Retrofitting Smoke Control Without Decanting Residents

A block of 60 flats, one stair, an AOV at the head of the stair, and a control panel from 2004 that nobody can get parts for. The fire risk assessment has flagged it. The landlord wants it fixed this financial year. Nobody is moving out while it happens.

That is the normal condition for smoke control retrofit in UK housing, not the exception. Decanting residents to replace a life safety system in the common parts is almost never proportionate and almost never affordable, so the work happens around people. Which means the hard part of the job is not choosing the products. It is sequencing, because the system protecting the escape route has to keep protecting it while it is being taken out.

Why the Retrofit Landed on Your Programme

Smoke control retrofits rarely start with someone deciding to improve the building. They start with a document.

A fire risk assessment action. The assessor has flagged the system as unproven, undocumented, or non-functional and put a date against it. This is the single most common trigger in housing stock.

A failed test. The monthly check or the annual service found vents that will not open, a panel in permanent fault, or batteries that will not hold the system up. See Your Smoke Ventilation System Failed Its Last Test. What Now? for the immediate steps.

Obsolescence. Panels from the early 2000s are past their service life, and once the manufacturer stops making the PCB, a £200 fault becomes a panel replacement by necessity rather than by choice.

Statutory pressure. In high-rise residential buildings, regulation 7 of the Fire Safety (England) Regulations 2022 requires monthly routine checks of essential fire-fighting equipment, which includes smoke control, and faults that cannot be rectified within 24 hours have to be reported to the fire and rescue authority. A system that cannot pass a monthly check generates a reportable fault every month it stays broken. Article 17 of the Regulatory Reform (Fire Safety) Order 2005 sits underneath that for every other building, requiring fire safety equipment to be kept in efficient working order under a suitable system of maintenance.

Building Safety Act evidence. For higher-risk buildings, the accountable person has to be able to show what is installed, how it was configured and how it has been maintained. A dip-switch panel with a handwritten logbook does not produce that evidence. The Golden Thread and Smoke Ventilation covers what the record has to contain.

Post-Grenfell remediation. Where a block is already in a remediation programme for cladding or compartmentation, smoke control usually comes into scope with it, because the fire strategy is being revisited anyway.

The Sequencing Problem

Here is what makes an occupied retrofit different from a new build fit-out. On a new build, nothing is protecting anything yet. On a retrofit, the building’s means of escape depends on the system you are about to remove, and it depends on it continuously, not on working days between 8am and 5pm.

So “switch the old one off, install the new one, switch it on” is not available as a method statement. What you plan instead is a series of short, controlled outages, each one covered by something, with the system live either side.

The single most useful decision on a retrofit is made before anyone lifts a tool: how small can the outage be made? A first fix that pulls new cable alongside the existing installation, leaving the old system running until the day of the changeover, is worth paying for. Ripping out cable on day one and leaving the building on a fire watch for three weeks generates complaints, reportable faults and an unhappy fire risk assessor.

Regulation 7 bites on faults rather than on planned work, and a properly notified, properly covered outage is not a fault. That distinction gets thin the moment a planned outage overruns. If the system is out of service past the window that was agreed, treat it as a fault and report it. The alternative is an enforcement conversation about whether a two-week “planned” outage was really planned.

Survey First, Price Second

You cannot price this job honestly from a photograph of the panel. The survey is where the scope is decided, and the survey has to cover the whole system, not the box on the wall.

What has to come back from site:

• Every vent, with its make, model and evidence. Does it open fully? Is there a Declaration of Performance showing certification to BS EN 12101-2, and does its declared aerodynamic free area match what the fire strategy asks for?
• Every actuator. Type, voltage, stroke, condition, and whether the fixings and brackets are reusable.
• Every damper and fan, where the system is a shaft or a mechanical one, with fire ratings evidenced.
• The cabling. Type, fire resistance rating, route, condition, and whether it can be reused or has to be replaced. This is the item that most often decides between a one-night job and a six-week one.
• The fire alarm interface. How the signal arrives, whether it is monitored, and who owns the alarm system.
• The existing cause and effect. Which detector drives which vent, in what order, with what delays and what lockout logic.
• Access. Roof access arrangements, riser cupboard keys, whether any part of the system passes through a private flat.

Two of those deserve more attention than they usually get. The first is the cause and effect. On a system that has been in service for fifteen years with undocumented modifications, what is programmed into the panel and what is written in the original design are frequently different things. Record what the panel actually does before you remove it, because that is the only surviving copy. Cause and Effect Matrices Explained covers how to write it up properly.

The second is documentation you do not have. If the building has no asset register, build one as part of the survey rather than after the work. How to Build a Smoke Control Asset Register from Scratch sets out the method. You will need it for the handover anyway, and building it first is what stops the scope moving twice.

What Turns a Like-for-Like Swap Into a Redesign

A like-for-like swap replaces failed equipment with certified equivalent equipment in the same positions, driven by the same logic. It is fast, cheap and defensible, and it is available more often than people assume, because the vent positions in most residential blocks were set by the original code-following design and have not moved.

It stops being available the moment the existing system does not do what current guidance expects. The triggers:

Where the answer is redesign, treat it as a new smoke control design with the existing building as a constraint, not as a bigger version of a panel swap. From Fire Strategy to Smoke Control Specification is the route through that. And check early whether the work is notifiable building work. In a higher-risk building, the Building Safety Regulator is the building control authority and the gateway process applies, which changes the programme considerably. Building Safety Act Gateways 2 and 3 covers what that involves.

Honest caveat: the boundary between swap and redesign is not always obvious, and it is a fire strategy judgement rather than a product one. If the survey turns up a shortfall, that is a conversation with the fire risk assessor or fire engineer before it is a conversation with a supplier.

Interim Measures, and Who Actually Agrees Them

Contractors do not decide interim measures. The responsible person does, informed by the fire risk assessment, and the assessor should have sight of anything that changes how the building behaves in a fire.

For a short changeover window in a building where the vents can still be operated manually and the stair is otherwise sound, the measures are usually modest: a fire watch or increased vigilance during the window, residents notified, a clear escalation route, and the window kept short. For a longer outage, or a building already carrying other fire safety defects, the measures escalate, and the decision to move a stay-put block to simultaneous evacuation is a fire strategy change, not a site decision. That belongs in the fire risk assessment, and the fire and rescue service should know about it.

Whatever is agreed, write it down before the work starts, with a named person, a start time, an end time and a removal trigger. Interim measures that nobody records tend to become permanent by accident, and interim measures that nobody removes cost money for years.

Two points that get missed. Tell the alarm receiving centre before the first isolation, or the first test call generates an unwanted fire and rescue attendance. And confirm who is holding the fire watch overnight, because “the contractor’s engineer is on site anyway” is not a fire watch.

Working in a Live Building

The physical work in an occupied block is constrained less by engineering than by people.

Work zone by zone, or stair by stair. On a networked system this is straightforward: one zone comes out, the rest stay live, and the exposure is one floor rather than the building. On a single-panel single-stair block there is only one zone, which is exactly why the changeover window matters so much there.

Out-of-hours windows cut both ways. Evening and overnight working keeps the corridors clear and shortens the period when residents are moving through the work area. It also brings noise complaints, lone working arrangements, poor light for roof work, and engineers making decisions at 3am with nobody to call. Roof vent replacement in particular is a daylight and weather job. Leaving a roof opening temporarily weatherproofed overnight is a risk decision, not a default.

Access is the programme risk. Roof hatches, riser cupboards, plant room keys, and any part of the route that passes through a private flat. Confirm all of it during the survey. A missing key on the night of a changeover is how a planned outage becomes an unplanned one.

Tell residents properly. A notice on the door two days before is not communication. What works is a letter that says what is being done, why, which nights the work runs, what noise to expect, and what to do if the alarm sounds during testing. Residents who understand that the vent above the stair is a fire safety system generate far fewer complaints than residents who see scaffolding and a hole in the roof and draw their own conclusions.

Reduce the time the panel is off the wall. A panel that arrives pre-configured to an approved cause and effect matrix, needing only termination and proving on site, takes far less time out of service than one configured from scratch in a plant room. A pre-configured addressable panel reusing existing wiring can often be swapped inside a single out-of-hours window, subject to what the survey finds. Addressable equipment helps here for a specific reason: our own O Range holds its configuration in software rather than on dip switches, so the setup is prepared and checked before it reaches site, and every event and change is logged for the building record.

Commissioning and Witness Testing With the Building Occupied

Commissioning is where retrofits get quietly compromised, because full testing in an occupied building is inconvenient and partial testing looks similar on paper.

It is not similar. Every input and every output has to be proved against the approved cause and effect, floor by floor, not only on the ground floor or the zone the engineer happened to be standing in. Detector activation, vent open and close through full travel, damper operation, fan start and run where fitted, the fire alarm interface under a real signal rather than a simulated one, the firefighter override, battery standby and the fault monitoring.

What the occupied setting adds:

• Notify residents, the alarm receiving centre and any on-site staff before testing, and again when testing finishes.
• Agree whether sounders are isolated during the test, and if they are, prove the alarm interface separately so the chain is still tested end to end.
• Where smoke or aerosol testing is used, plan for the smell and the questions that follow it.
• Schedule the test for a time when the building can tolerate it, then hold that slot. Testing that gets shortened because it is late is testing that gets repeated.

Witness testing by the client, the fire risk assessor or the building safety manager is worth arranging on retrofits specifically. Otherwise the person signing the building safety case is relying entirely on the contractor’s own certificate for a system they never saw operate. Our commissioning page and Commissioning Best Practices for Smoke Ventilation Systems cover the step-by-step detail.

The Handover Records That Make the Retrofit Defensible

A retrofit is only as defensible as the pack it produces. Years later, nobody remembers the site conditions or the reasoning. They read the file.

What the responsible person should receive, and should refuse to close the job without:

• The updated and approved cause and effect matrix, matching what is programmed
• Commissioning certificates covering every zone, with results rather than ticks
• Declarations of Performance for every product installed, not just the panel
• An updated asset register, with the superseded entries retained rather than overwritten
• O&M manuals, and the operator’s manual the monthly check has to be carried out against
• Photographs of the wiring before and after, and of anything concealed
• A revised maintenance schedule reflecting what is now installed
• Written confirmation that interim measures have been removed, with the date
• Evidence of compliant WEEE disposal of the old panel and batteries

For higher-risk buildings, all of that feeds the golden thread and the building safety case rather than sitting in a folder. Where the work was notifiable building work, regulation 38 fire safety information applies at completion as well. Smoke Control Handover Documents at Practical Completion covers what a complete pack looks like.

One habit worth adopting: record the interim measures period in the building’s fire safety record too, with start and end dates and what was in place. If anyone ever asks how the escape route was protected during the works, that is the answer, and it is very hard to reconstruct after the fact.

Practical Takeaway

Survey the whole system before you price anything, and record what the existing panel actually does before you remove it. Decide early whether you are swapping like for like or redesigning, and make that a fire strategy decision rather than a procurement one. Plan the outage to be as short and as small as the building allows, first fix alongside the live system where you can, and work zone by zone where the system permits. Get interim measures agreed and written down by the responsible person before anyone isolates anything, with a removal date. Pre-configure the panel off site. Commission in full, with the client watching. Then hand over a pack that will still answer the question in ten years, because that is the part of the job that gets tested long after the engineers have left.

Further Reading

• Replacing an Old Smoke Control Panel: What to Check
• How to Build a Smoke Control Asset Register from Scratch
• Cause and Effect Matrices Explained
• Smoke control for housing associations
• Commissioning

Sources

Official guidance and standards referenced in this article:

• The Fire Safety (England) Regulations 2022, regulation 7, legislation.gov.uk
• Regulatory Reform (Fire Safety) Order 2005, legislation.gov.uk
• Building Safety Act 2022, legislation.gov.uk
• Approved Document B (fire safety), GOV.UK
• BS 9991:2024, BSI Knowledge
• Smoke Control Association

Planning a Retrofit in an Occupied Block?

We supply smoke control panels, stairwell AOVs and actuators for UK retrofit work, with stock held in Poole and next-working-day despatch on most lines. Our technical team can review a survey and tell you honestly whether the job is a swap or a redesign before you commit to a programme.

Call 01202 725 689 or email info@vent-trade.co.uk.