Ventilation in a Winter Let, Trickle Vents, Extractors and Drying Washing

The mechanism, not the complaint

A separate piece on this site back in September covered what to do once condensation and prevention advice is already needed, closing windows less, wiping surfaces, the standard response once the problem has already shown up on a cold windowsill. This piece goes a step earlier, to the actual mechanism producing that moisture in the first place, because understanding where the water is actually coming from changes how seriously a landlord or tenant treats the ventilation that is supposed to be dealing with it.

Every tenanted property is, in a very literal sense, producing water constantly, just by being lived in. The question winter forces is whether that water is leaving the property as fast as it is being produced, or whether it is accumulating somewhere it should not.

What actually produces the moisture, and roughly how much

An ordinary household produces a genuinely large volume of water vapour every single day through nothing more than normal living. Breathing and general body moisture from the people living in a property accounts for a few litres a day on its own. Cooking, particularly boiling and steaming, adds a similar amount again. A single bath or shower releases roughly a litre and a half of water vapour into a bathroom’s air. Drying a single load of washing indoors on a rack, something that happens far more often in winter once outdoor drying stops being realistic, adds somewhere in the region of four to five litres on its own. Added together, a fairly ordinary household routine across breathing, cooking, washing and indoor drying can produce somewhere close to ten to fifteen litres of water vapour into a property’s internal air over a single day.

In summer, with windows open for a large part of the day, most of that moisture leaves a property as fast as it is produced, carried out on normal air movement without anyone thinking about it. In winter, with windows shut against the cold for most of the day and night, that same ten to fifteen litres has nowhere obvious to go, and it does not simply disappear, it settles somewhere, most visibly on the coldest surface in a room, which is usually a window, a north facing wall, or a corner with poor air circulation behind furniture.

Why trickle vents matter more than people realise

Trickle vents, the small slotted openings usually built into the top of a window frame, exist specifically to let a controlled, low level of air exchange happen even with the main window closed, precisely so a property is not relying entirely on someone remembering to open a full window through the coldest months. A high proportion of the trickle vents we find closed or painted shut on a winter property visit were not deliberately sealed by a tenant trying to keep heat in, they were simply closed at some point, often by a previous occupant, and never reopened, quietly removing the one piece of ventilation a room was specifically designed to keep running constantly in the background.

Checking every trickle vent in a property is open and free to move, not painted or filled shut, is one of the single highest value, lowest cost checks available on a rented property going into winter, and it takes minutes per room to confirm properly.

Extractor fans are supposed to be doing the heaviest lifting

Kitchen and bathroom extractor fans exist to remove moisture at the exact point it is being produced in the largest concentration, a boiling pan, a running shower, before it has the chance to spread through the rest of a property and settle elsewhere. An extractor fan that is not running long enough, that switches off the moment a light switch does rather than continuing to run for a set period afterward, or one that is simply not powerful enough for the room it serves, is not removing anywhere near the volume of moisture a bathroom or kitchen actually produces during and immediately after use.

A fan clogged with dust and grease from months of use loses a meaningful amount of its extraction capacity without ever visibly stopping working altogether, which is why a functioning fan is not automatically an effective one, and why cleaning extractor covers and filters is worth treating as a genuine winter maintenance task rather than an occasional afterthought whenever someone happens to notice it looks dirty.

Drying washing indoors is the single biggest controllable factor

Of everything covered above, indoor clothes drying is the factor a tenant has the most direct daily control over, and it is also the single largest controllable contributor to a property’s winter moisture load. A rack of washing drying in a closed bedroom, with the door shut and no ventilation running, releases several litres of water vapour directly into exactly the room least equipped to deal with it, since a bedroom typically has weaker ventilation than a kitchen or bathroom built with an extractor specifically for this kind of moisture load.

Where indoor drying cannot be avoided through winter, doing it in a room with a window cracked or a trickle vent open, with the door closed to stop moisture spreading through the rest of the property, and ideally with a dehumidifier running in that same room, keeps the same washing load from becoming a whole-property problem rather than a contained, manageable one.

Older Manchester housing has less natural ventilation to begin with

A lot of Manchester’s private rented stock, Victorian and Edwardian terraces in particular, was built with a level of natural draught and air leakage through original sash windows, chimneys and less airtight construction generally that modern building standards would never allow, but which did at least move air through a property constantly without anyone thinking about it. Once those properties are upgraded with modern double glazing and draught proofing, both genuinely worthwhile improvements for heating cost and comfort, the old, uncontrolled ventilation those draughts provided disappears with them, and trickle vents and extractor fans become the only routes left for exactly the moisture load described above to actually leave the building.

This is why an older Manchester property recently upgraded with new windows sometimes develops a worse condensation problem than it had before the improvement, not because the upgrade was done badly, but because it removed the accidental ventilation the property had relied on for a century without replacing it with anything deliberate. Checking that trickle vents were actually included and left open when new windows go in is worth confirming specifically on any property that has had recent glazing work done to it.

Separating a property fault from a tenant habit

Not every case of indoor drying or a closed vent is a tenant oversight, and not every ventilation shortfall is a property fault, and telling the two apart matters for how a landlord actually responds. A property with working trickle vents and a properly extracting fan that still develops condensation because a tenant consistently dries several loads of washing a week in a closed bedroom with the door shut is a habit issue, worth a straightforward, non-judgemental conversation about drying washing with a window cracked instead. A property where the tenant is doing everything reasonably available to them and condensation still develops is very likely a ventilation fault, a vent that was never actually functional, an extractor drawing insufficient airflow for the room size, and that is a repair responsibility, not a habit to be corrected.

What a landlord can actually verify on a routine visit

A property visit through autumn, before the coldest months properly arrive, is the right point to check every trickle vent opens freely, every extractor fan is running for a reasonable period and actually extracting rather than just making noise, and that no vent, grille or airbrick has been blocked, painted over or covered by furniture since the last time anyone looked. None of this requires specialist tools or a contractor visit on its own, it is a checklist any competent property visit can cover in minutes per room, and catching a closed vent or a weak fan in October is considerably cheaper than dealing with the mould and condensation complaint that follows in December once the same fault has been quietly working against a tenant for two months.

Where this fits into wider property upkeep

Ventilation checks sit naturally alongside a wider condition visit rather than needing their own separate appointment. Our property maintenance service includes a ventilation check as standard on a routine property visit, confirming vents and extractors are genuinely functioning rather than simply present, and flagging anything that needs a repair or a replacement before it becomes a tenant complaint.

Where extractor fans and vents have already accumulated enough dust and grease to need a proper reset rather than a quick wipe, our deep cleaning service covers that level of clean, and for a wider property refresh going into the darker months, our residential cleaning service covers the rest of a property’s condition alongside it.

What the government’s own guidance says

Following renewed national attention on damp and mould in rented housing, Citizens Advice publishes plain-English guidance for tenants covering exactly this problem, setting out that ordinary household moisture production, not an unusual fault or a tenant’s poor housekeeping, is the primary driver of condensation, and that adequate ventilation is the primary defence against it. It is a genuinely useful document for any landlord or managing agent who wants the underlying explanation in full rather than the shortened practical version covered here.

Ten to fifteen litres, every single day

That is the number worth remembering out of all of this, roughly ten to fifteen litres of water vapour produced by an ordinary household every single day through nothing more than breathing, cooking, washing and drying clothes indoors. A property with open trickle vents and properly working extractor fans moves that volume out as fast as it is produced. A property without them is simply storing it, somewhere, on the coldest surface it can find.