The best damp and mould monitoring for landlords in 2026

A damp and mould sensor measures temperature, relative humidity and, on better devices, volatile organic compounds and carbon dioxide, then converts those readings into a mould risk score. It tells a landlord that conditions in a property favour mould growth weeks before anything becomes visible. The technology was built for social housing, where statutory response deadlines already bite, and it is now reaching private landlords with larger portfolios. Whether it is worth buying depends almost entirely on how many properties you hold and how far apart they are.

Does Awaab's Law apply to private landlords?

No. As of September 2026, Awaab's Law binds registered providers of social housing only. It has been in force since 27 October 2025 under the Hazards in Social Housing (Prescribed Requirements) (England) Regulations 2025, which set fixed timescales for social landlords to investigate and act on damp, mould and emergency hazards.

The Renters' Rights Act 2025 carries the power to extend those duties to private landlords, alongside the wider property standards reforms. That extension sits in Phase 3 of the Act's implementation roadmap, it requires separate regulations that have not been laid, and the government has said it will consult before setting timescales. No commencement date exists. Most legal commentary points to 2027 at the earliest, and the detail of what is and is not in force is worth reading in full.

This matters when buying, because most vendors in this category sell on Awaab's Law compliance. For a private landlord that is a forward-looking argument, not a current legal requirement, and it should be weighed as such.

What private landlords already owe

Existing law already requires you to deal with damp and mould, which is the part the Awaab's Law debate obscures. Section 11 of the Landlord and Tenant Act 1985 obliges you to keep the structure and exterior in repair, and damp entering through a defective roof, wall or window falls squarely inside it. The Homes (Fitness for Human Habitation) Act 2018 lets a tenant take a landlord to court directly where a property is unfit, and serious damp and mould makes a home unfit. Councils assess damp and mould as a category 1 hazard under the rating system and can serve improvement notices today, without waiting for any extension.

The Decent Homes Standard reaches the private rented sector in 2035 and sets the baseline condition a home must meet. Awaab's Law, when it arrives, will govern how fast you respond once a hazard is reported. The two work in sequence rather than overlapping.

Who monitoring actually suits

Environmental monitoring earns its cost where you cannot see a property often enough to notice a problem forming. That is a portfolio question, not a compliance one.

Ten or more units, or geographically dispersed stock. Platform monitoring is straightforward to justify. Per-property hardware cost is low against a single disrepair claim, and the dashboard replaces inspection visits you were never realistically going to make.

Three to nine units. Marginal. Consumer-grade sensors at a fraction of platform cost will tell you most of what a platform would, without the portfolio dashboard. The decision turns on whether you want alerts or reports.

One or two units. Hard to justify a platform. A single consumer monitor in the highest-risk room, usually the bathroom or a north-facing bedroom, delivers most of the value.

Shared houses concentrate the risk, because occupancy density drives moisture load. An HMO with five occupants generates far more moisture than a couple in the same building, and it is the stock type where monitoring pays back fastest regardless of portfolio size.

Switchee

Switchee is the most capable option for landlords managing at portfolio scale, and the least accessible for anyone else. The device replaces the property thermostat and measures temperature, humidity, motion and carbon dioxide, using the combination to model mould risk and flag properties before conditions become visible. Because it sits in the heating loop, it reads something most sensors cannot: whether a tenant is heating the home at all, which is frequently the root cause rather than ventilation.

The platform was built for housing associations and local authorities, and the commercial model reflects that. It is sold as a managed deployment with a portfolio dashboard, not as a product you buy one of. For a landlord with a substantial portfolio or an agency managing stock on behalf of others, that is the right shape. For a landlord with two flats, it is not a realistic purchase.

The tenant-facing side is worth noting. The device screen can carry messages to occupants, which turns a mould risk alert into a prompt at the property rather than a phone call.

Aico HomeLINK

Aico HomeLINK extends an alarm estate into environmental monitoring, which makes it the natural choice if you already run Aico fire and carbon monoxide alarms. The environmental sensors report temperature, humidity and air quality through a gateway, and the platform presents property-level risk alongside alarm status.

The advantage is consolidation. Compliance data and environmental data arrive in one place, and the hardware comes from a manufacturer landlords already know from the alarm side. The constraint is the same as Switchee: this is a professional installation sold into managed portfolios, priced and supported accordingly. Retrofitting it to a handful of properties without an existing Aico estate is poor value.

Airthings

Airthings is the practical choice for landlords with small portfolios, because it is the only option here you can simply buy. The monitors measure humidity, temperature, volatile organic compounds and, on several models, radon, and they report to a phone app without installation or a service contract.

The trade-off is that Airthings is a consumer product doing a professional job. There is no portfolio dashboard designed around managing many properties, no tenant messaging, and no compliance reporting. You get the readings and act on them yourself. For one to five properties that is usually enough, and it costs a fraction of a platform deployment.

Radon detection is a genuine extra rather than a bullet point. Radon is a category 1 hazard in its own right in parts of the country, and few landlords test for it.

FluxSense

FluxSense sits in the specialist end of the market, aimed at diagnosis rather than continuous portfolio monitoring. Where the platforms above are built to watch many properties over time, this class of tool is built to work out what is happening in one property that already has a problem.

That makes it a complement rather than an alternative. A landlord dealing with a recurring damp issue that survives repeated remediation needs diagnosis, not another humidity chart. Confirm current specification and commercial terms directly, as this part of the market moves quickly.

Sensors and test kits do different jobs

A mould test kit identifies whether mould is present and sometimes what species. A sensor predicts whether conditions favour mould before it appears. They answer different questions, and the confusion between them is why many landlords buy the wrong one.

Buy a test kit when a tenant has reported a problem and you need to establish what is there. Buy a sensor when you want to stop that report happening. For most landlords the sensor is the better purchase, because the expensive part of a damp problem is never the test, it is the remediation and the claim that follows.

Can you monitor a tenanted property lawfully?

Yes, provided you monitor the environment rather than the occupants and you tell the tenant. Environmental sensors record temperature, humidity and air quality, which is property data, but readings such as motion or carbon dioxide can indicate occupancy patterns, and that makes them personal data under UK GDPR.

Three things keep this straightforward. Tell the tenant what the device measures and why, in writing, ideally at the point the tenancy starts. Collect only what you need for the stated purpose. Never install anything with a camera or microphone. Handled that way, monitoring strengthens the relationship, because the tenant can see you are watching the building rather than them.

Working with self-managing landlords across the UK, the objection we hear most is not privacy but suspicion that a sensor is there to blame the tenant for condensation. Framing it as the landlord taking responsibility for the building, and saying so plainly, defuses that before it starts.

What to do when a sensor flags a property

An alert is only worth the cost of the hardware if it produces a recorded response. The pattern that works is a short, consistent sequence: acknowledge the alert, contact the tenant to establish what has changed, inspect if readings persist beyond a fortnight, then act on the cause rather than the symptom.

Sensors tell you conditions are deteriorating; they do not fix the underlying cause, which is usually ventilation, heating cost or a building fault. A humidity spike in a property where the tenant has stopped heating the back bedroom is an affordability problem wearing a moisture costume, and a dehumidifier will not solve it.

Pair the data with a physical inspection routine rather than treating it as a replacement for one. The sensor tells you which property to visit. It does not tell you what you will find when you get there.

Whatever you decide, log the report, the response and the outcome against the property, so the sequence is reconstructable months later.

Building an evidence trail

The evidence trail, not the sensor, is what protects you. A documented environmental record is the strongest evidence a landlord can hold if a housing disrepair claim follows, because it establishes both what the conditions were and what you did about them.

Across the portfolios managed on August, the landlords who come through disrepair disputes well are rarely the ones with the best properties. They are the ones who can produce a dated sequence showing a report, a response and a resolution. Continuous monitoring data makes that sequence easier to assemble, but only if the response side is recorded somewhere durable.

That is worth settling before the hardware arrives. Sensor data lives in the vendor's dashboard; your correspondence, invoices and inspection notes usually do not, and a claim needs both. Keeping compliance records in one place alongside the property is what turns readings into a defence.

The verdict

For portfolios above roughly ten units, or for agencies managing stock on behalf of landlords, Switchee is the strongest option, because the heating-loop data explains causes that humidity readings alone cannot. If you already run an Aico alarm estate, Aico HomeLINK wins on consolidation before it wins on capability.

For everyone else, Airthings is the sensible purchase. It is available, it is cheap relative to a platform, and for a small portfolio the difference between consumer and professional hardware is far smaller than the difference between monitoring and not monitoring.

Buy the monitoring for the operational benefit, which is real today. Do not buy it because Awaab's Law requires it, because as of September 2026 it does not.

Frequently asked questions

What humidity level causes mould? 

Sustained relative humidity above 70% at surface level allows most mould species to grow, though the surface temperature matters as much as the air reading. A cold external wall can hold surface humidity far above the room average. This is why sensors that read temperature and humidity together produce more useful risk scores than humidity alone.

Do I have to tell my tenant I have installed a sensor? 

Yes. Where a device records data that could indicate occupancy, it processes personal data under UK GDPR, and the tenant must be told what is collected and why. Put it in writing at the start of the tenancy.

Will a sensor stop a disrepair claim? 

Not by itself. It strengthens your position by evidencing conditions and your response, which is usually the contested part of a claim. A sensor with no recorded follow-up can weaken your position instead, by showing you knew.

Is monitoring worth it for one property? 

A consumer monitor in the highest-risk room is, at roughly the cost of a single call-out. A platform deployment is not. August is free to start for free if you want the inspection and compliance side in order first.