Figures from Zurich UK indicate a significant surge in cannabis farms in rented properties, with fire service callouts increasing from 17 in 2015 to 54 in 2024, prompting calls for landlords to strengthen tenant screening.
Fire service callouts surge
In 2025, fire departments responded to 50 incidents linked to cannabis farms, continuing a trend of raised activity. Data from 21 fire services reveals a 59% surge in such cases between 2019 and the peak in 2024. The South Wales Fire and Rescue Service handled the most calls, responding to 90 suspected or confirmed cannabis operations over seven years.
Essex County Fire and Rescue Service dealt with 56 cases over the past ten years, while Hereford and Worcester Fire and Rescue Service recorded 55. A separate Home Office report found 640 cannabis farm fires occurred nationwide between 2019 and 2024.
Extensive property damage
Criminal groups make dangerous alterations to properties used for cannabis cultivation. They tamper with electrical systems to meet high energy demands, while irrigation equipment causes water damage, damp, and mould. Unauthorised internal alterations and ventilation systems create further problems, leaving landlords with months of reinstatement work.
Zurich’s Claims Investigation Unit has investigated 17 cannabis farm-related claims since January 2022, worth a total of £9.4 million. Scott Clayton, head of claims fraud at Zurich UK, said: “Many landlords still picture cannabis farms operating in remote industrial estates or hidden warehouses,” he explained.
Criminal groups target high streets
Criminal networks are increasingly exploiting vacant commercial spaces—such as shops and offices—often blending in with legitimate businesses on main streets. They may disguise their operations under the guise of normal activity, leaving property owners unaware of the damage until it’s already severe.
Property owners could end up paying repair costs amounting to hundreds of thousands. Stewart Powell, Zurich UK’s regional major loss specialist, explained: ‘Landlords often don’t realise the full scope of the damage until a cannabis farm is discovered and its destruction is exposed.’
Warning signs for property owners
While fire hazards are a known risk, they’re just one aspect of the broader issues these operations create. Claims have included unsafe electrical modifications, severe water damage from irrigation, pervasive damp and mould, and major structural changes to hide growing setups.
Red flags may appear even before a lease begins. Potential tenants might agree to the listed rent without discussion or pursue long-term, high-value leases without legal representation. Demands for cash payments for deposits or rent should also raise suspicion.
Owners should carefully examine identification that’s hard to verify and be wary of newly formed companies with minimal financial records. Once a tenancy starts, signs of trouble include spaces that never seem operational and tenants who consistently dodge inspections.
They should also watch for blackout windows, excessive condensation, and unusual odours, all of which can indicate hidden activity. Unexplained alterations to electrical systems, internal partitions, or external ventilation merit further investigation, as do unusually high humidity levels and approaches from councils or utility companies about unpaid bills.
