For landlords and agencies

Renting out a Riviera property: mold, tenants and who pays

Mold in a let property turns into an argument faster than almost anything else, because both sides have a reasonable story. The tenant says the flat is damp. The owner says the tenant never opens a window. Usually there is truth on both sides, and the photos settle it.

Two situations that look identical and are not

Almost every case falls into one of two groups, and they lead to completely different conversations.

Condensation driven by how the property is lived in. A small flat, several people, showers, cooking, laundry dried indoors, windows kept shut for warmth or noise. The building is sound; the moisture produced simply exceeds what gets removed.

A fault in the building. An extract fan that does not work, a cold bridge, a wall against the ground with no ventilation, an infiltration around a window. Here the occupant could air the place perfectly and still get mold.

The distinction matters because the first is a habits-and-ventilation conversation and the second is the owner's to fix. In most real cases you get some of both — a building that forgives nothing, lived in by someone who did not know it needed forgiving.

Reading it from the photos

You can usually tell which one you are dealing with without being there.

Diffuse patches with no sharp edge, in corners, behind furniture, on north-facing walls, worse in winter: condensation. Look at how the place is used and at the ventilation.

A sharp horizontal line across the top of a wall, or a neat border around a window: a cold bridge. Structural, not behavioural.

A stain with a defined edge, darker in the middle, often with a brown or yellow ring, paint blistering: an infiltration or a leak. Structural, and urgent.

Rising from the floor through the first thirty to eighty centimetres, with white powdery salts and plaster lifting: rising damp. Structural, and expensive.

No draw at the extract grille — a sheet of thin paper does not stay against it: the ventilation is dead, whoever lives there. Structural.

Only the first line on that list is about how the property is occupied. The other four are the building.

What to document, and when

Not after the argument starts. Before.

Photograph the property at every changeover, including the bathroom ceiling, under the bath, behind the washing machine and the bottom of the cellar walls. Dated photos of a clean property are worth more later than any statement.
Record whether the extraction works at the start of the tenancy. The paper test takes five seconds and it removes the single most common source of dispute.
Keep it in writing. When a tenant reports damp, reply by message or email rather than by phone, and keep the thread.
Photograph again before and after any treatment, with the itemised quotation. That set is what you send to a co-owner, a managing agent or an insurer.

As a general principle, a structural cause is the owner's responsibility and the way a property is aired is the occupant's. Where a real dispute develops, that principle is worth checking properly for your specific situation rather than settled from a web page — including ours.

Seasonal lets and long lets behave differently

Seasonal lets are occupied intensively and then closed. Summer guests shower several times a day in a flat with the shutters half down, and then the place stands shut. The damage tends to be concentrated in the bathroom and to show up when the property is opened again.

Long lets produce a slower, more even pattern: bedroom corners, behind wardrobes, window reveals, and always worse across the winter. If a long-let tenant reports mold every single winter and never in summer, it is condensation and the building is holding it.

In both cases the useful moment to act is the changeover, when the property is empty and access is simple.

Getting it treated between tenancies

This is the part we do most often for owners and agencies.

Photos in, quotation out. Rate, surface counted, final figure, before anyone travels.
Access with the agency, the caretaker or the outgoing tenant, on a slot that fits the changeover.
Before-and-after photographs plus a line-by-line quotation, in a form that attaches to a report or an insurance file.
A plain statement of the cause, so you know whether you are looking at a ventilation habit or a repair you need to schedule.

That last point is the one owners tend to value most. We say what we saw, including when it means the treatment will not hold until something else is fixed.

What it costs

€45 to €90 per m² of surface actually treated, with a minimum call-out of €250 in zone A and €350 in zone B, travel included. In a damp room the affected areas are treated in full and the rest of the surface gets one preventive pass — treating a single corner of a bathroom between tenants is a false economy, because the next tenant sees it come back.

The full calculation, with coefficients and worked examples, is on the Pricing page. Which zone your property falls in is on the Towns page.

Read next

Mold in a holiday home

Common questions

The tenant says the flat is damp, I say they never open a window. Who is right?

Usually both, partly. Diffuse patches in corners and behind furniture point to condensation and habits. A sharp line along the top of a wall, a border around a window, a dead extract fan or salts rising from the floor point to the building. Photographs of the affected areas and of the extract grille settle it in most cases.

Do you provide something I can send to my insurer?

Yes. A written quotation with the areas and a line-by-line calculation, plus photographs before and after. It is the format we use most often for agencies, managing agents and co-ownership disputes.

Can you work between two tenancies at short notice?

That is when most of this work happens. Send the photos and the dates of the changeover and we will tell you honestly whether the window is workable. Zone A is where we are most often, so lead times there are usually shortest.

Is it worth treating just the visible patch to get through the season?

In a dry room with a localised leak, sometimes yes. In a bathroom or a cellar, no: the spores are across the whole surface, and the next tenant will see it come back within weeks. That is exactly the complaint you were trying to avoid.

Not sure about your case?

Send a photo of the affected area and the town. We reply with the rate, the surface counted and the final figure, before anyone travels. If it sorts itself out without us, we say that too.

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