Interior doors made out of wood and wood-based materials are exposed to various different stresses and strains due to the wide variety of installation locations within the building and their high level of use. Products labelled with the RAL Quality Mark for Interior Doors made of Wood and Wood-Based Materials meet these high quality standards: The material used to produce these doors must be able to withstand the various climatic and physical conditions that it is exposed to on both sides of the door over many years. In particular, the material used for entrance doors to apart-ments not only has to be able to withstand various climatic conditions without suffering any dam-age but it is also essential that it can absorb sound and protect against burglaries.

In contrast, bathroom and kitchen doors face a completely different type of challenge. The material used for these doors has to be able to cope with higher levels of humidity and withstand both heat and also moisture without suffering any damage. And it is also important not to ignore the physical appearance of the doors: The raw material used for the surfaces of the door leaves must be re-sistant to stains, scratches and impact. Finally, the robustness of the door frames also plays an im-portant role. The frames are subjected to rigorous usage tests to verify that the material used to produce them can also withstand the stresses and strain of long-term use.