Removing mould from walls: how it’s done
Mould in your flat or house can be dangerous. Comparis shows you how to remove and prevent mould on walls.
25.02.2026
iStock / Vadym Plysiuk
1. Why does mould develop in homes?
Mould spores are natural components of the air. As a rule, this does not cause any problems. However, if they come into contact with a suitable breeding ground and the right growth conditions, mould can develop. Damp and cool surfaces in indoor spaces are particularly susceptible.
Moisture on walls provides mould with an ideal substrate. It can be caused by:
insufficient or incorrect ventilation
poor thermal insulation
water ingress from outside
Without moisture, mould cannot develop.
2. What should I do if I discover mould?
As an immediate step, you should ventilate the room frequently by creating a draught. You should also continue to do this for a few days after the mould has been removed.
If you live in a rented flat, inform the landlord as soon as possible. In the case of condominium properties, you should report the mould infestation to the property manager. Otherwise, you may be held liable for consequential damages. The landlord or property manager is responsible for further clarification.
Good to know: You can also report the first signs of mould to the landlord or property manager. These include, for example, discolouration or a mouldy smell.
For homeowners, the procedure depends on the severity of the mould infestation. You can remove small amounts of mould. If the infestation is more extensive, you should consult a specialist.
Even in the case of a small mould infestation, it’s best to determine the cause first. This will help you avoid long-term problems.
3. Can I remove mould by myself?
You can usually remove minor mould infestations yourself . If the mould is more extensive, you should consult a specialist.
The chart below shows the different categories of mould. Categories 0 and 1 are considered to be minor mould.
4. How can I remove mould from walls?
You can wipe off small spots of mould in corners and on walls with smooth surfaces using water and a little household cleaner. Wipe the area clean. Replace the water several times during this process. Be careful not to smudge the mould spores into other areas. Silicone joints in the bathroom should be replaced.
Rough surfaces should also be disinfected with a bleach solution or ethyl alcohol for disinfection. Important: alcohol is highly flammable. So ventilate sufficiently. Don’t smoke, and avoid naked flames like candles.
Do not use vinegar under any circumstances. The acid is quickly neutralised. The remaining organic components then provide the mould with a source of food. This promotes the growth of more mould.
Good to know: in the case of very light mould, plastic gloves are sufficient for protection.
As a tenant, you should, for legal reasons, not remove category 1 mould yourself yourself. Inform your landlord about the mould.
If you own your home, you can remove medium-level mould yourself. However, it is important that no at-risk person is living in the property. In that case, hire a professional.
Moisten the mouldy area with water. This is important to impede the spread of the mould spores. Alternatively, you can also glue wallpaper base paper (or waste paper) to the mouldy area. The spores then become bound to the paste.
Remove the wallpaper and, if necessary, the plaster beyond the affected areas. Disinfect the area with bleach solution or ethyl alcohol if necessary. Plaster and re-paper the area.
In the event of more extensive damage: hire a professional
Important: have you noticed the damage is worse than first thought while trying to remove the mould? Then get a specialist. They can reassess the problem.
Fitted furniture, e.g. a wardrobe cabinet
Fitted furniture can be cleaned with a damp cloth. However: if the mould has penetrated the furniture, dispose of the affected parts. This might include the back wall of your wardrobe, for example. Tape over the part with foil beforehand to prevent the spores from spreading. You can tell where mould has penetrated, for example, by severely mouldy or swollen chipboard panels.
Furniture made of solid wood can usually be cleaned. Mould is usually only superficial.
Upholstery and upholstered furniture
In many cases, you cannot clean upholstered furniture without great effort. This is because the mould may have penetrated deep into the upholstery. It’s best to dispose of the affected furniture.
If a piece of upholstered furniture is only contaminated, you can vacuum it thoroughly using a special vacuum cleaner. «Contaminated» means, for example, that the furniture was in a room with mould on a wall. Then dispose of the vacuum cleaner bags.
Comparis tip: The Federal Office of Public Health (FOPH) offers the brochure «Caution – Mould» to download free of charge. Here you can find detailed information on how to prevent and remove mould.
Removing mould: what do I need to bear in mind?
Before removing the mould, you should protect yourself sufficiently. This means: Wear
disposable gloves
A pair of safety goggles
A mask. This should be at least an FFP2 mask. A mask that meets the FFP3 protection standard is better.
A disposable protective suit. If you don’t have one, wash your clothes thoroughly afterwards.
Cover objects or remove them from the room before removing the mould. Keep the door closed, so that the spores don’t spread to other rooms.
When working, open the windows to ventilate and work with as little dust as possible. This means stirring up as little dust as possible. This can be done, for example, by moistening the area to be removed.
When should I not remove even small mould infestations myself?
You should not remove the mould yourself in the following cases:
You have a respiratory disease, for example asthma.
Your immune system is weakened, for example due to a transplant, HIV or cancer.
You suffer from an allergy to mould.
When you’re finished, dispose of your protective clothing, used rags and waste. Clean the room thoroughly, ideally with a damp cloth. After the mould has been removed, ventilate regularly for a few more days. This reduces the amount of spores and mould components in the indoor air.
Important: Do not use dehumidifiers until the mould has been removed. Otherwise, the number of mould spores will increase.
5. Extensive mould growth: Hire a specialist
Large-scale and repeated mould infestations should be removed by a specialist. This is because the roots of the mould sometimes extend a few centimetres deep into the wall. They are not killed by removing and painting them over. If you only paint over the mould, it often reappears after some time.
Mould infestation with no identifiable cause
Can you identify the cause of the mould infestation not recognise it, you should also consult a specialist. This also applies to small and moderate mould infestations.
Do you suspect significant defects? In that case, experts in structural damage and building physics can assess whether further renovation measures are necessary are necessary.
How often do you need to ventilate to prevent mould?
You should ventilate regularly throughout the year. This is especially important when your heating is on. Also ventilate well in rooms where you produce a lot of steam. This includes the kitchen and bathroom, for example.
The humidity should be between 30% and 50% . On very cold days, a humidity of 40% is ideal. If windows are fogged up or condensation has formed, the humidity is too high.
Important: Windows in the tilted position can promote mould growth, especially in winter. This is because walls and floors near the window become cold. This increases the risk of moisture due to condensation.
Therefore, always ventilate by fully opening windows and doors.
6. When is mould dangerous?
Moisture and mould can put your health at risk. How dangerous mould is depends, among other things, on your immune system and any pre-existing conditions.
As a rule: The more extensive the mould growth, the greater the health risk. However, it’s also possible that you may not notice any signs of illness despite mould.
What are the symptoms to look out for with mould?
Some symptoms of mould infestation are:
Irritation of the skin, eyes and respiratory tract
Nasal congestion
Scratchy throat
Coughing and wheezing
Rash
Irritated airways can lead to chronic coughing and asthma in the long term. In addition, mould can trigger allergies and be the reason for frequent colds. In the long term, irritation of the airways can lead to a chronic illness.
People with severely weakened immune systems severely weakened immune systems can become seriously ill due to mould. For example, it can trigger infections. If you have asthma, mould can lead to attacks.
Yes, among other things, mould can cause headaches, among other things. This is especially true for sensitive people, children, and allergy sufferers.
If the headaches occur together with other symptoms of illness of a mould infestation, you should have them checked by a doctor. This is because these symptoms can also be signs of an allergy to house dust mites or other substances.
7. What types of mould are there, and how dangerous are they?
There are different types of mould. Some of them can be distinguished by colour. Some types of mould are more dangerous than others.
Most types of mould cause the typical symptoms of mould-related illness. However, depending on the type, the symptoms can also be more serious.
Important: The list only refers to types of mould in apartments and houses. It doesn’t address food mould.
Risk to health: Seriously harmful to health. Depending on the type of black mould, it may cause kidney disease and serious infectious diseases, for example. Other species mainly affect the respiratory tract. Some toxins produced by black mould are also carcinogenic.
Preferences: walls, wallpaper, plastered walls, ceilings and tile joints
Other: It can consist of various types of mould. It’s comfortable in temperatures between 6 and 45 degrees Celsius.
Risk to health: Typical mould-related symptoms.
Preferences: corners of ceilings and floors, in niches and behind furniture on external walls.
Other: Often difficult to see. It can be recognised by the musty, unpleasant smell. Woodlice and silverfish often appear in rooms with white mould.
Important: White mould can be confused with efflorescent salts on the outside wall of the house. Before removing it, check whether it really is mould.
Risk to health: Spores can infect the lung tissue and damage it in the long term. The toxin formed tends to weaken the immune system rather than inflicting direct harm.
Preferences: Joints, under flooring and behind wall cladding. Usually found in the bathroom and kitchen.
Other details: Often green in the middle and grey to white on the outside.
Risk to health: Particularly hazardous to health. It releases the poisonous aflatoxin into the environment. This can cause liver cancer and heart failure, for example.
Preferred environments: Damp corners, cotton fabrics and upholstered furniture.
Other details: Often more ochre or brown than yellow. Due to high hygiene standards, it’s rather rare to find this mould in Switzerland.
Risk to health: Typical mould-related disease symptoms.
Preferred environments: Paper wallpaper, cardboard boxes and wood panelling. It is usually found in the bathroom and kitchen.
Other details: The red colour can take on different shades and intensities. Red mould is also often found on grain and in flour.
8. Frequently asked questions about mould on walls
Whether you can remove mould from walls yourself depends on the severity of the mould infestation. Whether you can remove mould from walls yourself depends on the severity of the mould infestation. As a homeowner, you can usually remove minor mould yourself. However, tenants should inform the landlord or property manager.
In the event of a more extensive mould infestation, you should always call in a specialist. You should consult a specialist. They can assess the mould and remove it professionally.
Vulnerable persons should not remove mould themselves. Groups at high risk include:
People with respiratory diseases
People with weakened immune systems
People with an allergy to mould
In principle, you can remove black mould yourself. However, the requirements for this are as follows:
You are the owner of the property. Tenants should inform the landlord or property manager.
It is a minor mould infestation.
You are not at risk due to a pre-existing condition.
Air purifiers can not remove mould infestations. However, they can filter mould spores out of the air. Therefore, you can use an air purifier to support other measures to prevent mould.
A mould infestation should always be removed and, if necessary, the cause investigated.
A dehumidifier does not help if there is already a mould infestation. However, it can help prevent mould. This is because mould thrives on moisture – and you can control moisture using a dehumidifier.
Good to know: Ideally, the humidity in your home should be between 30% and 50%.
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This article was first published on 24.10.2024
