Professional mold removal: Why painting over it only moves the stain

The dark stain behind the bedroom wardrobe disappeared after painting over it. Four weeks later, it reappeared, this time larger. This is how many homeowners describe their first experience with mold. Standard wall paint makes the infestation invisible for a while, but it doesn't eliminate it.

This is precisely where cosmetic measures diverge from remediation. Anyone who wants to get rid of mold permanently needs to know why it's growing in that particular place. The crucial question, therefore, isn't what can be used to cover the stain. It's: How deep is it?

If you want to know how deep the infestation is, then contact MVM AGThe on-site assessment is the first step.

Why and how does mold develop?

Mold spores are present in every home, even a newly renovated one. They only become a problem when they find enough moisture and a nutrient-rich surface. Wallpaper paste, emulsion paint, drywall, and dust provide these nutrients. The fungus hardly needs light or oxygen.

The moisture rarely comes from outside. It's generated inside the room, for example, through showering, cooking, or breathing. When this warm air hits a cold wall surface, it drops below the dew point and condensation forms. That's why condensation so often occurs on exterior walls, in room corners, and behind furniture. In older buildings, rising damp from the masonry is also a common factor, which is why it often appears there first. reduce humidity in old buildings leaves before any renovations even begin.

Why does the mold return after painting?

Painting over the mold only covers up the result, not the underlying cause. Only a portion of the colony is visible anyway, as the fungal network grows into porous materials such as plaster, gypsum, wallpaper, or grout. As long as the wall surface continues to fall below the dew point, the mold will reappear in the same location.

This leads to the most important decision: On a thick coating, the mesh tends to stay on the surface, while in soft plaster it penetrates deeper. If the substrate is sound, one treatment followed by a new coat of paint is sufficient. Otherwise, the material must be removed.

When should you consult a specialist company?

Mold is not a fringe problem. According to Federal Office of Public Health In Switzerland, dampness and mold occur in every fourth or fifth household. A small spot on a silicone joint in the bathroom may seem harmless, and often it is. The problem is that it's almost impossible to tell from the outside whether it will remain just that small area. The visible growth doesn't indicate how far the mold has already penetrated the material.

"Mold is almost always larger than the naked eye shows. We can only see how far it extends with a professional measurement."

Oliver Emmenegger

Customer service, surface and mold remediation expert

Therefore, an assessment by a specialist company is worthwhile sooner than most people think. It answers the crucial question that determines everything else: whether treatment is sufficient or whether material needs to be removed. Those who renovate based on suspicion alone either remove too much or too little.

The situation is clear as soon as the infestation affects building components. With drywall, insulation, or wood, dismantling is likely. The same applies if the mold reappears after cleaning, as this indicates a problem with the building structure.

How does professional mold removal work?

The process always follows the same sequence because each step builds upon the previous one. MVM AG It works according to this grid, whether it concerns an apartment or a commercial property.

1. Root cause analysis and measurement. A Wall moisture measurement This reveals whether the infestation is caused by a structural defect, water damage, or condensation. Without this step, any further measures remain a guessing game.
2. Isolation of the work area. When removed, spores are released into the room air. Dust protection and controlled airflow keep them out of adjacent rooms.
3. Assessment of load-bearing capacity. This is where it's decided whether the existing substrate can remain. If it's sound, treatment follows. Otherwise, wallpaper, soft plaster, or affected drywall will be removed.
4. Cleaning and drying. The substrate is cleaned and dried under controlled conditions. Reconstruction only begins once the residual moisture content is correct.
5. Construction with mold-resistant coating. The final step is a coat of paint that prevents new growth instead of covering it up.

Before the first step is taken, they check Experts from MVM AG On-site assessment to determine the extent of the infestation. This will determine which of these steps are necessary for your property.

What are the benefits of a mold-resistant coating?

Mold-resistant coatings inhibit the growth of mold spores and thus prevent re-infestation. Depending on their composition, different mechanisms of action are employed.

It is important to use suitable, tested products that are appropriate for inhabited spaces and can be applied to sound surfaces. These products can also be used to treat vulnerable areas preventively.

What role does the subsoil play?

The type of substrate determines the extent of the remediation. The same area can require treatment in just a few hours or dismantling over several days. The following overview shows the distinctions experts make during their on-site assessment.

The price is also determined by this assessment. A simple cleaning is cheap, but it's a repetitive process. If someone cleans three times and then needs remediation, they'll pay for the remediation separately. That's why the analysis comes first, not the quote.

How do you keep the wall dry after the renovation?

After the renovation, the way the wall is used determines whether it remains dry. Therefore, the following is important: Moisture protection in Winter, when warm indoor air meets cold exterior walls and condensation forms.

Three habits are most effective: Ventilate several times a day by opening windows fully for a few minutes, especially after showering and cooking. Heat rooms evenly, as moisture condenses on the walls in cold rooms. Position furniture a little way away from exterior walls to allow air to circulate behind it. A dehumidifier can also help in bathrooms and basements.

Conclusion: Mold removal starts with the cause, not the paint.

Mold doesn't disappear simply by covering it up. It disappears when the moisture that feeds it is gone. That's why every professional mold removal begins with a measurement, not with a product. This is followed by containment, assessment of the substrate, controlled drying, and a coating that prevents new growth.

The MVM AG Serves both private clients and property management companies as well as commercial properties from its various locations. Emmen, Zurich, Zug, Sursee, Stans and Meggen Painters and plasterers work in the same company, ensuring that the substrate, treatment, and paintwork are compatible. If you want to have your mold permanently removed, feel free to contact us.

Frequently asked questions about mold removal