The heating behaviour landlords always notice too late

In let properties, the most expensive arguments rarely start with mould or broken boilers. They start with predictable heating behaviour that looked “fine” on paper, right up until the first proper cold snap and the meter readings land.

A tenant isn’t trying to be difficult when they heat a home in a certain way. They’re trying to feel warm, keep the place dry, and control bills. The problem is that the pattern they choose can quietly push a property past its comfort zone - and landlords often only spot it when the damage has already been negotiated into the relationship.

The slow, tidy pattern that creates the biggest mess

There’s a type of heating that looks sensible from the outside: short bursts, usually morning and evening, with the thermostat cranked up “just to get it going”. Windows shut. Doors closed. Then everything off again to save money.

It feels efficient because the heating is “only on when needed”. But in many homes - especially older flats, converted terraces, and anything with marginal insulation - that stop‑start rhythm can keep surfaces cold for long stretches. Cold walls plus everyday moisture equals a dew point you can’t argue with.

The giveaway isn’t always visible mould at first. It’s a bedroom that smells a bit “flat”, a corner that never quite dries, a window that runs with water even when it’s barely freezing outside. By the time someone wipes it daily, the property is already on the back foot.

Why landlords notice it too late

Because the early signs sit in the gaps between visits. A quarterly inspection catches the room on a “good day”: the heating has been on for an hour, the air feels warm, the tenant has had a quick tidy. The wall behind the wardrobe doesn’t get moved, so nobody sees the cold patch doing its quiet work.

And because the numbers look plausible. Usage can be low, which reassures everyone, yet low usage in a leaky or hard-to-heat home often means the fabric never warms through. The building stays cold, moisture keeps cycling, and the damage expresses itself slowly.

The property doesn’t respond to intent. It responds to temperature, humidity, and time.

The physics tenants aren’t told - and landlords forget to explain

Moisture is made in normal life: showers, cooking, drying clothes, breathing. In a well-managed home, that moisture is removed (ventilation) and the structure is kept above the point where water condenses (steady heat).

Predictable heating behaviour becomes a problem when it creates these conditions:

• Big temperature swings: warm air holds moisture, then cools against cold walls and drops it as liquid.
• Closed-in air: extractor fans unused, trickle vents shut, windows never cracked because “it wastes heat”.
• Cold furniture zones: wardrobes on outside walls, sofas tight to corners, beds pushed against cold plaster.

If you’ve ever seen mould appear in a perfect rectangle, that’s not “damp coming through”. That’s a wardrobe acting like a lid on a cold surface, with stop-start heating feeding it warm, wet air twice a day.

What sensible landlords do instead (and it’s not “tell them off”)

They make the right behaviour easy to follow, and they explain the why without sounding like a lecture. The trick is to give tenants a simple routine that protects the fabric of the building and respects cost concerns.

A workable approach for many let properties looks like this:

• Aim for steadier low heat, not spikes. A lower thermostat for longer can reduce condensation risk compared to blasting then shutting off.
• Vent moisture at the source. Use kitchen and bathroom extractors; keep doors shut while cooking/showering; crack a window for ten minutes rather than leaving it ajar all day.
• Keep air moving in cold corners. Leave a small gap behind furniture on outside walls; don’t overfill wardrobes; open internal doors briefly to equalise temperatures.
• Dry clothes with a plan. If there’s no tumble dryer, use a rack in the warmest ventilated room, extractor on, door closed, and don’t do three loads back-to-back in a tiny box room.

None of this requires a perfect building. It requires consistency - the kind that stops surfaces dipping into the danger zone every night.

The three places to look before you blame the boiler

If you want to spot the pattern early, don’t start with the thermostat. Start with the places that tell the truth.

1. Windows in the morning. A little condensation happens; streaming panes most days suggests moisture isn’t being shifted.
2. Behind big furniture on external walls. Especially north-facing bedrooms, corners, and chimney breasts.
3. Bathroom and kitchen extraction. Fans disconnected, noisy, or weak are an invitation to damp even in a well-heated home.

You’re not hunting for fault. You’re checking whether the home can actually cope with normal living under the tenant’s routine.

A short message that prevents long disputes

Landlords often send paragraphs about “ventilation” that nobody reads. Tenants often hear “you’re doing it wrong” when you mean “this building needs a different rhythm”.

A better message is practical, specific, and small enough to follow:

• Keep the home at a steady background temperature in cold spells.
• Use the extractor every time you shower or cook, and for 15–20 minutes after.
• Wipe window condensation and report it if it’s daily.
• Don’t push wardrobes tight to cold outside walls.

That’s it. If the property still struggles, then you have clean evidence it’s a building issue - not a behaviour issue - and you can talk insulation, ventilation upgrades, or heating controls without the conversation turning personal.

Point clé	Détail	Intérêt pour le lecteur
Stop-start heat looks “efficient”	Cold surfaces stay cold; moisture condenses when heat drops	Fewer mould call-outs and complaints
Early signs hide between inspections	Condensation, smell, cold corners behind furniture	Fix issues before deposits and disputes
Small routines beat big lectures	Steady background heat + targeted ventilation	Protects fabric while respecting bills

FAQ:

• What’s the most common predictable heating behaviour that causes mould? Short, high bursts of heat morning/evening with long cold gaps, paired with low ventilation and indoor clothes drying.
• Should tenants leave the heating on all day? Not necessarily. The goal is steady background warmth during cold spells, avoiding big temperature swings that chill walls and trigger condensation.
• Is condensation always the tenant’s fault? No. Weak extraction, poor insulation, cold bridges, and under-sized heating can make “normal living” create daily condensation.
• What’s the quickest check at an inspection? Look for regular morning window condensation, damp smells in bedrooms, and mould behind furniture on external walls.
• What upgrade helps most in many let properties? Reliable extraction (quiet, effective bathroom/kitchen fans) and simple heating controls tenants can actually use consistently.