 2021. In a higher-risk building, the Building Safety Regulator (part of the Health and Safety Executive) takes over: it runs the Gateways and can demand the Golden Thread record under the BSA 2022.

What other fire building regs apply, besides the Building Safety Act?

Two more sit alongside it, and together with the Building Safety Act they make up the fire safety legislation a firestopping contractor has to satisfy. Approved Document B, under the Building Regulations 2010, sets the technical fire-safety standard a design has to meet: compartmentation, means of escape and fire-resisting construction. The Regulatory Reform Fire Safety Order 2005 covers day-to-day fire safety management once a building is occupied. Firestopping sits where all three meet: the design standard, the ongoing duty and, for higher-risk buildings, the Golden Thread evidence. Our passive fire protection guides cover each regime in more depth.

Written and reviewed by Tom Ford, founder of Skyline Firestopping. Last reviewed . Building safety law changes often; the date above shows when this page was last checked against it.

Put it into practice

Check your Golden Thread readiness

The free guide, The Golden Thread Explained, covers what the Act asks of a dutyholder’s records and how to check your own firestopping paperwork against it. From Skyline Firestopping, a BM TRADA Q-Mark-certified installer.
Check your golden thread readiness → Read the FAQ
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