Vacant Property Monitoring: Doors, Frost and Leaks Between the Weekly Inspections

TL;DR: A vacant property is visited once a week at best, and most of what damages it happens in the days between. Insurer guidance such as Aviva’s expects internal and external inspections at least every seven days, because burst pipes and water ingress in empty buildings can go undiscovered. Door, temperature, humidity and leak sensors on a 4G gateway fill those days with a dated record and alerts. They add to inspections and a certified intruder alarm; they do not replace either.

Last updated: 14 September 2026

Key takeaways

• A vacant property is more vulnerable to damage than an occupied one, even for a short vacancy, according to Aviva’s loss prevention guidance on unoccupied premises.
• The same guidance says empty premises should be inspected internally and externally at least every seven days, with a log kept.
• It warns that burst pipes from frozen water and water ingress can go undiscovered in empty buildings for some time.
• Door, temperature, humidity and leak sensors turn the six days between inspections into a dated record, with alerts when something changes.
• Sensors are not an intruder alarm and do not replace inspections; they tell you which visit cannot wait a week.

Why is a vacant property at risk?

A vacant property is at risk because nobody is there to notice the first sign of trouble. Aviva’s loss prevention standard for unoccupied premises says unoccupied properties are more vulnerable to damage than similar occupied premises, even if the vacancy is short, and names fire, malicious damage, theft and water damage as the main hazards.

Water is the quiet one. The guidance explains that burst pipes, water ingress and flooding in empty buildings can go undiscovered for some time, and that pipes can burst when water freezes if mains supplies stay on through the winter. A leak found on a weekly visit has had up to seven days to soak through floors and ceilings.

Vacancies also last longer than owners plan. Business rates give only a short break: GOV.UK’s guidance on empty property relief says empty property is exempt for 3 months, with industrial premises such as warehouses exempt for a further 3 months, after which most businesses must pay full business rates. An empty building quickly becomes an expensive one to leave unwatched.

What do insurers expect for an empty building?

Insurers set their own conditions for an unoccupied vacant property, so the policy wording decides. Aviva’s loss prevention standard gives a clear picture of what good management looks like, and most of it is about inspections, security and water.

None of that is replaced by a sensor. What vacant property monitoring adds is the part inspections cannot cover: what happened between Tuesday’s visit and next Tuesday’s.

What should you monitor in a vacant property?

Monitor the four things that go wrong unseen in a vacant property: doors and windows opened, temperatures falling towards freezing, humidity rising into damp, and water on the floor. Each has a simple battery sensor that needs no wiring.

1. External doors and vulnerable windows. An opening outside a scheduled visit is the earliest sign of intrusion or squatting.
2. Temperature in the coldest room. A falling trend in a cold snap is the warning before pipes freeze, whether or not the building has been drained.
3. Humidity. Weeks of high humidity in a closed building lead to damp, mould and damaged finishes.
4. Leaks at the stopcock and boiler. Where water remains live, a leak sensor catches the first water on the floor.

In a cold, damp empty building, the sensors themselves need to cope. IP67 door sensors such as the EM300-MCS are rated from -30°C to 70°C and log temperature and humidity at every door, which suits a vacant property far better than indoor-only models.

Why use a 4G gateway?

Use a 4G gateway because an empty building rarely has broadband, and even when it does, nobody is there to fix it when it drops. A LoRaWAN gateway with 4G built in sends every alert over the mobile network, independent of any line in the building.

The gateway does need mains power. If the building’s supply is cut, alerts stop until power returns, though battery sensors keep recording and resend what they logged. Check with whoever manages the supply that the circuit feeding the gateway will stay live during the vacancy.

What are the limits of sensors in an empty building?

Sensors watch a vacant property; they do not protect it. Four limits matter.

• They are not an intruder alarm. A door sensor records an opening; it has no siren, no alarm receiving centre and no certification to BS EN 50131. Where a policy requires a certified alarm, it still does.
• They do not replace inspections. Insurer conditions such as weekly visits still apply. Share the sensor record with your insurer rather than assuming it changes the terms.
• They need the gateway powered. Plan the supply, or the alerts stop with it.
• A leak sensor sees only its own spot. It detects water where it sits, so place it where water would collect first.

What does a vacant property kit include?

A vacant property kit needs a 4G gateway, IP67 door sensors, temperature and humidity sensors and a leak sensor. Our vacant property monitoring kit combines a UG63 gateway with 4G, three EM300-MCS door sensors, two EM300-TH temperature and humidity sensors and a WS303 leak sensor, with live prices and one click to the basket.

The same parts move to the next empty building when this one is let, because nothing is wired in. For more on door sensors, see our guide to wireless door sensors, and for damp specifically, our damp and mould monitoring guide.

Frequently asked questions

How often should an empty building be inspected?

Aviva’s loss prevention guidance for unoccupied premises says inspections should be carried out internally and externally at least every seven days, with a log maintained. Always follow your own policy’s conditions.

Do sensors replace an intruder alarm in a vacant property?

No. Door sensors record openings but are not a certified intruder alarm with remote signalling to an alarm receiving centre. Where a policy requires an alarm, keep it.

How do you stop pipes freezing in an empty building?

Aviva’s guidance describes isolating valves and draining systems where water is not needed, and keeping heating on frost-stat control at a minimum of 4°C where sprinklers remain charged. Temperature sensors warn when a building is getting close to freezing.

Does a vacant property need broadband for monitoring?

No. A LoRaWAN gateway with 4G sends alerts over the mobile network. It needs mains power and a SIM with a data plan.

How long do business rates stay free on an empty property?

GOV.UK says empty property relief removes business rates for 3 months, with industrial premises such as warehouses exempt for a further 3 months, after which most businesses pay full rates.

Watch the six days between visits

A vacant property does most of its damage between inspections. Keep the weekly visits and the certified alarm, and let door, temperature, humidity and leak sensors tell you when a visit cannot wait.

See the vacant property monitoring kit with live prices, or send us the building’s floor plan and an engineer will size the kit within one working day.

By GP, Indiott.