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Mold grows through a spoiling peach. The individual recordings were made every 12 hours - over a period of six days.

Molds , visibly also called mold , are a systematically heterogeneous group of filamentous fungi in microbiology , the majority of which belong to the taxonomic groups of the Ascomycetes and Zygomycetes .

The great majority of molds live inconspicuously as saprobionts in certain ecological niches . Some types of mold are of particular importance to humans as human parasites and pathogens of infectious diseases and as the cause of notifiable plant diseases and mold toxins in spoiled food. However, molds are also food processors and biological sources of antibiotics and cholesterol-lowering drugs.

Building mycology deals with the prevention of mold damage and its remediation.

Features and Distribution

Molds often appear as a colored coating on spoiled food (e.g. bread, fruit) as well as on damp walls or wood. An adequate supply of moisture is generally a prerequisite for the formation and spread of mold infestation . Either on the infected substance itself, in the form of regular condensation or through significantly increased humidity . The colonization of organic substances by molds often favors a number of subsequent putrefaction processes .

Mold spores spread through the air and form a mycelium when they find suitable living conditions. The mycelium consists of microscopic, multiply branched fungal threads, the hyphae , which spread out in a circle.

All molds feed on organic molecules (e.g. carbohydrates , fats , proteins ). They are therefore among the heterotrophic organisms. Nutrients in food, in the soil, in wood , excrement , grains of dust , leather and occasionally even in plastics serve as substrates .


Due to the lack of criteria for the systematic classification of molds (generally with Fungi imperfecti ), no comprehensive system could be established in the past that is based on the ancestry and relationship of the groups. Molecular genetic methods are used today to uncover the relationships between species, so that the earlier division of the asexual stages into the division of the Fungi imperfecti ( Deuteromycota ) has become obsolete.

Since many species have so far been classified primarily on the basis of morphological characteristics, the classification is not yet complete (see also: List of Fusaria ).

A distinction is made between the following genera of molds:

Acremonium Dematiaceae (black fungi) Phoma
Alternaria Eurotium (v. A. = Aspergillaceae) Rhizopus (bread mold)
Aspergillus (watering can mold) Fusarium Scopulariopsis (v. A. = Microascaceae)
Aureobasidium Monilia Stachybotrys
Botrytis Mucor (head mold) Stemphylium (v. A. = Pleosporaceae)
Chaetomium Mycelia sterilia (proof?) Trichoderma
Cladosporium Neurospora Ulocladium (= Pleosporaceae)
Paecilomyces Wallemia
Curvularia Penicillium (brush mold)

Construction / structure

With the microscope you can see that the mold consists of numerous fine threads. These mycelia are the actual molds. They can look whitish, greenish, gray or other colors. In contrast, mostly only the spore carriers serving for reproduction , the sporangia, are clearly visible . These form an important distinguishing feature between the individual species. According to the shape of the spore carriers, head mold , brush mold and watering can mold can be distinguished.


The reproduction usually takes place in an asexual way via spores , which are produced at the end of spore- bearing structures. The spores are at mold-forming hose mushrooms  - such as Aspergillus or Penicillium  - conidia called. In order to allow a large number of these conidia to arise, the mycelial threads generate special hyphae, the conidia carriers, after a while . These differ depending on the species and often consist of densely branched hyphae that look like a small forest when magnified slightly. Spores ( conidia ) are formed on the outer ramifications, the sterigmas , which protrude outwards in a chain-like manner . At this stage the mold takes on a dusty texture.

In the mold- forming Mucorales , which belong to the Zygomycetes , the spores are not pinched off at the end of the conidium carriers, but are often produced in thousands in sporangia , which are formed as spherical swellings at the end of the sporangia carriers .

Molds need above all nutrients and moisture to grow . In addition, the oxygen supply , the temperatures , the pH value ( basic or rather acidic environment inhibits) and other factors influence the growth of mold.

Since mold can be found almost everywhere, their spores are usually always present in the air. These are harmless to the majority of people if they do not occur in large numbers, but in certain cases they can trigger allergies or occasionally lead to serious illnesses in people with a weakened immune system .

Molds as beneficial and pests as well as pathogens

Mold colonies in Roquefort cheese
Mold on cream cheese
Salami with harmful mold
Bread with mold
Early mold on an orange

Examples of useful and harmful fungi

Mold refers to the surface change caused by mold, the mold rot visible to the naked eye ; this usually consists of (often pigmented ) conidia or sporangia carriers and the mycelium .

Of the 130,000 species of fungi, only a few can be used for dairy farming and are therefore suitable for the production of cheese as ripening organisms. These mushroom species used in the dairy industry differ from harmful cultures in that they only give the cheese their specific aromas, but are completely harmless to the human organism. In order to promote the formation of mold, certain types of cheese are pricked with broad needles during the ripening process, i.e. pricked, so that oxygen can penetrate the cheese through the needle channels and promote and accelerate the formation of mold.

The benefits and harm of mold can be closely related:

  • Antibiotics such as penicillin are produced as metabolic products of molds such as Penicillium chrysogenum (former name Penicillium notatum ). Even before that (around 1948) moldy bread was already used in the treatment of purulent wounds.
  • Aspergillus niger can cause a variety of diseases in humans and will thrive even in extreme pH levels, but is used industrially to make citric acid .

Modes of damage, mold infections

A mold can damage people and pets through its cell components , metabolic products and spores or at least be a nuisance to them. Unwanted consequences can consist of considerable odor nuisance, allergic reactions and - possibly fatal - poisoning. In extreme cases, molds (especially Aspergillus fumigatus , but also rarer fungi such as zygomycetes and fusaria since the beginning of the 21st century) attack and destroy body tissue with fatal results.

Pronounced (invasive) mold infections have a high mortality rate, require months of cost-intensive therapy and often secondary prophylaxis. Molds such as Aspergillus niger , Aspergillus fumigatus and most of the yoke fungi ( Zygomycota ), which are known to be the cause of fatal ( lethal ) diseases, occur practically everywhere in the soil and in the potting soil as natural saprotrophic ("putrefactive") organisms without noticeably harm. The danger posed by mold depends on the one hand on the concentration of active substances (of metabolic products, cell components or spores) when they come into contact with affected people or pets. People and animals are exposed to relevant concentrations of this kind when they ingest mold-infested food (poisons), stay in infested rooms (spores, poisons) or are themselves infested ( infection : mycoses ; poisons, allergenic cell proteins ). On the other hand, the risk of allergic reactions or mycoses only affects correspondingly sensitive or immunocompromised individuals. AIDS , diabetes mellitus (type 1), leukemia , neutropenia or therapy that suppresses immune reactions ( immunosuppression in organ transplantation , autoimmune disease , allergy ) or impairing therapy ( chemotherapy or radiation for cancer ) can cause such an immunodeficiency. The mycosis is then an opportunistic infection .

Molds can through the carbohydrates of their cell wall ( glucans ) toxic effect or if they mycotoxins as metabolic products ( metabolites produce), in particular liver-damaging and carcinogenic aflatoxins . So was u. a. the Aspergillus flavus mold - for example through the aflatoxins B 1 and B 2 it produces - suspected to be the medically understandable cause of the " Pharaoh's curse ".

A Aspergillosis is a fungal infection caused by a kind of the genus Aspergillus , in some cases internal organs can infect ( invasive aspergillosis ) - and can lead to death. A repeated galactomannan screening, possibly also examination procedures such as bronchoscopy and biopsy, are part of the pathogen detection or diagnosis and monitoring of a therapy . If a lung infection is suspected, it is recommended that a high-resolution HR computed tomography scan be performed instead of a conventional X-ray . An aspergilloma is aspergillosis in which a "ball of fungus" settles in a body cavity (often the lungs). The spores formed on the surface of the sphere pose a risk . In the case of aspergillomas or residual symptoms that still require treatment after therapy, surgical treatment may be required.

According to UBA guidelines , p. 10 f. or UBA brochure , p. 5, inhaled spores and metabolic products of mold can trigger allergic and irritating reactions in humans. It is believed that this basically applies to all molds. They are not only able to do this when they are alive, but also dead (while infections only come from living molds). The allergic bronchopulmonary aspergillosis is a special form of aspergillosis . It affects the respiratory tract / lungs and further leads to bronchial asthma .

A zygomycosis is a mycosis caused by a type of yoke fungus ( Zygomycota , class Zygomycetes ; mostly order Mucorales (head mold-like), hence also mucormycosis). These include u. a. the genera Mucor ( head mold ) and Rhizopus (bread mold, especially the Rhizopus stolonifer, which lives in food and in the ground ). The fungus spreads through the bloodstream, damages them, interrupts the supply of tissues (especially the face ) and leads to death in a few days (in 4 out of 5 cases). Zygomycosis, especially with such a fatal course, only threatens if the immune system is severely weak . Because of the unclear or unspecific symptoms , mycoses are often not easy to recognize.

The seldom occurring pathogens causing mold infections include zygomycetes as well as Acremonium and Paecilomyce species.

A Phaeohyphomycosis is an infection of the skin with different molds, which occurs mainly in domestic animals.

The drug (antimicrobial) treatment and secondary prophylaxis of an infection by mold are carried out with antimycotics . During the treatment of a mold infection, steroids and other immunosuppressants (see above) should be discontinued or reduced as far as possible.

Mold on food

Skipping behavior of mold on nectarines
Close up of a mold on a nectarine

Apart from the above-mentioned beneficial fungi (“ noble mold ”), molds spoil food in terms of sensory factors, especially in terms of taste, and harbor the health risks mentioned above, particularly through mycotoxins . These mold toxins are released into the food and can spread in it, especially quickly in foods that contain water. They cannot be removed by boiling, frying, baking, souring, drying or freezing. Mycotoxins can be distributed unnoticed in the food by means of primary contamination during processing of contaminated raw materials, or by means of secondary contamination they can be introduced directly through the growth of mold on the food.

Food contaminated with mold must be disposed of. Cutting only part of it is generally not enough, as the mold spreads invisibly to the human eye. Only with some foods, in which neither the fungus nor the toxins have spread widely, can the mold and a generously dimensioned area around the infected area be removed. This concerns:

  • Solid jam with a sugar content over 60 percent. Sugar in these concentrations has a preservative effect .
  • Even in hard cheese , mold cannot spread much - you can cut off the mold generously and consume the rest of the cheese.
  • The growth of mushrooms in air-dried sausage and ham varieties is also inhibited, such as in many types of salami .

Molds can grow at temperatures from 0 to 60 ° C, the fastest between 20 and 25 ° C. Mold on food can continue to grow at temperatures as low as −10 ° C. Storage in the freezer at −18 ° C is enough to stop mold growth.

Mold on paper

Molds can form on paper in particular when dust-laden or soiled archive material is exposed to a relative humidity of over 60% that is too high or when there is increased object humidity due to water damage. Temperature fluctuations associated with a change in humidity or inadequate or incorrect ventilation can also cause mold growth.

Mold in buildings

Formation of mold in buildings

Moldy ceiling
Mold growth on walls


As mentioned above, many types of mold live almost everywhere. Mold spores are transported through the air. It is therefore obvious that spores of various types of mold can be found in every building. The decisive difference between building parts in or on which the mold grows and those where it does not grow is to be found in the living conditions that the molds find there.

Individual (physical) factors that promote the appearance of mold in buildings or without which mold cannot occur are discussed in Sedlbaur / Krus 2003 :

There is usually food available in buildings, for example through biodegradable organic substances that have been introduced by the materials used in construction chemicals , for example additives in concrete mortar or plastering mortar , wall paints ( emulsion paints ), wallpaper and wallpaper adhesives , wall coatings and floor coverings, in the condensates separated in the indoor air ( Enumeration there ), dust and dirt residues. In addition to parts of the building such as walls, ceilings, window frames, furniture, stored clothing, books, etc. can also be attacked. Overall, the suitable substrate is practically always available, as is oxygen, and UV light does not play an essential role indoors. Humidity and temperature are mainly effective in their combination as relative humidity as follows.

Moisture as a growth factor for mold

Mold growth usually takes place on a suitable surface if the adjacent air layer has at least 80% humidity over a period of five days .

The warmer the air, the more water it can absorb (see humidity ). The water activity - the a w value - is biologically relevant. The water activity that occurs in the room on the surface of a component depends on the moisture content of the room air and the surface temperature of the component. In the cold season, the mold-favoring surface temperature, especially in room corners, behind cupboards, etc., is typically well below the air temperature in the room. An a w value of 0.8 (relative humidity 80%) or more is a typical prerequisite for mold indoors if it is present for a longer period of time. Individual types of building mold occur from a relative humidity of 70%, from 80% almost all others.

Common causes of mold indoors are (summarized):

  • when (warmly heated) air absorbs a lot of moisture and the water vapor condenses on colder walls, components and furnishings,
  • if increased humidity is not ventilated away and the moisture on the walls, components and furnishings cannot dry off,
  • if the thermal insulation is permanently moistened by condensates, capillary cracks in the outer layer or driving rain and moisture that has penetrated here too can only insufficiently dry off (because, for example, a moisture- and vapor-tight facade paint was chosen),
  • if building moisture does not dry sufficiently.

Insufficient drying leads to permanent wetting, wetting leads to an increase in the thermal conductivity in the building material (synonymous with a reduction in the thermal insulation effect), this leads to the formation of thermal bridges or cooling of components and ultimately condensation of room moisture on these cold components. Damp components store more heat and dissipate it and the transmitted room heat better. Both heat effects mean that after a night-time temperature reduction, the reheating of such walls can take longer than with non-wetted parts of the wall.

There are essentially three types of water entry into the building structure:

Moisture content of building materials

During construction, building materials are processed that have a certain (excess, releasable) residual moisture. These can be, for example, concrete mortar and plastering mortar , building materials that have been manufactured using water, such as sand-lime bricks , aerated concrete bricks or gypsum and cement screeds , but also the moisture from natural stones . Fresh wall and ceiling plasters also gradually release their water into the environment as they dry. Even pre-dried construction wood is still so damp in its core that it loses around 10% of its weight over the years.

Moisture caused by the unplanned ingress of water into a building
  • defective water pipes z. B. heating pipes, hot, cold or waste water pipes, connecting hoses for wash basins, washing machines and dishwashers, clogged drains, clogged drainage , ...
  • Penetration of meltwater or rainwater due to defective roof sealing and drainage, leaking masonry, standing water on the house wall, etc.
  • Penetration of drifting snow
  • Accidents: fire fighting water, flooding, etc.
  • Wetting due to condensation or, in the case of thermal insulation materials, seepage of dew through capillary cracks and lack of drying
  • Sooting a chimney
Humidity of the room air as a result of normal use

The main cause of mold in indoor spaces, which has triggered a lot of (legal) disputes between tenants and landlords in the recent energy-saving era , is the inevitable indoor humidity caused by the normal use of indoor spaces. The humidity in the air does not only come from bathing , showering and cooking , but also from the breath and sweat of the residents, especially in bedrooms and children's rooms, drying damp laundry and damp mopped floors and the perspiration of plants.

The formation of condensation from the indoor air indicates the risk of mold growth . However, condensation forms in places with a relative humidity of 100%. Mold cannot grow there. However, in such a room there will also be surfaces on which a relative humidity of between 80 and 90% persists for some time and on which mold will therefore appear.

  • In buildings that were erected up to around 1975, condensation on windows and the inside of outer walls was already known. However, the formation of mold was prevented by permanent natural ventilation. The air exchange required for room hygiene was ensured by the fact that windows and doors, due to their construction, dehumidify the room air unnoticed . In order to save energy , the window constructions in many of these buildings have been replaced by windows that are so tight that the exchange between moist indoor air and dry outside air now has to be brought about by ventilation . The replacement of radiant heating (individual stoves in the apartments) with convection heating ( central heating systems ) in conjunction with incorrectly installed thermal insulation composite systems also led to increased mold damage in apartments. Depending on the weather (especially in summer), however, ventilation can also increase the humidity of the room air (especially in cellars ); then heating (or even a technical dehumidification process) is more appropriate.
  • With the same water content in the room air ( absolute humidity , H 2 O approximately in g / m³), ​​the dew point of the room air on various component surfaces is below the lower the temperature . There, the water vapor condenses to liquid moisture, i.e. the formation of dew (strictly speaking, all condensable air pollution, which all have different dew points, from evaporated stearin from burned candles to acidic rain moisture , etc.) condenses . This is why it is often advised to keep heating on the one hand, even when you are absent, and on the other hand to stop ventilation in good time so that room walls and furniture do not cool down ( sudden ventilation instead of tilting windows ). - The surface temperatures generally differ between different parts of a room, in particular with the proximity to a thermal bridge (insufficient thermal insulation) or a cold water pipe, also between different areas of an apartment or house depending on the use / heating. The relative humidity fluctuates within a room or - with open passages (doors) - between areas of the apartment / house. The relative humidity on the surface of the threatened nutrient substance is relevant for mold growth.
    Loss of condensation and mold infestation in the area of ​​a linear thermal bridge
  • Leaky vapor barrier films on interior insulation or in roof structures allow moist room air to diffuse (for the small extent, see Breathing Wall # Moisture Removal ) and subsequently condense in components or immediately resublimate to ice . In this way, the air humidity can be increased even in unheated rooms ( e.g. loft ) and mold growth can be enabled (see thermal insulation ).
    Mold growth on a sloping roof caused by a hole in the vapor barrier film
  • Furniture standing against the wall can have a similar effect to interior insulation without a vapor barrier. It prevents the inside of the wall from heating up and thus shifts the dew point towards the side of the room. If the water vapor is not adequately shut off, condensation will occur more frequently.
  • The room air near a thermal bridge , i.e. a place where the heat is transported outside more quickly, cools down more quickly and the moisture that is now condensing is deposited as condensation on the wall. If there is no ventilation, the temperature drops and the relative humidity at the cool wall area increases. For this reason, too, moisture condenses with the following formation of mold, especially where closed furniture is too close to outside walls and ventilation cannot be guaranteed.
  • In addition to preventing the exchange of air by means of denser joints ( see above ), ( subsequent ) thermal insulation measures usually consist of inserting older windows with windows with better insulating frames and glass . This can lead to the fact that the room air increasingly condenses on remaining thermal bridges ( e.g. window reveals ) and causes mold there - cf. Ventilation and thermal insulation. In general, it is noticeable that mold only appears indoors after subsequent thermal insulation measures. After the renovation, landlords / builders can try to avoid arguments with residents by pointing out the changed required ventilation behavior (e.g. information sheet). However, the responsibility remains with the landlords / builders with regard to the insulation of all thermal bridges (see above). If there is mold on the window reveal z. B. to check whether the soffit insulation was carried out correctly.
  • A case based on a judgment by the Hamburg Regional Court can serve as an example: Double-glazed windows were installed in a poorly insulated house. The landlords hand out a leaflet about ventilation behavior to the tenants. Nevertheless, moisture damage is increasing, and mold is growing on the ground floor. A lawsuit by the landlord against a corresponding rent reduction is essentially dismissed. The district court wrote in the justification: "The tenant's obligation to adapt his living behavior to structural changes finds its limit where the level of what is reasonable is exceeded. [...] In terms of building physics, rented rooms must be designed so that the furniture is spaced apart from the wall of only a few centimeters, as is generally guaranteed by the presence of a rubbing strip, moisture damage cannot form through condensation [...]. As far as ventilation is concerned, the tenant cannot be asked to ventilate thoroughly several times throughout the day just to compensate for a deficiency in the building fabric. "


The consequences of mold infestation in buildings range from the destruction of individual components (e.g. wooden window frames) to the infestation of everyday objects through to the health impact of residents. For people who are allergic to mold , prolonged stay in mold-infested rooms can lead to allergic reactions.

Evidence and assessment

A clear indication of mold infestation in buildings is the appearance of the typical dark spots and / or a musty (earthy) odor (see also trichloroanisole ).

Analytical evidence can be provided either via air analyzes (testing for certain metabolic products of the fungi), material samples of the infestation or via house dust tests . A study published in 2009 suggests that the ergosterine content in house dust can be used as a quick method for indoor mold exposure .

In most cases, an analytical examination and determination of the fungus can be dispensed with. An assessment of the visible mold infestation can be classified and roughly assessed according to the following criteria:

Cat. feature Rough assessment of structural damage and health risk.
0 Traces of superficial mold growth with the following size: up to 100 cm², in one place, only in one room.

There are no mold stains (discoloration), a history of water damage, or other signs / indications that could indicate a problem

Normal condition or minor damage

Unproblematic in terms of health and building physics

1 Superficial mold growth or mold stains in one place, only in one room with the following extent:
  • up to 0.5 m² with isolated vegetation
  • up to 100 cm² with dense vegetation

There is no history of water damage or other signs / indications that could indicate a problem

Low to medium damage

The situation must be viewed critically in terms of preventive healthcare and must be improved.
In terms of building physics, the situation is not very problematic, but the condition can worsen (sometimes within a short time).

  • Isolated mold or mold stains on an area of ​​more than 0.5 m² or:
  • dense, flat mold growth on an area of ​​over 100 cm² or:
  • Mold growth in deeper layers or:
  • Mold growth or mold stains in several places in the same room or in different rooms, up to a total of 10 m² or:
  • distinct smell of mold without visible mold growth
Huge damage

The situation is unacceptable in terms of health care and there is a need for rapid action. In terms of
building physics, the situation is often problematic and the condition can worsen further.

  • Isolated mold or mold stains on an area of ​​over 10 m² or:
  • dense, extensive mold growth on an area of ​​over 2 m²
Extreme damage

As long as the type of mold is not known, an acute health hazard must be assumed!
Without immediate action, the room should no longer be entered unprotected.

Note: Category 0-2 corresponds to the recommendations of the health authorities in Germany (LGA cat. 1-3) and Switzerland (BAG cat 0-2). However, many practitioners miss an extended category. That is why the LGA / BAG categories are supplemented with a category 3 by many experts.

Mold can endanger the health of employees in the workplace . There are no medically-toxicologically based limit values ​​for the contamination of the breathing air at the workplace with mold. There is a large number of measurement methods, the results of which are usually not comparable with one another.

The working group "Job Evaluation" set up by the Committee for Biological Agents (ABAS) of the Federal Ministry of Labor and Social Affairs (BMAS) is dedicated to this problem and accompanies the development and validation of standardized measuring methods for mold and other biological agents in the air at the workplace.

The Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) has published a measurement procedure for determining the mold concentration in the air at the workplace in the IFA work folder “Measurement of Hazardous Substances”, which can be ordered as a special print.

Treatment (remediation)

In the household

The mold visible on the inner wall surface of outer walls is usually formed by condensing humidity in the winter months. In unheated basement rooms, on the other hand, mold is more likely to form in the warm half of the year, when warm outside air leads to the formation of condensation on the cold basement walls. Superficial mold can often be removed with a damp cloth.

To prevent the formation of new mold in the short term, denatured alcohol ( ethyl alcohol ) or the more expensive 70 percent isopropyl alcohol can be applied twice to the surface . Since alcohol evaporates easily, it should not be sprayed. Cleaning agents containing hypochlorite ( chlorine cleaning agents ) and (3 percent) hydrogen peroxide , which can also bleach remaining stains, are similarly effective .

Applying a borax solution and painting over the affected areas with alkaline mineral paint such as lime paint and silicate paint have a longer-term effect . If possible, these wall paints should not contain any organic resins, which are often added to simplify processing and used as binders in emulsion paints .

To avoid mold growth in the long term, the moisture content of the air and the building structure must be kept low, for example by taking the following measures:

  • Consistent intermittent ventilation of living rooms with high levels of moisture (bedrooms in the morning, living rooms during the day and evening, kitchen after cooking, shower rooms after showering, laundry drying rooms). In winter, the dry outside air can absorb a lot of moisture after warming up and help dry out damp rooms.
  • Use of a condensation dryer or an exhaust air dryer with removal of the moist exhaust air to the outside,
  • Installation of a controlled living space ventilation or a condensation dehumidifier for the shower,
  • (Temporary) heating of cold wall surfaces by means of radiant heating ,
  • Use of radiant heating such as underfloor , wall and ceiling heating instead of conventional radiators (convection heating), in which the (moist) indoor air is warmer than the surface of the outer wall in winter, which means that the dew point is not reached and the humidity can condense,
  • Closing basement windows in summer. Warm, humid air flowing in there condenses on cold cellar walls, and then mold and mold stains appear.

In construction

Device for measuring humidity

The visible mold has to be removed, not only disinfected (killed), since killed particles of mold and spores also retain their allergenic potential. Mold damage of categories 2 and 3 must be carried out by specialist companies taking the necessary protective measures ( black and white zone separation , protective suits, respiratory protection, etc.) into account .

A distinction is made between the following objectives and measures against existing building mold; Combinations must be considered on a case-by-case basis:

  • make biological "harmless" ("kill"); this is about ligation
    • further metabolism (i.e. also further formation of toxins),
    • further spread of the infestation (of the mycelium),
    • further formation of spores

or even an inactivation / destruction of the spores so that they can no longer become biologically active. It must be noted that mold spores (relatively easy to control) and bacterial endospores (very difficult to control) are not identical to one another. So there is no need for explicitly sporocidal disinfectants to combat mold spores.

  • make visual "harmless" ( bleach );
  • actual (i.e. physical) "removal" of the mold or its residues after other treatment. This typically means removing the infested substrate , including plaster or other building materials.
  • Prevent renewed mold growth.

It should be noted that a “dead” mold that has not been completely removed can also release toxins or allergens into the room air (see “ Damage ”).

Chemicals can mold mold in the short term and i. General remove only on the surface. As a rule, they are only used by specialists as part of a comprehensive renovation. Fungal or fungicidal - fungicidal or fungistatic - have a. a. the following chemicals and methods:

Hydrogen peroxide , sodium hypochlorite , chlorine dioxide and peracetic acid are oxidizing agents . They also destroy mold spores and, as a bleaching agent, discolor the covering so that it may not have to be completely removed (porous surfaces). Ethanol is not sporocidal , rather it is used to loosen and wipe off all mold deposits on smooth surfaces.

For small areas and up to approx. 2 cm material depth:

For larger areas and greater material depths (also thick bars, etc.):

  • Microwave generators, with which the necessary temperature is reached inside the wood: wood-destroying organisms are killed, time and energy expenditure are high.

Fungal chemicals are also used prophylactically to prevent future mold growth. When exposed to light and heat, these can decompose and become ineffective. In addition, causal treatment always has priority, in particular moisture must be prevented. - Quaternary ammonium compounds ("Quats", QAVs ) act i. General only fungistatic ; however, this is sufficient to prevent the germination of spores and the formation of new mold. They are much more stable than the more aggressive and sporocidal oxidizing agents sodium hypochlorite and hydrogen peroxide . Therefore, they are z. B. used as an admixture to the paint for (additional) prevention of mold.

In order to remove the breeding ground (moisture) from the mold, the wall can be drained and the moisture removed from the room air. The dehumidification can be performed by various means, methods and procedures. The simplest method is correct ventilation , a distinction is made between intermittent and continuous ventilation, with open ( cross ventilation ) or closed doors. If this does not help, electrical or chemical room dehumidifiers can be used.

To be distinguished from building mold

  • The dry rot - a tube fungus as the cep , no mold - overcomes even meter long dry routes for water to nutrient (wood) for transport. It also penetrates masonry. The infected wood can be pressed in by hand. The dry rot can therefore destroy buildings.
  • As Black dust or fogging is an often sudden, referred especially in winter or after renovations occurring blackish discoloration of interior walls, whose origin is still unclear.



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Building mold

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  • W. Isenmann, R. Adam, G. Mersson: Moisture phenomena in inhabited buildings . Causes - consequences - renovation - appraisals - rent reduction. 4th completely revised and significantly expanded edition, Verlag für Wirtschaft und Verwaltung Wingen, Essen 2008, ISBN 978-3-8028-0560-8 .
  • V. Möcker, H.-J. Moriske, R. Szewzyk: Help! Mold in the house. (PDF file; 3.9 MB) Causes - Effects - Remedy. Federal Environment Agency , Berlin 2004 ( PDF file, 1.94 MB ).
  • H.-J. Moriske, R. Szewzyk: Guide (PDF file; 1010 kB) for the prevention, investigation, assessment and remediation of mold growth in interior spaces (“mold guide”). Federal Environment Agency , Berlin 2002. ( PDF file, 1010 KB. )
  • Klaus Sedlbauer, Kurt Kießl, 2002: New insights into the assessment of mold and the status of standard processing . Fraunhofer Institute for Building Physics , Holzkirchen; Bauhaus University Weimar.
  • Klaus Sedlbauer, Martin Krus, 2003: Mold from a building physics point of view , Fraunhofer Institute for Building Physics, Holzkirchen, quantitative analysis of the physical prerequisites for mold growth; with tables and graphs.
  • State Health Office Baden-Wuerttemberg: Molds in interiors - Evidence, evaluation, quality management, December 2004.
  • Brochure Moisture and Mold . Consumer advice center for energy. Retrieved February 6, 2015.
  • Wolfgang Maes: Stress from electricity and radiation. Electrosmog, radioactivity, indoor climate, toxins in the home, particles, fungi . 4th edition, Institute for Building Biology + Ecology, Neubeu 2000, ISBN 3-923531-22-2 .
  • W. Maes: Electrosmog - home poisons - mushrooms . Building biology - practical help for everyone. Haug, Heidelberg 1999, ISBN 3-7760-1599-3 .
  • DIN-Fachbericht 4108-8 (2010-09): Thermal insulation and energy saving in buildings - Part 8: Avoidance of mold growth in residential buildings

Health aspects

  • HJ Bünger: Health risks from inhalation exposure to mycotoxin-forming molds . In: Hazardous substances - Keeping air clean 65 (9) / 2005, pp. 341–343. ISSN  0949-8036
  • GM Fischer, N. Hollbach, C. Schmitz, W. Dott: Airborne molds in the human environment - relevance to health and risk assessment options. In: Hazardous substances - keeping air clean. 65 (9) / 2005, pp. 335-340. ISSN  0949-8036
  • L. Roth, H. Frank, K. Kormann: Poison mushrooms. Mushroom poisons. Molds. Mycotoxins. Occurrence, ingredients, fungal allergies. ecomed, Landsberg 1990, ISBN 3-609-64730-2 .
  • R. Keller, K. Senkpiel, W. Butte: Molds and their secondary metabolites ( MVOC ) in air samples from unpolluted apartments. Hazardous substances, keeping air clean 67 (3), pp. 77–84 (2007), ISSN  0949-8036
  • General biological and medical aspects indicated in the present Wikipedia article are also dealt with in the guidelines and (more briefly) in the brochure of the Federal Environment Agency in a generally understandable manner or further elaborated.

Web links

Commons : Schimmel  album with pictures, videos and audio files
Wiktionary: Schimmelpilz  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ P. Sitte, H. Ziegler, F. Ehrendorfer: Strasburger. Textbook of botany . 33rd edition. Urban & Fischer, 1991, ISBN 3-437-20447-5 .
  2. Werner Heinz: infections caused by fungi. In: Marianne Abele-Horn (Ed.): Antimicrobial Therapy. Decision support for the treatment and prophylaxis of infectious diseases. With the collaboration of Werner Heinz, Hartwig Klinker, Johann Schurz and August Stich, 2nd, revised and expanded edition. Peter Wiehl, Marburg 2009, ISBN 978-3-927219-14-4 , pp. 269–287, here: 281–287.
  3. Meredith Blackwell: Eumycota: mushrooms, sac fungi, yeast, molds, rusts, smuts etc. February 14, 2005, accessed on April 6, 2007 (English).
  4. Classification of molds into genera and species
  5. a b c d Species Fungorum - Search Page. Retrieved March 6, 2019 .
  6. Axel Arthur Brakhage: Systemic fungal infections caused by Aspergillus species: epidemiology, infection process and virulence determinants . In: Current Drug Targets . tape 6 , 2005, p. 875-886 , PMID 16375671 .
  7. Gottfried Eysank: Letter to the editors. In: Würzburg medical history reports. 22, 2003, p. 609 f.
  8. a b c Werner Heinz: infections caused by fungi. 2009, p. 281.
  9. Werner Heinz: infections caused by fungi. 2009, p. 285 f.
  10. Werner Heinz: infections caused by fungi. 2009.
  11. Mold on food ( Memento from September 28, 2007 in the Internet Archive ) (PDF file; 39 kB)
  12. Working aid dealing with mold in archives (PDF; 789 kB), accessed on July 13, 2013
  13. ^ Klaus Hermann Ries: Installation of Windows , In:, saved in September 2005; The last saved version of the website dates from January 2006.
  14. ^ Building damage collection, Volumes 2 and 3
  15. Martim Saar: Ventilation in old buildings , worksheets of the Bavarian State Office for Monument Preservation, Munich 2002, p. 2
  16. E.g. UBA guidelines p. 3, 19, 21.
  17. UBA brochure , pp. 14, 16; or UBA guidelines , pp. 19, 21., Table 2, p. 16 at least demonstrate how the drying effect of ventilation decreases with increasing outside temperature.
  18. UBA brochure , p. 16 below, or UBA guide , p. 19 left column.
  19. See again UBA brochure p. 14, UBA guide , p. 21, 23, as well as mechanical ventilation and shaft ventilation
  20. So z. B. Casting mold (PDF; 59 KB).
  21. ^ For example, UBA guidelines , p. 50.
  22. Regional Court Hamburg , judgment of September 26, 1997, file number 311 S 88/96, NJW-RR 1998, pp. 1309-1310 = BeckRS 1998, 03595 [there with the complete facts] (after appeal against a similar judgment by the Hamburg district court) .
  23. ^ LG Hamburg, NJW-RR 1998, pp. 1309-1310 (1310).
  24. ^ Building damage collection, Volumes 2 and 3.
  25. Michaela Haas Through Schimmel and Hell , Süddeutsche Zeitung, 7./8. October 2017 p. 47
  26. Guide to the prevention, investigation, evaluation and remediation of mold growth indoors. Ed .: Umweltbundesamt, Berlin 2002; Guide to preventing, investigating, evaluating, and remedying indoor mold growth
  27. Ilka Toepfer, Werner Butte: Chemical indicators for mold in house dust . Hazardous substances - keeping air clean 69 (3), pp. 91–95 (2009), ISSN  0949-8036
  28. Beware of mold - A guide to moisture problems and mold in living spaces Ed .: Federal Office of Public Health, Bern 2009; (PDF; 2.1 MB)
  29. Markus Durrer: Microbiological pollution of indoor spaces. (PDF; 330 kB) Indoor climate plus, RKP-DOK30, 2010.
  30. a b German Statutory Accident Insurance e. V. (DGUV): Measurement procedure for biological agents in the air at the workplace. (PDF) Retrieved February 22, 2019 .
  31. ^ Institute for occupational safety of the German Social Accident Insurance (IFA): Biostoffe. Retrieved February 22, 2019 .
  32. My afternoon | Archive test: Even home remedies defeat mold , In:, January 9, 2014
  33. ^ Annette Schmaltz: Market | Archive mold removal in the bathroom , In:, April 12, 2019
  34. The architect Konrad Fischer , who specializes in the renovation of old buildings, recommended (during his lifetime) as the first choice " washing surfaces with cheap household spirit " and advised against "other poisonous substances or acetic acid". Konrad Fischer: Mold on the wall - cause and remedy 6 [12]. Accessed December 31, 2019 .
  35. ^ Means against mold. What kills the fungus , Stiftung Warentest , 20002
  36. Molds. P. 137 ( limited preview in Google Book search).
  37. Jörg Dressler (j.dressler [at], Peter Koger: Sporen und Sporizide - the special duel in the sterile area. Steriltechnik 1/2003, GIT Verlag (, Darmstadt; Pp. 29-32.
  38. Room dehumidification: to lower the air humidity. Retrieved January 29, 2017 .