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Since Grenfell, “high-risk building” has stopped being a loose description and become a defined legal category, with named duty holders, criminal sanctions and, several years on, real case law behind it. For every building still waiting on cladding remediation, someone has to keep residents safe in the meantime — and increasingly, that “meantime” means a temporary fire detection and alarm system rather than a waking watch rota. Get the specification, the sign-off or the maintenance wrong, and the question of who answers for it stops being theoretical very quickly. This article looks at what the Building Safety Act 2022 actually requires, what NFCC guidance says about interim protection, where fire designers, block management companies and installers tend to clash, and who the law says is ultimately accountable when something goes wrong.
By Ferdinand Anton - Principle Fire & Security Consultant
Under the Building Safety Act 2022, a higher-risk building (HRB) in England is one at least 18 metres tall, or with at least seven storeys, containing at least two residential units, subject to some exclusions. Part 4 of the Act introduces the role of the Accountable Person (AP) and, where a building has more than one, a Principal Accountable Person (PAP) who takes the lead. The AP must carry out and keep updated a risk assessment covering fire and structural safety, take all reasonable steps to prevent a building safety risk materialising, register the building with the Building Safety Regulator, and maintain the “golden thread” of information about the building’s design and construction.
Critically, this duty cannot be handed off. An AP can appoint a managing agent to handle the building day to day, but the legal accountability — and the exposure to criminal sanction if things go wrong — stays with the AP. That single point matters more than almost anything else in this article: whoever technically specifies, installs or maintains the fire alarm system, the AP remains on the hook for making sure it is adequate.
Cladding remediation is rarely fast. Where a building has been identified with non-compliant external wall systems — flammable ACM panels, missing cavity barriers, defective insulation — removal and replacement work often runs into years rather than months. Something has to protect residents while that work is ongoing, and that is where interim fire safety measures come in.
The default response has long been a “waking watch”: trained wardens patrolling the building around the clock to raise the alarm and support evacuation. It works, but it is expensive to sustain over a multi-year remediation programme, and industry reporting has put average remediation timescales at three to five years.
The National Fire Chiefs Council (NFCC) has been clear that where remediation is expected to take longer than 12 months, a temporary common fire alarm system is the safer and more cost-effective option. Alongside this, many affected buildings temporarily move from a “stay put” to a “simultaneous evacuation” strategy, meaning the alarm system needs to alert the whole building at once, rather than just the flat of origin as would be normal in a properly compartmented block.
NFCC guidance is specific about how a temporary system should be built, not just that one should exist. A common fire alarm system installed for this purpose should typically meet BS 5839-1 Category L5, designed around the specific risk the building presents rather than a generic template. It has to be installed, commissioned and then maintained to the same standard as a permanent system — the word “temporary” does not mean temporary rigour.
Getting from a waking watch (or nothing) to a working L5 system is not instant, either. It requires a fire risk assessment to confirm the switch is appropriate, a competent designer to specify the system around that building’s compartmentation and escape routes, and a contractor capable of installing and commissioning it to schedule. Government funding was introduced specifically to help buildings make this switch, on the logic that a properly specified alarm system pays for itself against the ongoing cost of 24-hour patrols.
This is the point where good intentions on paper turn into arguments on site. Three parties typically sit around the table for a temporary alarm installation on a cladding-affected building: the fire engineer or designer, who specifies the system based on the fire risk assessment; the block management company or managing agent, acting for the Accountable Person, who is paying for it and answering to leaseholders about cost and disruption; and the fire alarm contractor, who has to actually install, commission and maintain it.
Each party is working under a different pressure. The designer is focused on coverage, category and compliance with the fire risk assessment, and will be reluctant to compromise on detector placement or zoning just because access is difficult. The managing agent is focused on budget, leaseholder service charges, and how quickly sign-off can happen so waking watch costs stop accruing. The contractor is focused on what is actually installable in occupied flats, on what timescale, and who carries the risk if the design does not translate cleanly to site conditions.
Designs specified without a proper site survey, then found unworkable once installation starts
Management companies pushing for the cheapest compliant option rather than the most maintainable one
Unclear handover of who is responsible for ongoing servicing once the system is live
Vague scopes that leave the contractor exposed if a “temporary” system ends up staying in place for years
This is the question everyone in the chain wants answered before the ink dries on a contract, and the honest answer is: it depends what went wrong and when — but the Accountable Person cannot escape it entirely.
Under the Building Safety Act, the AP’s duty is non-delegable. Even where a managing agent has been appointed to handle the building day to day, legal responsibility for building safety risks — including inadequate interim fire protection — remains with the AP. Case law is starting to test how far liability extends beyond that. In Triathlon Homes LLP v Stratford Village Development Partnership, the Court of Appeal upheld a Remediation Contribution Order in July 2025 requiring the developer and its parent company to contribute roughly £18 million toward fire safety remediation — a clear signal that the courts are willing to look past corporate structure to reach the party that caused the problem.
More recently, in April 2026, the Technology and Construction Court granted Building Liability Orders against companies associated with contractor Ardmore Construction, in a case brought by developer Crest Nicholson over historic fire safety defects at a Portsmouth site. The contractor had entered administration the day before an adjudicator awarded Crest nearly £15 million over the defects; the court extended liability across the wider group rather than letting the debt disappear with the insolvent entity.
Both cases concern cladding and passive fire protection rather than a standalone active fire alarm failure — as of early 2026, no reported case has turned solely on a defective or poorly maintained interim fire alarm system. But the legal mechanism is the same one that would apply if it did: where a temporary alarm system installed as a “relevant step” under the Act failed because it was badly specified, badly installed or poorly maintained, Remediation Contribution Orders and Building Liability Orders give the courts a route to pursue whoever was actually responsible, however the corporate structure was arranged.
For contractors working on these projects, protection is not in staying quiet and hoping the AP absorbs the risk — it is in documentation and competency evidence that would hold up if a claim followed the AP’s own liability back down the chain.
A clear, written scope that ties the installed system to the fire risk assessment it is meant to satisfy
Evidence of BAFE SP203-1 or equivalent third-party certification for design, installation and commissioning
A documented handover specifying exactly who is responsible for ongoing servicing and testing once the system goes live
Contribution to the building’s “golden thread” record, rather than treating a temporary system as outside that requirement
Where the original design does not match site conditions, that should be raised and recorded formally rather than absorbed silently to keep the project moving. The paper trail showing a problem was flagged is worth far more after the fact than a system that quietly got installed anyway.
The direction of travel is clear: buildings will keep needing interim protection while cladding remediation continues, courts are increasingly comfortable assigning liability to whoever is actually responsible, and “we didn’t know” is a weaker defence with every year the Act beds in. For installers and engineers working in this space, competency and documentation are not paperwork exercises — they are the difference between being paid for good work and being drawn into someone else’s dispute.
LFS’s EAL Level 3 Award in Fire Detection and Alarm Systems, built around BS 5839-1:2025, is designed with exactly this level of accountability in mind.