Suspected cannabis farm incidents attended by fire and rescue services have risen 218% over the past decade, reaching a record 54 in 2024, as new data from Zurich UK reveals the insurer has investigated £9.4m in related landlord claims since 2022.
Freedom of information requests submitted by Zurich to 21 fire and rescue services show callouts remained near record levels in 2025, with 50 attendances recorded. Incidents rose 59% between 2019 and the 2024 peak, pointing to a significant intensification of the problem in recent years. Home Office analysis recorded 640 cannabis farm fires across the UK between 2019 and 2024, corroborating the trend.
South Wales Fire and Rescue Service attended the highest number of suspected or identified cannabis farms of any service in the study, responding to 90 properties over seven years and peaking at 25 incidents in 2020. Essex County Fire and Rescue Service ranked second with 56 attendances over a decade, and Hereford and Worcester Fire and Rescue Service recorded 55 over the same period.
Zurich's Claims Investigation Unit Major Loss team has handled 17 cannabis farm-related claims worth a combined £9.4m since January 2022. The insurer says the damage profile from these operations extends well beyond fire risk, with investigators finding commercial units extensively altered to support growing operations, electrical systems tampered with to meet cultivation demands, and significant structural changes made to conceal activity. The consequences for landlords include extensive reinstatement work, prolonged vacancy and substantial repair costs before buildings can be safely reoccupied.
"Many landlords still picture cannabis farms operating in remote industrial estates or hidden warehouses," said Scott Clayton, head of claims fraud for Zurich UK. "What we're increasingly seeing is organised criminal groups targeting empty shops, offices and retail premises, often hiding in plain sight on high streets across the UK.
"These operations can involve sophisticated attempts to present a legitimate business front, making it difficult for landlords to spot the warning signs until significant damage has already been done.
"Our specialist Claims Investigation Unit has dealt with cannabis farm claims worth £9.4 million since 2022 alone, highlighting the scale of the problem. Robust due diligence, regular inspections and a willingness to question unusual behaviour remain some of the most effective ways landlords can protect themselves from a growing and costly threat."
Stewart Powell, regional major loss lead for Zurich UK, said the full scale of the damage typically only becomes clear once a farm has been uncovered.
"While the fire risk associated with these operations is well known, fire is often only one part of a much larger problem," Powell said. "We've seen claims involving dangerous electrical alterations, extensive water damage from irrigation systems, widespread damp and mould, and significant structural changes made to conceal growing operations.
"By the time a property is recovered, landlords can be left facing months of disruption, substantial reinstatement work and repair bills running into hundreds of thousands of pounds before a building can be safely occupied again."
Zurich has set out a series of due diligence questions landlords should consider before letting a commercial property, and a checklist of warning signs that a property may already be in use for cultivation.
Before letting: questions to ask
- Is the prospective tenant willing to pay the asking rent without negotiation despite challenging market conditions?
- Is the tenant prepared to enter a high-value, long-term lease without involving solicitors?
- Does the proposed business activity appear commercially unrealistic?
- Are identification documents or proof of address difficult to verify?
- Does the tenant live a considerable distance from the property?
- Does the tenant insist on paying deposits or rent in cash?
- Does the tenant ask for inspection clauses to be removed from the lease?
- Does the tenant have any history of operating commercial premises?
- Is the tenant trading through a newly incorporated company with little or no financial history?
Signs a property may be in use for cannabis cultivation
- The business never appears to open or trade.
- The tenant requests permission to sublet shortly after taking possession.
- The tenant becomes difficult to contact or repeatedly avoids inspections.
- Rent payments become difficult to collect.
- Local authorities make contact regarding unpaid business rates.
- Utility providers contact the landlord regarding unpaid bills.
- Internal walls or partitions are installed without a clear business reason.
- Security shutters or screening are fitted to conceal activity.
- External ducting or ventilation systems appear without permission.
- Blacked-out windows, excessive condensation or strong, unusual odours.
- Unexplained alterations to electrical systems or unusually high humidity.
