Musty smell in the apartment without visible mold? - This is what you should do now!

You will find the following content in our article:

• How does the smell of mold in the apartment?
• What does mold smell like?
• Are mold spores dangerous in the home?
• What are the causes of mold growth?
• Where does mold most often occur in the apartment?
• What can I do if the wall is damp but no mold can be detected?
• Increased humidity as the main cause of mold odor in the apartment.
• How can I avoid mold in the apartment?
• How can I remove musty odors from my home?

How does the smell of mold in the apartment?

A mold infestation is often first detected by a noticeable fungal odor. The musty note arises when the mold spores secrete volatile organic compounds of microbial origin, so-called MVOC (English for microbial volatile organic compounds). These are metabolic products or gases that contain, among other things, various chemical compounds such as ketones or alcohols. These MVOCs are not visible to the naked eye, but give a hint of the damage.

What does mold smell like?

There are different types of mold whose odor varies. Mold spores and bacteria mix together, creating different odors: musty, moldy, stale, fungal, sweetish foul, yeasty, dull moldy or damp earthy, for example. Depending on the characteristics of the odor, different sources can be present, which have different effects on the health of the occupants.

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Are mold spores dangerous in the home?

According to the Federal Environment Agency, mold spores are generally present in all indoor spaces, as they contribute to the decomposition of organic materials and are therefore part of our natural environment. These spores are tiny, airborne particles that are present in indoor air, even when they are not visible. They are dormant in dry indoor air. These small particles are particularly tenacious and can survive longer dry periods. However, if the humidity in the room rises, the spores begin to grow and release the typical musty odor that many of us know only too well.

First and foremost, the odor in the home caused by the mold MVOCs reduces the quality of life in the affected rooms. Depending on the extent of the mold infestation, negative health effects can also occur in addition to the musty smell. Particularly sensitive people, such as asthmatics and allergy sufferers, react to mold spores in the air they breathe with a mucousy respiratory tract, a feeling of having a cold, headaches or reduced performance. These symptoms can not only affect general well-being, but can also lead to long-term health problems.

It is therefore of the utmost importance to detect mold growth at an early stage and take appropriate preventive measures.

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What are the causes of mold growth?

In order for molds to grow in buildings, they need a food base. In most cases, an excess of moisture and thus a large food supply causes the infestation.

The most common causes of mold infestation and the musty smell are therefore:

• not completely dried cellulose in wallpaper, wood, plasterboard etc.
• Leaking water/heating & waste water pipes
• severe water damage due to a burst pipe
• Leaky windows or a defective building envelope, through which moisture penetrates from the outside
• Thermal bridges where condensation can form

Where does mold most often occur in the apartment?

Mold is often found where the air cannot circulate sufficiently. In other words, if there is an obstacle in front of a cooler wall or an insulated window, such as furniture or a heavy curtain made of a very tightly woven fabric. This creates thermal bridges, as the warm room air cannot circulate properly. The result: moisture can collect and provides a breeding ground for mold.

This is where you should look for mold:

• behind large-surface furniture such as sofa, cabinets or chests of drawers
• under the bed
• in room corners
• behind curtains
• behind picture frame

Barely used siphons are also breeding grounds for bacteria and mold. Therefore, a musty odor can also emanate from here. You can remove this odor by adding hydrogen peroxide (11.9%) to the siphon. As a preventive measure, you can regularly run hot water through the drain to replace the stagnant water.

If you have localized the smell of mould but cannot see any obvious mould infestation, the spores may have spread behind or under the surface. This is because mold likes to "hide" behind wallpaper, paneling, plaster or baseboards as well as under floor coverings such as carpeting. This could be when the wall feels damp but no mold is visible.

What can I do if the wall is damp but no mold can be detected?

There are several reasons why a wall may be damp and yet no visible mold is present. Possible causes could be

• Condensation: When warm air meets a cold surface, condensation can form. This can occur on external walls, windows or insufficiently insulated areas. The moisture can penetrate the wall and lead to moisture problems.
• Leaks: Leaks in the guttering, leaking roofs, leaking windows or cracks in the walls can lead to water getting into the walls. These leaks can be difficult to detect and slowly leak moisture into the walls.
• Rising damp: Sometimes moisture can rise from the floor through the walls, especially in older buildings that may not have an adequate moisture barrier.
• Faulty construction or insulation: Poor construction or inadequate insulation can lead to thermal bridges that promote condensation and allow moisture to enter the walls.
• Indoor humidity: High indoor humidity, for example due to inadequate ventilation, can also lead to condensation on the walls and cause moisture problems.

It is important to identify the exact cause of the damp in order to remedy the problem effectively. A professional, such as a building surveyor or building inspection specialist, can help diagnose and resolve the problem. A wet wall will likely lead to mold sooner or later, so check your air quality for contaminants and moisture on an ongoing basis with the air-Q.

Increased humidity as the main cause of mold odor in the apartment.

Whereas in the past slightly leaky window frames and joints ensured a constant exchange of air in the room, today's well-insulated windows and thermal glazing keep moisture in the home. If the indoor humidity no longer reaches the outside, it collects on the cool areas of your room walls or windows. If the water flows together and gathers bacteria and co, an excellent food supply for mold is created. The humidity does not even have to come from exceptional situations such as bathing, cooking or drying clothes in the apartment. Even the breath of the occupants is sufficient for increased humidity. Isolated types of building mold already occur at a relative humidity of 70%, the rest at 80%. Therefore, to avoid the cause of mold, you should check the humidity in your rooms.

How can I avoid mold in the apartment?

The most important instrument against a threatening mold infestation is the control of air humidity and demand-oriented ventilation. We have briefly summarized what helps against mold in our tips.

• In the cold months, leave the heat on during the day as well.
• Use a thermostat and ensure a constant room temperature of at least 18°.
• Ensure a regular exchange of air by airing the room on demand. To do this, monitor the humidity in the room with an air measuring device such as the air-Q. The intuitively understandable LED traffic light system allows you to quickly recognize when the humidity in the room is too high, there is a risk of mould and you need to ventilate.
• Don't just tilt your windows to ventilate, open them properly and ideally ensure a draught by means of open doors during shock ventilation.
• Create a wall clearance between exterior walls and large objects of about 5 cm to achieve sufficient ventilation.
• Ventilate even when it rains.
• Do not dry your laundry in one room or ensure sufficient air exchange while doing so and remove the moist air.

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How can I remove musty odors from my home?

If you want to remove the musty odor from a home, this requires a few steps. The first step is to identify the cause of the odor. Then you can remove the musty smell. Our tips can help:

• Ventilation: Ensure good ventilation by opening windows and doors and airing the room frequently. Fresh air helps to dispel the musty smell. We have summarized how proper ventilation works optimally in our article "Proper ventilation: The best tips".
• Check humidity: Musty odors can often be due to excess moisture. Use dehumidifiers to reduce humidity, especially in rooms such as the bathroom, basement or other damp areas.
• Cleaning: Thorough cleaning is crucial. Clean carpets, curtains, furniture and other surfaces that absorb moisture regularly. This way you can remove mold or bacteria that could be causing the musty smell. Use cleaning agents with anti-mold properties.
• Air purifier: An air purifier with an activated carbon filter can help to neutralize odours and improve air quality.
• Natural air fresheners: Use natural air fresheners, such as bowls of baking soda, coffee grounds, or bowls of vinegar to absorb odors.
• Check surfaces: Check walls, ceilings and floors for signs of moisture or mold. Repair and treat any damage or leaks to eliminate the cause of the problem.
• Cleaning carpets & upholstered furniture: Carpets and upholstered furniture can absorb odors. Clean them thoroughly or have them professionally cleaned to prevent odors from building up.
• Air exchange with natural materials: Use natural materials such as wood, bamboo or linen, which are less likely to absorb odors compared to synthetic materials.

If the musty smell persists despite these measures, it may be advisable to seek professional help. This is particularly advisable if there are signs of mold or other serious problems. An air-Q indoor air analysis can provide initial findings to get to the bottom of the source of the rumors. Building biologists and indoor climate experts can also suggest suitable measures to eliminate the causes of odors in the building.