Mold on walls: why it appears, what you can do yourself and what fixing it costs in Moldova (2026)

Why does mold on walls appear?

Mold needs water, from the air or from the building. The UBA guideline (opens in a new tab) shows that 70–80% humidity at the surface of a material is enough if it lasts: the wall does not have to look wet. The WHO guidelines (opens in a new tab) explain the cold surface: thermal bridges, poor insulation and draughts push the wall below the dew point, and room vapour condenses there.

UBA sorts causes into three groups: the building (poor insulation, thermal bridges, leaks, rising damp), heating and ventilation habits, and accidents. Often two combine: a cold wall and over-humid air. Typical spots in a block of flats:

• Corners of exterior walls: UBA says mold appears there most often, because a corner loses heat on two sides.
• Behind wardrobes and heavy curtains next to an exterior wall.
• PVC window reveals, especially with an uninsulated fitting joint.
• Top-floor ceilings and walls by a downpipe: suspect the roof and gutters.
• Bathroom and kitchen, once the ventilation shaft stops drawing.

Why does mold in an apartment appear in winter?

On 15 October 2026, Termoelectrica (opens in a new tab) announced it could switch on heating in Chișinău’s blocks of flats at administrators’ request. From then on, warm, humid room air meets a cold exterior wall, and condensation collects where the wall is coldest. What makes it worse, per UBA and VEKA:

• New airtight windows, no ventilation. In a poorly insulated old building, UBA says, new windows alone encourage damp and mold: you must air the rooms more often than before.
• Laundry dried indoors. UBA advises against it; if you must, air more often.
• Breathing, showers, cooking. One person releases about a quarter of a litre of water per night (UBA).
• A window left on tilt all day cools the surrounding wall, where condensation then forms.
• A cold room with its door open: humid air from the warm rooms condenses on its walls.
• Furniture against an exterior wall: moisture gets behind it, heat does not.

In a house, water more often comes from outside

For houses, UBA lists driving rain, leaky window joints, roof leaks and damp rising through unsealed masonry and foundations. Stains starting at the plinth point to the foundation’s waterproofing and the slope of the ground; stains under the eaves after rain, to the gutters and roof.

Leaks: the neighbour upstairs, the roof, the pipes

A sharply outlined stain that grows after rain or the neighbour’s shower is not condensation; airing will not stop it. On remont.md, tracing pipe leaks with a thermal camera costs 450–1,000 lei; plumbers’ rates are in our guide to plumbing prices.

What can you do about mold yourself?

1. 1

   Measure the humidity

   A digital hygrometer costs 109–519 lei at maximum.md (10 models). UBA (opens in a new tab) and VEKA (opens in a new tab) recommend 40–60% indoors; the US EPA (opens in a new tab) says below 60%, ideally 30–50%. Keep it near the problem wall, away from radiators.

2. 2

   Air briefly, windows wide open

   In winter, UBA recommends about 5 minutes per room 2–3 times a day with the window wide open, and 5–10 minutes in the bathroom and kitchen during and after showers or cooking, door shut. VEKA (opens in a new tab): open opposite windows for 5–10 minutes, radiator turned down.

3. 3

   Heat every room

   UBA (opens in a new tab): keep the bedroom at 16 °C or more, give rarely used rooms a little heat and a closed door, and keep curtains off radiators.

4. 4

   Move furniture and laundry

   Leave a few centimetres between furniture and the exterior wall and put wardrobes on legs (UBA). Dry laundry on the balcony.

5. 5

   Clean only small patches

   UBA (opens in a new tab): you can clean surface mold under about 0.5 m² yourself if you have no allergy, chronic lung disease or weakened immunity; the EPA’s limit is about 0.9 m². In gloves, goggles and an N95 (FFP2) mask, wipe with household detergent or a little 70–80% alcohol, window open, then dry. Avoid vinegar on plaster.

If patches return after cleaning, humidity stays above 60% despite airing, or the wall feels cold, the cause lies in the building, not your habits.

When should you call a professional, and which one?

UBA says mold over about 0.5 m², or mold inside the plaster, is a job for a firm. Choose the tradesperson by the cause:

• A large patch, swollen plaster, a lingering smell: a finisher who strips the affected plaster, applies antifungal primer, re-plasters and paints; see our plastering and painting guide.
• A cold corner or exterior wall: exterior insulation, by industrial climbers on a block and from scaffolding on a house; see the insulation guide.
• Windows that “weep”, moldy reveals: a window fitter for winter adjustment, seals, insulated reveals and frame vents; see the PVC windows guide.
• No draught in bathroom or kitchen: a ventilation specialist for the shaft, a fan or a heat-recovery unit.
• A stain with an outline: a plumber or, for the roof and façade, the building administrator.
• Unknown cause: thermal imaging shows thermal bridges and wet pipes before you pay for work.

How much do mold treatment and wall repair cost?

Antifungal products do not replace cleaning. UBA says a biocide is generally unnecessary and does not remove mold from the material. The order: stop the cause, strip the plaster, let the wall dry, then prime and paint.

How much do insulation, window work and ventilation cost?

When the wall is cold, cleaning lasts until the next frost. In a block of flats, the usual fix is exterior insulation of that wall by industrial climbers; topmaster.md (opens in a new tab) notes that work at height needs extra equipment or climbers and pushes the price up.

Climbers rarely publish a price per m². A Chișinău listing on 999.md (opens in a new tab), updated 14.10.2026, asks 700 lei “with all materials included” but names no unit. Ask for a written price per m² of façade, listing materials, reveals and travel separately.

Can I insulate just my own flat’s wall?

Yes, but not alone. Under Law No. 187/2022 on condominiums (opens in a new tab), façades, perimeter walls, the roof and the load-bearing structure are common parts (art. 11), and unauthorised work on the façade is banned (art. 72); if the association’s statute allows it, the administrator can impose a penalty of 1–3 conventional units a day. The CNED guide (opens in a new tab) points out that Law No. 75/2015 on housing prohibits insulating a façade without a design permit from the local authority.

1. Write to the administrator and ask whether the building has an insulation project or an approved façade colour.
2. Get the association’s consent: comfort improvements need the general meeting’s prior approval (art. 16).
3. Ask the town hall what the permit requires; only then sign with the climbers.
4. Put the board material and thickness, colour, guarantee and liability for the neighbours’ façade in the contract.

For the whole block, the FEERM (opens in a new tab) programme grants up to 70% of the eligible investment, owners pay 30%, and each measure needs at least 2/3 of owners’ consent. The association applies via its administrator.

Who pays in a block of flats: the association, the neighbour or you?

• Your flat: you maintain and repair it yourself (art. 18(3)): finishes, windows, the bathroom fan.
• Roof, façade, exterior walls, gutters, shared risers: the association is liable (art. 18(9)) and owners share the cost (art. 48). The administrator must arrange urgent work on common parts (art. 45); there is also a repair fund (art. 53).
• A neighbour who floods you: whoever damages other owners must make it good (art. 18(8)). In an emergency, access to a flat for repairs to common parts needs no notice (art. 18(4)); in an abandoned flat, the administrator may enter with two owners and the police (art. 75).
• Insurance: the association may insure common parts if the general meeting approves (art. 61); ask whether your building has one.

In practice: photograph the stains with the date, notify the administrator and neighbour in writing and keep estimates. The WHO splits responsibility the same way: owners answer for construction and upkeep, occupants for their use of water, heat and ventilation.

Is mold dangerous to your health?

The WHO’s 2009 guidelines on dampness and mould conclude that people living in damp or mouldy buildings face a higher risk of respiratory symptoms, respiratory infections and worsening asthma, and the few intervention studies show that removing damp reduces these effects. The WHO estimates that dampness affects 10–50% of indoor environments in Europe, North America, Australia, India and Japan and sets no “safe” level of mold: it recommends prevention.

People with allergies, chronic lung disease or weakened immunity should not clean mold themselves (UBA). If you cough often or have asthma attacks at home, see your family doctor.

What does it cost in total? An example for a two-room flat

Assumptions: a two-room flat on the 6th floor of a Chișinău panel block. The bedroom’s exterior corner wall measures 3.2 × 2.6 m (≈8.3 m²), with mold on ≈1.5 m², and the window has two sashes. Option 1 works indoors; option 2 adds ≈10 m² of façade insulation by climbers.

The cold wall decides it: if the hygrometer reads 40–60% and mold still returns to the corner, option 1 is money lost without insulation. Conversely, insulation without ventilation will not stop condensation on windows.

Chișinău, Bălți, Cahul or a village: what changes?

The platforms publish Moldova-wide prices, with no separate lists for Bălți or Cahul. In Bălți, makler.md carries listings for fresh-air ventilation “against damp and mold” (opens in a new tab) in October 2026, with prices on request.

In villages, the problem is more often damp from the foundation and water from the roof, and a single-storey house needs scaffolding, not climbers. Ask about travel costs and bundle jobs into one visit; see also our guide to finding a reliable tradesperson.

What should you check before paying a tradesperson?