Every coastal flat has a mould story. Some are condensation from closed windows and laundry dried indoors, some are a failed terrace membrane, and some are rising damp in a 1930s building with no damp course. The three have different fixes, different payers and very different effects on your deposit.
Condensation leaves black speckles on external walls, in corners, behind wardrobes and on window reveals. It gets worse in winter and better when air moves. Filtration leaves a tide mark, bubbling paint, a patch that grows after rain, often under a terrace or beside a bathroom. Rising damp shows a yellow-brown line at skirting level, a musty smell on the ground floor and salt bloom on the plaster.
A fifteen euro hygrometer and a week of readings beat an argument. Sixty to seventy percent relative humidity is normal on this coast in autumn. Eighty percent indoors with water running down the windows is either a leak or a ventilation problem, and you need to know which before you write the email.
Article 21 of the LAU says the landlord must keep the dwelling fit for use and cannot pass the cost of necessary repairs into the rent. That covers filtration and structural damp. It does not cover a tenant who never opens a window, dries washing indoors and blocks the vents with a wardrobe.
Catalonia adds the cedula d'habitabilitat. A dwelling with serious damp can fail the habitability conditions. If the problem is severe, that certificate is leverage. It is not a magic wand, and waving it before you have evidence usually hardens the other side.
Filtration from a roof, terrace, facade or pipe is the owner's. That means the repair, and normally the redecoration the repair destroys. Condensation is usually the tenant's behaviour, but if the building has no ventilation and single glazing, the cause is shared and a court would look at both.
Do not stop paying rent to force a repair. That turns you from claimant into defendant and can cost you the contract. Pay, document, claim the difference if the home was genuinely unusable, or negotiate a reduction for the works period.
Photos with dates. A written message through the agent, not a phone call. If nothing moves in two weeks, a burofax. A burofax is a letter that proves delivery and content, costs around 20 to 30 euros, and changes the tone of a conversation more than any angry email.
Ask for the repair report and keep it. If the landlord sends a worker, note the date and what was done. If you buy a dehumidifier, keep the receipt. Small money, but it is the difference between a claim and a story.
For a hundred square metre flat, a dehumidifier rated at 10 to 20 litres a day is the standard tool. In a villa, one per floor. The little plastic moisture absorbers are decoration.
Walk away if the damp is structural, the landlord denies it, or the flat has no ventilation and single glazing in a humid corner. Renegotiate if the fix is scheduled: ask for a rent reduction for the works period, or an early exit without penalty.
If you are viewing in summer, look for fresh paint over a patch, a new wardrobe pushed against an outside wall, and the smell of bleach. Come back after rain if you can. Damp is patient. So should you be.
Tell us what you are seeing and when it started. We can point you to the right report, the right letter and the conversation worth having before the deposit is on the line.
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