Home generalRemove black mold - causes of black mold

Remove black mold - causes of black mold

  • Causes of black mold
    • Leaky water pipes
    • Leaking outer walls
    • Wrong isolation
  • Measures to combat mold
    • Black mold: fighting causes
    • Affected interior
  • Tips for quick readers

Black mold is anything but a visual nuisance. The spores of the black mold can cause severe health problems. Therefore, even the smallest mold infestation should be combated immediately. Short-term consequences may be bronchitis or allergic reactions. In the long term, however, permanent contact with black mold is very dangerous. His fight is not easy, but possible.

Mold control on two fronts

Dodging the pure spores of the black mold is virtually impossible. However, the normal concentration in the ambient air is harmless if not affected. Black mold, for example, is very important in the forest because it causes the decomposition of deadwood there. But you can not use it in the house. Before you ask yourself how to properly fight mold, you have to find out where it comes from. Mold always requires three components to form:

  • humidity
  • warmth
  • a breeding ground

Only in the second step, you can actively remove the mold from the house and make sure that he does not come back.

Causes of black mold

The breeding ground of the black mold can be found practically everywhere. Everything that is organic, if only in part, is infested by the black mold. On wallpaper, the wallpaper paste, paint or the paper wallpaper itself is sufficient to serve as a breeding ground for the mold. For example, a tile does not mold up, nor does rock wool or a roof tile. Wood wool or insulation from paper, however, is a feast for the black mold. This can possibly be delayed by impregnation, but not prevented.

Black mold requires organic substances

Molds love warmth . A temperature of 20 ° C is ideal for a fast growth of mold. The spark for the mold is always the uncontrolled spreading moisture. From 80% humidity, it becomes critical and the growth of spores begins.

In a bathroom these unfavorable components inevitably collide: organic material accumulates in the joints of the tiles when showering, the high humidity is inevitable and the ideal temperature of 20 ° is inevitably reached in the bathroom. Above all, silicone joints are endangered by mildew due to their organic components. The manufacturers of bathroom silicones mix their materials with mold inhibiting substances. However, these wash out with time. In most cases, the mold can be treated well. In the worst case, the silicone joint will be scraped out and replaced with a new one. This one has again for several years rest in the bathroom. Unfortunately, mold control is not that easy everywhere. The unwanted moisture can arise in different ways.

Leaky water pipes

A leaking supply or sewer pipe is in any case a great danger for a building. Pressurized water lines, such as those for drinking water, can cause scouring or erosion long before they cause mold. These can quickly endanger the entire statics of a house. Although leaks in sewers are pressureless, their destructive power is no less enormous. This is especially true if one or more winter long leaks go unnoticed. In addition to the mold, the explosive power of freezing water is added.

Mold formation after water damage

As long as it is not made of steel or impermeable concrete, a wall in a house always looks like a sponge. A brick wall can hold hundreds of liters of water before it is noticed. However, there are indicators that can detect a moistened wall before mold is formed. For example, if the window in a room permanently fogged from the inside, you should be attentive. Permanent short circuits in the electrical lines can also be an indication. The room is colder, has a higher humidity and starts to smell "musty". For wall and floor, the moisture can also be felt at some point. At the latest then you should be active.

A common weak point is, for example, the siphon of a bathtub. Modern tubs are usually walled in and tiled all around. If the siphon has been damaged, for example by cleaning, part of the water flows under the bath after each bath. There it seeks its way to the adjacent walls, from where it seeps into the next room.

Leaking outer walls

First of all, rainwater usually does not play a role in the formation of black mold. The moisture entry into a wall must take place permanently and over a longer period of time. Rainwater that pours on a facade, flows off and evaporates again as soon as the sun shines, is therefore negligible in mold growth. However, one problem is missing or damaged gutters. Pointy splashes of water on a facade can again lead to moisture penetration. Standing and pressing from the outside water can be found especially in the basement. In order to keep a basement dry, a great deal of expertise is needed during construction or renovation. For a properly executed cellar, a drainage line, a protective coating, a plastic foil covering (usually bubble wrap) and a correct filling are required. If only one of these components is faulty, this will in most cases lead to water damage in the cellar.

Heat or cold bridges

Wrong isolation

Even if no water can press from the outside and there is no water pipe near a wall, mold can still form on it. The cause of this is then to look in a faulty insulation. Natural humidity always seeks the coldest point on a wall where it condenses. A correctly insulated wall is a largely homogeneous surface for the humidity in the interior. The moisture is distributed evenly and is permanently evaporated again. However, a faulty, damaged or incomplete insulation forms exactly the cold spots that the mold needs. Instead of spreading evenly over the entire wall, the moisture concentrates at the point where the thermal bridge is located. Popular places are here under the window sills, at window frames or in the corners of the ceiling.

Measures to combat mold

If one has established a beginning or already massive spread of black mold, of course first of all the infestation itself must be fought. It is strongly recommended to use respiratory protection and eye protection. All you need is a paper filter mask of class P2. These are available from about 3 euros (eg from the company 3M) in the shop. Skin contact should also be avoided. These are enough simple rubber gloves.

Mold remover

It is extremely important not to use "home remedies" when removing and treating the black mold. The popular vinegar essence has proven to be not only unsuitable for the long term, but even fatal. The aggressive tartaric acid kills 99.9% of black mold reliably. However, it in turn forms a breeding ground for the remaining 0.1%, which is then a culture of particularly resistant black mold.

A professional mold killer does not work on acid but on chlorine . Adequate ventilation of the room in which the mold is to be fought is therefore absolutely mandatory. Professional mold killers cost between 7 and 12 euros in the spray bottle. The procedure is: Spray the mold generously and let it work for about 30 minutes. If the mold is behind a wallpaper, instead of spraying it with a large sponge, it is recommended to wet the entire damaged area generously with an anti-mold solution. This not only fights the mold itself, but binds above all his very volatile spores. Only then with a spatula, a sponge or a cloth to remove the mold from the wall. All absorbent materials (paper towel, rag or sponge) must be sealed in a garbage bag and discarded.

Black mold: fighting causes

When the mold is completely eliminated, the causes must be tackled. Here only consistent search helps to find and eliminate the humidity entry. Insulation defects must be eliminated, leaks sealed and leaks repaired. After repairing the water damage, the wall must dry. This can be accelerated by using a built-in dryer or quite simply with a fully opened heater.


In the described case of leaking siphon under a bathtub, the wall must be pried open on two sides. Only this guarantees a consistent ventilation. A fan in front of one of the openings also accelerates the drying process. The mold not only spreads in the area, it also penetrates deep into the plaster through its fine spores. This is why knocking off the contaminated plaster is the best way to eliminate the mold consistently and permanently. This is also very helpful for the drying of the wall. In most cases, however, a sanding of the paint is sufficient. Once the wall has dried, it can be repainted and wallpapered. If the removal of the plaster has been dispensed with, a coating with mold prevention prevents a renewed infestation.

Affected interior

Drywall walls infested with mold can only be demolished, disposed of and rebuilt. Also, the existing inner insulation of the drywall must be disposed of, even if it consists of non-organic rock wool. The spores can still nest in rock wool and wait for their next activation.

Mold on a wooden framework is particularly problematic. The mold fungus must also be removed from the structure. If it is not enough to plan the upper millimeters, the bar must be replaced. If it is a structural element, it must be done by a professional construction company.

Have high-quality furniture cleaned by a specialist

Black mold can also spread to furniture and floor coverings. Especially in sofas, cushions and armchairs he can nest deeply. Unless it is a high quality seating, disposal here is the most sensible and safest way. There are companies that treat mold with special measures. This includes, for example, aerating with ozone. However, these measures are very expensive and justifiable only for high quality furniture. However, moldy cabinets or shelves can usually be treated well if the mold has not yet penetrated deep into the wood.

A mold attack is an alarm signal and requires quick action. However, in most cases it can be eliminated well and permanently.

Tips for quick readers

  • Pay attention to alarm signals before the mold is formed:
    • musty smell
    • permanently fogged windows
    • cold or damp walls
    • high water bill
  • Treat mold immediately
  • Handle mold with professional means. Do not rely on home remedies.
  • wear mold, eye and skin protection during mold removal
  • find the cause of mold formation before repairing
  • Allow damp walls to dry completely.
  • A mildew is a reason for a rent reduction. Damage to furniture or other furnishings can be regulated by home s insurance.
How much tile adhesive is needed per m² - information on consumption
Build a picnic table yourself - instructions for the table and bench