Damp and mould in a rented home: who has to fix it?

Not all damp patches are the same, and that is where most tenant-landlord arguments start. Before deciding who pays, work out what is happening in that wall.

A leak or a problem with the building

Some damp comes from outside the home or from its installations: a pipe dripping inside a partition wall, a communal downpipe in poor condition, a facade that lets water in when it rains, a badly waterproofed terrace, or damp rising from the ground in ground-floor and semi-basement flats.

Signs that usually point to this origin:

• The patch always appears in the same spot and grows when it rains.
• The paint bubbles, flakes off, or the plaster crumbles.
• The wall feels cold and wet to the touch even in summer.
• The neighbour next door or downstairs has a similar problem.

This is a repair needed to keep the home habitable. As a general rule, that kind of work falls to the owner. And if the source is in the shared parts of the building, it is the owner who should raise it with the residents' association, not the tenant.

Condensation from daily use and poor ventilation

Other damp is created inside the home: steam from the shower, cooking without an extractor, drying laundry indoors, windows that are always shut. That moisture condenses on the coldest surfaces (corners, window frames, the wall behind a wardrobe) and that is where black mould appears.

Signs that usually point to this second origin:

• Mould on cold spots, in the bathroom, and behind furniture against the wall.
• Misted-up windows in the morning.
• It clearly gets worse in winter and improves when you air the place out.

When the problem is purely condensation caused by everyday use, cleaning and upkeep sit with the tenant. That said, some flats have condensation so constant that it points to a shortcoming in the building itself, such as very poor insulation or a bathroom with no ventilation. In those cases the line is blurry, and the sensible move is to talk it through and look for a shared solution.

How to report it properly

• Report it as soon as you see it: the earlier, the cheaper the fix and the less argument about whether neglect made it worse.
• Do it in writing, even if you already mentioned it on the phone. A dated email is worth a lot.
• Say what you see, where, and since when: room, wall, size of the patch, whether it smells or drips.
• Attach well-lit photos and repeat them every few weeks to show how it develops.
• Keep a copy of everything: messages, replies, technician visits, quotes.
• Give access to the property so the problem can be inspected and repaired.

A clear, documented report changes the tone of the conversation: it stops being your word against theirs.

What the tenant can do in the meantime

• Air the flat every day, even in cold weather: five or ten minutes of cross ventilation is enough.
• Use the bathroom extractor and the kitchen hood, and shower with the bathroom door closed.
• Pull furniture a few centimetres from cold walls so air can circulate.
• Avoid drying laundry indoors; if you must, keep a window open.
• Clean surface mould wearing gloves and with the window open, without scrubbing it dry.
• Do not paint over or cover the patch before the owner or a technician has seen it: it erases the evidence and fixes nothing.
• Say in writing if there are babies or people with asthma or allergies at home: it matters when judging how urgent this is.

If it does not get sorted

Follow up in writing with a summary of dates and suggest concrete ways forward: sending a technician, who covers which part, how to make up for a room you cannot use. Most of these cases end in an agreement between both sides.

If the disagreement is about where the damp comes from, an independent technical report usually unblocks things. And if the problem still persists, it is worth getting advice: local housing offices, consumer services, or a professional who can look at your specific case.

Practical tip: take two photos today of the areas most at risk (bathroom, external corners, behind the wardrobe) and save them. If a patch ever appears, you will have the before and after, and that comparison is worth more than any argument.