What Causes Warehouse Fires — and How to Prevent Them
Warehouse & Industrial Fire Safety
Warehouse fires are among the most destructive incidents any business can face. Understanding the underlying causes — from arson and electrical faults to spontaneous combustion and automated system failures — is the first step toward meaningful prevention.
Every year, warehouse and industrial premises across the UK are seriously damaged or destroyed by fire. Some incidents make national headlines; many do not. What they share, almost without exception, is a combination of combustible materials, ignition sources, and fire safety arrangements that were either absent, inadequate, or simply not maintained.
The consequences extend well beyond the building itself. Stock is lost. Supply chains are disrupted. Neighbouring businesses suffer. Communities breathe toxic smoke for days. And in the aftermath, investigations frequently reveal that the fire was preventable, or at least that its spread could have been significantly limited.
This article examines the principal causes of warehouse fires in the UK, illustrates each with recent real-world incidents, and sets out what responsible persons and facilities managers can do to reduce the risk. For those with legal duties under the Regulatory Reform (Fire Safety) Order 2005, the starting point is always a competent fire risk assessment — but that is very much the beginning, not the end.
Why Warehouses Are Particularly Vulnerable
Before examining specific causes, it is worth understanding what makes warehouse environments inherently challenging from a fire safety perspective. The combination of factors is rarely found elsewhere in the built environment to the same degree.
Large, open-plan floor plates mean that a fire, once established, can spread rapidly across an entire building with little or no compartmentation to slow it. High-bay racking concentrates combustible stock in vertical columns, creating conditions in which heat and flame travel upward with exceptional speed. Loading bays and goods-in areas are transitional zones where fire doors are frequently left open, vehicles bring in external ignition sources, and stock sits unprotected while awaiting processing. Shift patterns, lone working, and unmanned overnight periods mean that early detection is not always possible.
Cold store and refrigerated warehouse environments introduce additional complexity, including flammable refrigerants, polyurethane foam insulation panels, and condensation-related electrical issues. Recycling and waste-handling facilities carry their own distinct hazards, not least the spontaneous combustion of certain stored materials.
Against this backdrop, the causes of warehouse fires fall into several broad categories.
Arson
Arson is one of the leading causes of fire in commercial and industrial premises in the UK. Warehouses are attractive targets: they are often located on the periphery of urban areas, screened from public view, unmanned at night, and packed with combustible materials that provide ready fuel. A fire started deliberately at the perimeter of a building, or within a waste skip adjacent to an external wall, can take hold before any alarm is triggered.
The risk is not limited to large facilities. Smaller units on industrial estates, with poor perimeter security and limited CCTV coverage, are frequently targeted. The motive can be financial — insurance fraud is a well-documented driver — but arson is also committed opportunistically, by former employees, or as part of wider criminal activity.
Reducing arson risk requires a combination of physical security measures and management controls: perimeter fencing and lighting, secure compound areas for waste and recycling, CCTV coverage of external elevations, and clear procedures for reporting suspicious activity. None of these are substitutes for a properly conducted fire risk assessment, which will identify site-specific arson vulnerabilities and recommend appropriate controls.
Case Study — Arson
Kimberly-Clark Warehouse Fire, April 2025
On 7 April 2025, a large Kimberly-Clark warehouse storing paper products was deliberately set alight in what investigators confirmed was an arson attack. The footage from the scene shows the speed at which fire can spread through a building containing large volumes of paper-based stock — a highly combustible load, stored at scale, in a building designed for density and throughput rather than fire containment.
The incident illustrates several arson risk factors that are common to large warehouse operations: high-value combustible stock, a building footprint too large for rapid manual detection, and the particular vulnerability of paper and cardboard storage to fast-developing fire. It also serves as a reminder that arson is not an abstract risk; it is a frequent cause of major commercial fires, and the question of how to harden a site against deliberate ignition is one that any responsible person should be asking.
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Footage from the Kimberly-Clark warehouse fire, April 2025, which investigators determined was caused by arson.
Electrical Faults and Equipment Failure
Electrical faults account for a significant proportion of accidental warehouse fires. The scale and intensity of electrical infrastructure in a modern distribution or fulfilment centre — conveyor systems, automated machinery, charging stations, racking-mounted lighting, refrigeration plant, and building management systems — creates numerous potential ignition points, any one of which can trigger a catastrophic fire if not properly maintained and monitored.
The shift toward automation has introduced new categories of risk. Robotic picking systems, automated guided vehicles, and conveyor networks operate continuously and generate heat. Battery charging for electric forklift trucks is a well-documented cause of fire; lithium-ion technology, now widely deployed, introduces additional hazards that older risk assessments may not have addressed. Faulty wiring in older buildings, combined with the demands placed on electrical systems by high-density modern operations, is another recurrent factor.
Regular inspection of fixed wiring installations, adherence to manufacturer maintenance schedules for equipment, and appropriate segregation of charging areas from stored stock are among the measures most likely to reduce electrical fire risk. The need for fire risk assessments to be updated when operations change — and automated warehouse technology certainly constitutes a change — cannot be overstated.
Case Study — Automated Systems and Electrical Risk
Ocado Automated Warehouse, Andover (February 2019)
In February 2019, a fire at Ocado's highly automated Customer Fulfilment Centre in Andover, Hampshire, resulted in the near-total destruction of the facility. The building housed a grid-based robotic picking system in which hundreds of autonomous robots operated simultaneously, charging wirelessly as they moved. Investigators identified the fire as starting within the robotic grid, most likely due to an electrical fault involving one of the charging robots.
The fire presented firefighting crews with exceptional difficulties. The dense robotic infrastructure made interior access dangerous. The scale of the building, combined with the volume of combustible packaging materials stored within the grid, meant the fire spread rapidly before it could be contained. The facility, which had been designed with considerable engineering sophistication, was nonetheless destroyed.
The Andover fire was significant not just because of its scale, but because of what it revealed about the fire safety challenges inherent in highly automated warehouse environments. The technology that makes such facilities efficient — continuous operation, dense stock placement, wireless charging across large floor areas — also creates fire risks that require specific assessment and specific mitigations. A standard fire risk assessment template designed for a conventional warehousing operation is unlikely to be adequate for a facility of this type.
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The Ocado automated warehouse fire in Andover, February 2019, demonstrated the specific fire risks associated with large-scale robotic fulfilment centres.
Spontaneous Combustion
Spontaneous combustion occurs when a material generates heat through chemical or biological oxidation processes, and that heat accumulates to the point of ignition without any external ignition source. It is a risk that is easy to underestimate, because there is no obvious trigger event — no electrical fault, no discarded cigarette, no deliberate act. The fire simply begins, typically within a pile or stockpile of material, and may smoulder for hours before breaking out into open flame.
The materials most susceptible to spontaneous combustion in a warehouse or industrial context include: waste paper and cardboard in large quantities; organic materials undergoing biological decomposition; oily rags and cloths left in storage; coal, biomass, and biofuels; and certain categories of processed plastic and mixed recyclate. Factors that increase the risk include high ambient temperature, poor ventilation, compression of materials within stockpiles, and the presence of moisture, which can accelerate biological degradation.
Recycling and waste-handling facilities carry a particularly elevated spontaneous combustion risk, as they typically store large volumes of mixed organic and plastic material, often outdoors or under cover rather than in fully enclosed fire-compartmented buildings. The fire risk assessment for such facilities should reflect this, with specific controls around stockpile height and depth, temperature monitoring, housekeeping regimes, and the management of materials awaiting processing.
Case Study — Spontaneous Combustion
Monoworld Recycling Warehouse, Rushden (May 2025)
At approximately 6.30am on 23 May 2025, fire broke out at the Monoworld Recycling warehouse on the Sanders Lodge Industrial Estate in Rushden, Northamptonshire. Monoworld is a large plastic waste reprocessor, handling plastic packaging for recycling and export. The fire spread rapidly through stockpiles of processed plastic, generating a massive plume of black smoke visible from as far away as Bedfordshire and Cambridgeshire. Northamptonshire Fire and Rescue Service declared a major incident; at the height of the blaze, twelve fire crews were deployed, along with aerial appliances and high-volume pumps. Neighbouring premises were evacuated and the gas supply to the entire industrial estate was isolated.
Following investigation, Northamptonshire Fire and Rescue Service determined the cause as accidental: spontaneous combustion of a viable ignition source, though the precise source of the initial ignition could not be identified. The site continued to smoke for more than a week after the fire was contained, with crews attending to monitor temperatures and dampen residual hotspots.
The aftermath has prompted significant local scrutiny of the site's fire safety arrangements. When Monoworld subsequently sought planning permission to rebuild a storage canopy, a local councillor called for conditions requiring a detailed fire prevention plan, fire suppression infrastructure, and strict controls on storage and material handling, citing the need to ensure planning conditions addressed safety given the site's history. The incident is a clear illustration of the particular vulnerability of plastic recyclate to spontaneous combustion, and of the community consequences that can result from a major fire at an industrial recycling facility.
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The Monoworld Recycling warehouse fire, Rushden, May 2025. Investigators found the cause to be spontaneous combustion, generating a smoke plume visible across three counties.
Hot Work and Maintenance Activities
Hot work — welding, cutting, grinding, and similar activities — is a disproportionate cause of warehouse fires, particularly because it is often carried out by contractors in environments they are unfamiliar with, without adequate controls. The risk is well understood in theory, but poorly managed in practice on many sites. Sparks and spatter from grinding or cutting can travel several metres and ignite combustible materials that are nowhere near the work itself. Structural members, roof timbers, and wall cavities can smoulder for hours before a fire becomes apparent.
A hot work permit system is the standard control, and it is not complex: before any hot work is carried out, a responsible person should assess the area, remove or protect combustible materials within the exclusion zone, confirm that fire extinguishers are immediately available, and establish a fire watch both during the work and for at least an hour after it concludes. In practice, many incidents occur because one or more of these steps is omitted, particularly the post-work fire watch.
Contractors working on site should be subject to the same controls as directly employed staff. A fire risk assessment that identifies hot work as a planned activity should include specific procedures, and those procedures should be communicated to and understood by everyone involved before work begins.
Hot work is responsible for a significant number of serious warehouse fires each year, and the majority occur not during the work itself but in the hours after it concludes, when smouldering material in a cavity or void breaks into open flame. A one-hour fire watch after completion is not optional.
Smoking, Human Error, and Poor Housekeeping
Not all warehouse fires have dramatic or technically complex origins. A significant number are caused by straightforward human error: a discarded cigarette near a loading bay, a pile of cardboard left adjacent to an electrical panel, waste accumulation in areas that are neither routinely inspected nor maintained. Smoking in prohibited areas, or in designated areas where waste material has been allowed to accumulate nearby, remains a recurring cause.
Housekeeping is not a peripheral fire safety concern; it is a central one. Combustible waste — cardboard, packaging film, pallets, paper — should be removed from the building or placed in appropriate external storage regularly, and not allowed to accumulate overnight. The area around electrical switchgear, distribution boards, and plant rooms should be kept clear at all times. Fire escape routes and fire door corridors should not be used as overflow storage, however temporarily.
These are not difficult controls to implement, but they require consistent management attention and clear accountability. A site where housekeeping standards are poor is a site where other fire safety controls are also likely to be under pressure.
Lithium-Ion Batteries and Charging
The proliferation of lithium-ion battery technology in warehouse operations — electric forklift trucks, autonomous mobile robots, handheld scanning devices, and fleet vehicles — has introduced a fire risk that is qualitatively different from most others. Lithium-ion fires burn intensely, are extremely difficult to extinguish with conventional firefighting media, and can reignite hours or even days after appearing to be under control. Thermal runaway, in which a cell failure triggers a self-sustaining chemical reaction generating enormous heat, can develop with little warning.
The risk is heightened during charging, but is not limited to it. Batteries that have been mechanically damaged — by a forklift impact, for instance — may not immediately show signs of failure but can develop internal faults that manifest as a fire hours later. Batteries that are aged or have been subjected to deep discharge cycles are similarly at elevated risk.
Good practice in lithium-ion battery management includes: dedicated, fire-compartmented charging areas with appropriate detection and suppression; regular inspection of battery condition; clear procedures for handling and reporting impact damage; and fire risk assessments that specifically address lithium-ion storage and charging. For operations where lithium-ion technology is a recent introduction, a review of the existing fire risk assessment is strongly advisable.
Key Causes at a Glance
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1ArsonOne of the leading causes of commercial fire in the UK. Warehouses on industrial estates with poor perimeter security are particularly vulnerable. Controls include lighting, CCTV, secure waste storage, and access management.
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2Electrical FaultsFaulty wiring, overloaded circuits, and failures in automated systems or charging infrastructure. Fixed wiring inspection, equipment maintenance schedules, and updated risk assessments when operations change are the primary controls.
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3Spontaneous CombustionParticularly relevant to recycling, waste-handling, paper storage, and biomass operations. Controls include managing stockpile height and depth, temperature monitoring, and regular material turnover.
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4Hot WorkWelding, cutting, and grinding by contractors and directly employed staff. A robust hot work permit system and mandatory post-work fire watch are the critical controls.
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5Lithium-Ion BatteriesIncreasingly significant as electric vehicle and robotic technology becomes standard. Dedicated charging areas, impact damage protocols, and battery condition monitoring are essential.
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6Poor HousekeepingCombustible waste accumulation, inappropriate storage near ignition sources, and smoking in prohibited areas. Consistent management standards and clear accountability are required.
Prevention: What Good Fire Safety Looks Like in Practice
Prevention in a warehouse environment is not a single measure; it is a layered system in which physical controls, management procedures, staff training, and formal documentation work together. Any one of those layers, taken in isolation, is insufficient. A site with excellent physical infrastructure but no staff training will not respond appropriately when the infrastructure fails. A site with well-trained staff but no systematic inspection regime will not catch the gradual deterioration of fire doors or the slow accumulation of combustible waste in overlooked corners.
The following measures represent the baseline for a well-managed warehouse fire safety regime.
- Maintain an up-to-date fire risk assessment. The assessment should be specific to the site and the operations conducted, reviewed whenever operations, occupancy, or layout changes significantly, and — as a minimum — reviewed annually. A competent fire risk assessment is a legal requirement under the FSO, not an optional extra.
- Ensure fire detection and alarm systems are appropriate to the risk. A large open-plan warehouse with high racking may require beam detectors or aspirating smoke detection rather than conventional point detectors. The system should be regularly tested and serviced in accordance with BS 5839.
- Inspect and maintain fire doors. Fire doors are among the most important passive fire protection measures in any building, and among the most neglected. In a warehouse environment, they are subjected to constant use by forklift trucks and pedestrians and deteriorate quickly. Regular fire door inspection is not a luxury; it is a fundamental requirement.
- Implement a hot work permit system and enforce it. This should apply to contractors as well as directly employed staff. The post-work fire watch is non-negotiable.
- Manage combustible waste rigorously. Remove waste from the building daily. Keep external waste storage away from building walls and secure it against arson. Do not allow cardboard, packaging film, or pallets to accumulate in loading bays, escape routes, or near electrical equipment.
- Address lithium-ion battery risks specifically. Designate charging areas, implement impact damage reporting, and ensure the fire risk assessment has been reviewed to reflect any introduction of lithium-ion technology on site.
- Train all staff, including contractors, in fire safety procedures. Fire safety training should cover evacuation procedures, the location and use of fire-fighting equipment, how to report concerns, and — importantly — the specific fire risks of the facility. A generic fire safety briefing is not adequate for a high-hazard industrial environment.
- Review security arrangements with arson risk in mind. Perimeter security, lighting, CCTV coverage, and out-of-hours access controls should all be considered as part of the fire risk assessment, not only as general security measures.
- Ensure sprinkler systems, where installed, are properly maintained. A sprinkler system that has not been serviced or that has been isolated during building works may provide no benefit at the critical moment. Maintenance contracts should be in place and compliance verified.
- Maintain records and documentation. Under the Building Safety Act 2022 and the FSO, responsible persons are required to keep records of fire safety measures. This includes risk assessments, fire door inspection records, maintenance logs, and training records.
Under the Regulatory Reform (Fire Safety) Order 2005, the responsible person for any warehouse or industrial premises has a legal duty to carry out and implement a suitable and sufficient fire risk assessment, maintain the premises to a fire-safe standard, and ensure all employees receive appropriate fire safety instruction and training. Failure to comply can result in enforcement action, improvement notices, prohibition notices, and — in serious cases — prosecution.
The Role of the Fire Risk Assessment
It is worth saying plainly that a fire risk assessment is not a bureaucratic exercise. In the hands of a competent assessor, it is the mechanism through which all the risks described in this article are identified, evaluated, and addressed systematically. The three case studies above — arson at a paper products warehouse, automated system failure at a robotic fulfilment centre, and spontaneous combustion at a plastic recycling facility — represent very different risk profiles, and each would require a different assessment methodology and a different set of control measures.
Generic or template-based assessments, completed without adequate knowledge of the specific operations, building characteristics, and material hazards involved, will miss precisely the risks that matter most. The Ocado fire, for instance, required an understanding of the fire behaviour of lithium-ion battery systems and robotic warehouse infrastructure that had no obvious precedent at the time. The Monoworld fire required an assessor with knowledge of spontaneous combustion dynamics in plastic recyclate. The appropriate response to arson risk at a paper warehouse is different again.
Assessor competence is a live issue in the UK fire safety sector. BS 8674:2025, the new British Standard for fire risk assessors, and the BAFE SP205 scheme provide frameworks for verifying that an assessor has the knowledge and experience appropriate to the premises type. For a high-hazard or complex warehouse environment, those credentials matter.
Fletcher Risk Management provides fire risk assessments, fire door inspections, and fire safety training for warehouse and industrial premises across Chester, Cheshire, the Wirral, Merseyside, Greater Manchester, North Wales, and the wider North West. If you have concerns about the adequacy of your current fire safety arrangements, or if your risk assessment has not been reviewed since your operations or building changed, we would be happy to help.
Need a Warehouse Fire Risk Assessment?
Fletcher Risk Management provides competent, thorough fire risk assessments for warehouse and industrial premises across Chester, Cheshire, the Wirral, Merseyside, Greater Manchester, and North Wales. We also offer fire door inspections and fire safety training tailored to industrial environments.
If your current assessment is out of date, or if operations have changed since it was last reviewed, please get in touch.
Disclaimer: This article is intended as general guidance only and does not constitute formal fire safety advice. Every premises is different, and the fire risks applicable to your building will depend on its specific construction, use, occupancy, and operational activities. A competent fire risk assessment, carried out by a qualified assessor with appropriate experience, is the only reliable basis for managing fire risk in your premises. Fletcher Risk Management Limited accepts no liability for any loss or damage arising from reliance on the general information contained in this article.