Corrosion resistance of doors

Corrosivity classification indicates the requirements for the resistance of construction products against corrosion/rust infestation. The requirements are based on the corrosion classes C1 to C5 according to SS-EN 12944-2.

Necessary requirements in demanding environments

Design and choice of materials are crucial factors for long lasting doors but also the environment in which the doors are installed.

Doors located in premises with moderate or high humidity and with frequent exposure to water or other liquids are more likely to be subject to rust. Pollution of the surrounding air also matters.

SS-EN ISO 12944-2 presents different corrosion classes based on the location of the construction products. The environmental effects on corrosivity is ranked along a scale from C1-C5 where C1 refers to environments with very little rust influence, such as heated indoor environments like offices, shops and schools.

At the opposite end of the classification scale is C5 – with a high risk of corrosivity – which includes industrial and marine environments – indoors and outdoors – with high humidity and high levels of air pollution.

The corrosivity classes are presented in full in the table below.

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Corrosion resistance of Thermod’s doors

Thermod’s doors are made of fiberglass reinforced, colored polyester with an aluminum door leaf edge. The door leaves are filled with CFC-free polyurethane foam. Common to all materials is that they are insensitive to moisture and can withstand frequent cleaning without damage.

  • The fiberglass laminate is easy to maintain in corrosive environments using rubbing and wax for fiberglass.
  • In-house developed hinges, painted in RAL 9006, counteract rust formations in difficult environments.
  • Natural anodized aluminum with high corrosion class.
  • The range also includes SS1.4404 Acid-proof stainless steel that can be painted in RAL color.
  • Adaptations for fixings to the door leaves for specific HWC products.
  • We offer handles that can withstand corrosion class C1-C5.

Corrosivity classes

Corrosivity - class

Corrosivity of the environment

Examples of typical environments in the temperature-adjusted climate zone (informative)




Very low

Heated spaces with dry air and insignificant amounts of pollution, such as offices, shops, schools, hotels



Atmospheres with low levels of pollution. Rural areas.

Non-heated spaces with changing temperature and humidity. Low frequency of moisture condensation and low level of pollution, e.g. sports halls, warehouses.



Atmospheres with a certain amount of salt or moderate air pollution. Urban areas and slightly industrialized areas. Areas with some coastal influence.

Spaces with moderate humidity and a certain amount of air pollution from production processes, such as breweries, dairies, laundries.



Atmospheres with a moderate amount of salt or significant amounts of air pollution. Industrial and coastal areas.

Spaces with high humidity and large amounts of air pollution from production processes e.g. chemical industries, swimming pools, shipyards.