Carrier reports average £550,000 per claim
Walk down most UK high streets and you'll pass at least one shuttered unit that's been empty for months. A nail bar that never reopened. A "to let" sign that's gone slightly grey in the rain. According to Zurich UK, some of those units aren't empty at all, they've been quietly turned into cannabis farms, and the damage bill is landing on landlords' insurers.
New analysis from the insurer, covering 17 cannabis farm-related claims it has handled since January 2022, puts the total cost at £9.4 million. That's an average of more than £550,000 per claim and it doesn't include the months of lost rent while a gutted building sits empty waiting for six-figure repairs before anyone can move back in.
Fire crews are being called out more than ever
The claims data lines up with a longer-running trend in emergency service call-outs. Freedom of Information requests sent to 21 fire and rescue services show suspected cannabis farm incidents rose 59% between 2019 and a peak in 2024. Zurich's own figures, drawn from the same FOI exercise, show call-outs climbing 218% between 2015 and 2024, from 17 incidents to a record 54, with 50 recorded last year alone.
The Home Office's own published statistics on cannabis farm fires tell a similar story nationally, recording 640 such incidents across England between 2019 and 2024. South Wales fire crews reported the highest regional caseload, attending 90 suspected farms over seven years with a peak of 25 in a single year. Essex and the Hereford and Worcester service weren't far behind, each logging in the mid-fifties over the past decade.
Worth noting: that trend isn't uniform everywhere. London Fire Brigade's own published figures actually show a decline in cannabis-related fires over roughly the same window, from 19 incidents in 2019 down to 10 in 2024. That's not necessarily a contradiction as Zurich's figures cover a longer run back to 2015 and look at the national picture, and there's a reasonable case that criminal operators have simply been pushed toward cheaper premises outside the capital. But it's a reminder that national averages can mask quite different local pictures, which matters if you're advising clients on regional risk.
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It's not just industrial estates anymore
For years, the working assumption among landlords and brokers was that cannabis farms belonged in remote warehouses or industrial units, out of sight and out of mind. Zurich says that picture is out of date. Its claims fraud team is increasingly finding operations set up in empty shops, offices and other retail premises on ordinary high streets, spaces chosen precisely because a shuttered unit next to a coffee shop attracts far less suspicion than a lock-up on an industrial estate.
That shift matters for brokers advising commercial property clients, not just residential landlords. A vacant retail unit that would once have been treated as a low-risk, low-activity asset can now carry a meaningful fraud and claims exposure, one that standard vacancy clauses and inspection regimes weren't necessarily built around.
The damage itself tends to follow a familiar pattern once investigators get inside: electrical systems tampered with to cope with the power draw of grow lights, water systems adapted for irrigation that instead flood the building, and structural alterations including stripped-out partitions, holes cut for ventilation ducting which are made to disguise what's really going on.
By the time any of this is discovered, landlords are typically looking at extensive damp and mould on top of the structural work, and months of void period before the building is safe to relet.
Zurich's £9.4 million across 17 claims works out at an average of roughly £550,000 per case, well above the figures other insurers have reported for cannabis farm damage in recent years. Aviva put its average claim at £9,471 back in 2020, and Total Landlord Insurance has reported an average of £7,488 across 38 claims between 2019 and 2024.
The gap is a useful signal in itself: it suggests Zurich's book is weighted toward larger, commercial-scale operations rather than the smaller residential grow rooms that make up the bulk of other insurers' claims data.
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The tenants who look too good to be true
Zurich's investigators have compiled a set of red flags they say tend to show up before a lease is even signed: prospective tenants who accept the asking rent without any negotiation, resistance to using a solicitor on a high-value lease, requests to drop routine inspection clauses, and companies with almost no financial track record incorporated shortly before applying to rent.
Once a tenancy is underway, the warning signs tend to be more physical, like blacked-out windows, ducting fitted to the outside of a building without permission, a business that never seems to open or trade, and a strong, unusual smell that visitors to neighbouring units can't quite place. Individually, none of these prove anything. Together, insurers say, they're the pattern that shows up again and again once a farm has already been found.
What makes these operations hard to catch early, according to Zurich, is how deliberately they're set up to look legitimate including props like a working till, some stock on shelves, enough activity to survive a passing glance from a letting agent or a landlord doing a drive-by check.
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What this means for brokers
Cannabis farms sit at an awkward intersection of fraud, property risk and organised crime, and that combination creates real complications at claims stage. Landlord policies don't automatically treat this kind of damage the same way as an accidental escape of water or a kitchen fire as cover can depend heavily on whether reasonable tenant vetting and inspection routines were in place, which is exactly the kind of detail that gets scrutinised once an insurer starts asking questions.
For brokers, the practical takeaway is less about the eye-catching headline figure and more about the advice gap it points to. Commercial and residential landlord clients alike benefit from being walked through referencing standards, inspection frequency and what their policy actually expects of them if a property stands empty for any length of time.
Given how routinely the Association of British Insurers reports rising detected fraud across property lines each year, cannabis cultivation looks less like an isolated curiosity and more like one strand of a much bigger claims integrity problem the market is trying to get ahead of.
