Mould in interiors

Mould is an important and natural part of our living environment. If it appears in interiors, however, then it becomes a hygienic problem that should not be underestimated. In case of high permanent concentration in the air or reduced body‘s defences (e.g. in children or immunodeficient people), mould usually classified as harmless can impair health.

In addition, mould damage always indicates a higher occurrence of humidity, which can, in turn, also lead to considerable building damage and loss of value.

Mould Formation

The basic prerequisite for mould growth in buildings is – apart from sufficient nutrients – the presence of humidity. The decisive factor here is not relative indoor humidity but how humid the wall or ceiling surface is. If it exceeds 70% and/or temperature is lower than 12.6°C, the danger of mould formation increases. Accordingly, the following use-related and structural causes of mould growth in interiors are summarized:

Humidity Sources as Causes of Mould Growth

  • Excessive humidity release in the room (e.g. caused by cooking, showering, house plants)
  • Incorrect, insufficient or no ventilation at all
  • Insufficient heating
  • Poor heat insulation level, (geometric) thermal bridges
  • Higher heat transfer resistance (caused by incorrectly placed furnishings, for example)
  • Window installation during refurbishment
  • Humidity in the structural design (caused by insufficient driving rain protection of the facade, no construction waterproofing or a defective one, new construction humidity, for example)

The fact is that conventional interior paints that have film preservatives are not able to withstand microbial colonisation in the long run because most of the active ingredients used in these products are “used up“ after a short time, precisely in the highly stressed areas. What remains is an unprotected coat of paint that  can be infested by mould within a short time.


If there is mould growth, measures aimed at eliminating the damage should be taken at once. At the same time, the cause of the growth should always be determined and remedied as far as possible. In large mould damages, we especially recommend the inclusion of experts for carrying out the necessary root cause analysis and action planning.

BIONI has collaborated with specialists and experts in the fields of microbiology and structural physics for many years to selectively work out and show the customer the best possible solution even in the most diffiicult cases.

If the recommendations of the German Federal Envuironmental Agency are followed, if mould is present in interiors, the  renovation effort should be adjusted to the extent of the damage and the type of room use. Whereas mould growing on smaller areas (< 0.5 m²) can be removed by the non-professional with suitable products during renovation, an expert (consultant, specialised company) should be hired to remove mould from larger areas (> 0,5 m²).


Based on the latest scientific knowledge, BIONI was able to develop interior coatings that not only boast previously unrivalled long-lasting protection against mould growth but also meet the highest requirements of hygienic room air safety.

This was accomplished by combining the patented SILVER SYSTEM TECHNOLOGY and silicate-containing light fillers that influence the microclimate on the coating surface to the disadvantage of fungal spores. Thus, BIONI interior coatings are particularly suitable for use in interiors affected by and at risk for humidity and mould, and clearly superior to conventional wall paints and coatings:

Comparative Test

Untersuchung: ADVISAN DR. MISSEL GmbH

Test Species


Aspergillus Niger no growth
Penicillium chrysogenum no grwoth
Cladosporium cladosporioides no grwoth
Acremonium strictum no grwoth