Cannabis farms hiding in plain sight leave landlords facing millions in damage

New data released today by Zurich UK reveals a sharp rise in the number of suspected or identified cannabis farms attended by fire and rescue services, with incidents increasing by 218% from 17 in 2015 to a record 54 in 2024¹. In the past few years, Zurich has investigated £9.4 million in 17 cannabis farm-related claims².

Freedom of information data obtained by Zurich from 21 fire and rescue services shows incidents remained near record levels in 2025, with 50 attendances recorded. The problem has intensified significantly in recent years, with incidents increasing by 59% between 2019 and the 2024 peak.

South Wales Fire and Rescue Service recorded the highest number of attendances, responding to 90 suspected or identified cannabis farms over the past seven years, with a peak of 25 incidents in 2020. Essex County Fire and Rescue Service ranked second, attending 56 cannabis farms over the past decade, while Hereford and Worcester Fire and Rescue Service recorded 55 attendances over the same period.

Home Office analysis further corroborates Zurich’s findings, identifying 640 cannabis farm fires across the UK between 2019 and 2024³.

What this means for insurers

Since January 2022, Zurich's Claims Investigation Unit Major Loss team has investigated 17 cannabis farm-related claims worth a combined £9.4 million, highlighting the significant damage these operations can cause. The warning comes amid evidence that cannabis production is increasingly moving into rented properties and vacant commercial premises.

Investigators have encountered commercial units extensively altered to support growing operations, with electrical systems often tampered with to meet the significant energy demands of cannabis cultivation. These modifications can pose serious safety risks, leaving landlords facing extensive reinstatement work, lengthy periods of vacancy and substantial repair costs before buildings can be safely reoccupied.

Scott Clayton, Head of Claims Fraud for Zurich UK, said:

"Many landlords still picture cannabis farms operating in remote industrial estates or hidden warehouses. 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:

"For many landlords the full impact only becomes apparent once a cannabis farm has been uncovered and the extent of the damage becomes clear.

"While the fire risk associated with these operations is well known, fire is often only one part of a much larger problem. 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."

Before letting a commercial property: questions every landlord should ask

• Is a prospective tenant willing to pay the asking rent without negotiation despite challenging market conditions?
• Is a tenant prepared to enter into 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 being used 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
• Strong, unusual odours
• Unexplained alterations to electrical systems
• Unusually high levels of humidity within the property

Notes to editors

• ¹ Freedom of Information data obtained from 21 fire and rescue services across the UK who recorded attending suspected or identified cannabis farms between 2015 and 2025. 2015: 17 incidents, 2016: 9 incidents, 2017: 14 incidents, 2018: 15 incidents, 2019: 34 incidents, 2020: 49 incidents, 2021: 41 incidents, 2022: 44 incidents, 2023: 39 incidents, 2024: 54 incidents (record high), 2025: 50 incidents
• ² Cannabis farm fires - GOV.UK: Home Office analysis identified 640 cannabis farm fires between 2019 and 2024
• ³ Since January 2022, Zurich's Claims Investigation Unit (CIU) Major Loss team has investigated 17 cannabis farm-related claims with a combined value of £9.4 million