Northern weather conditions place severe demands on industrial structures and waterproofing. Constant exposure to moisture, freezing temperatures, and temperature fluctuations puts mechanical stress on materials. When temperatures fluctuate around freezing, traditional protective coatings are put to the test. This often leads to microscopic cracks through which water can penetrate the structure.

Protecting industrial buildings, bridges, retention basins, and roofs requires solutions that perform reliably even during the coldest months. Seamless coating technologies have proven effective when structures require complete watertightness and a long service life. The following section examines, from the perspectives of physics and materials science, how an elastic polyurethane coating behaves in northern weather conditions and how it differs from other protective solutions.

Temperature fluctuations in northern climates place high demands on the flexibility of waterproofing systems

Concrete and steel structures change shape depending on the ambient temperature. When autumn moisture condenses in the structure’s pores and the temperature drops below freezing, the water expands by about nine percent as it freezes. This phenomenon creates high hydraulic pressure inside the structure. If the protective coating does not flex in response to the movement occurring beneath it, hairline cracks will form. Through these cracks, water can penetrate unimpeded deeper into the structure.

Particularly challenging are situations where the weather rapidly shifts from mild conditions to severe freezing temperatures. The material must withstand sudden mechanical stresses without compromising its adhesion to the substrate. Many traditional bitumen- and epoxy-based insulation materials become brittle at low temperatures. When the substrate contracts in the cold, the brittle coating cracks, and during the subsequent mild spell, meltwater is free to damage the structures.

An elastic polyurea coating offers an excellent solution for this. Its chemical structure ensures high elasticity, which is maintained even at temperatures as low as tens of degrees below zero. The material can stretch to many times its original length without being damaged. The coating reliably bridges thermal movements and hairline cracks in the underlying concrete. Since water cannot reach the surface of the metal or concrete, corrosion and deterioration of the structure are halted.

What is the difference between polyurea and polyurethane?

In design and construction, the terms “polyurea” and “polyurethane” are sometimes confused, even though they are two materials with different properties. Both are polymers, but their chemical reactions and behavior during installation differ significantly.

The curing of polyurethane is based on a reaction between isocyanate and polyol. The reaction requires a catalyst to proceed and is sensitive to ambient moisture. If there is moisture in the air or on the substrate at the time of application, the water reacts with the isocyanate to form carbon dioxide gas. The gas creates small bubbles in the coating, which weaken the film’s strength and impermeability. The drying time for polyurethane is generally measured in hours or days.

Polyurea, on the other hand, is formed when isocyanate and amine react with each other. The reaction occurs without an external catalyst and is extremely fast. When the components meet in the high-pressure spray nozzle, they react immediately, and a chemical bond forms within seconds. Thanks to this speed, humidity or temperature do not have time to interfere with the process. The coating is rain-resistant almost immediately after spraying. The surface can be put into use quickly, which minimizes production downtime.

How long does a polyurea coating last?

In industrial protection, the service life and the payback period are important metrics. Polyurea coating provides long-lasting and durable technical protection instead of ordinary paint. Based on independent studies and practical experience, the service life of a properly installed system in demanding applications exceeds 25–30 years.

Its long service life is due to the material’s excellent mechanical wear resistance. The surface withstands abrasion, impacts, and continuous heavy loads without the protective film thinning or becoming damaged. For example, forklift traffic or heavy machinery does not easily damage the surface, which saves on maintenance and repair costs in the long run.

In addition to mechanical stress, the coating is resistant to UV radiation and chemicals, such as dilute acids, alkalis, and road salt. Aliphatic polyurea grades retain their color in direct sunlight without becoming brittle or chalky. The material is therefore a cost-effective choice for applications requiring long maintenance intervals and a reliable level of protection.

What are the installation requirements and potential risks associated with polyurea?

Achieving a smooth and durable protective coating requires precise application conditions. Because the material cures in seconds, it does not level out surface irregularities in the same way as slow-drying coatings. Therefore, surface preparation must be done very carefully before spraying begins.

The most important factor in installation is the dryness of the substrate. If there is too much moisture inside the concrete, the water will tend to evaporate as the temperature rises. This evaporation can cause the coating to peel or bubble, which weakens adhesion. The relative humidity of the concrete must therefore be within the permitted limits. A suitable primer is always used during installation to seal the pores of the substrate.

Mechanical pretreatment is an essential step in the process. Cement paste and contaminants are removed from concrete surfaces by diamond grinding or shot blasting. Steel surfaces, on the other hand, are blast-cleaned to the required cleanliness level (such as Sa 2½). A rough and clean surface ensures that the polyurea coating forms a strong bond with the substrate.

Does polyurea coating require hot work?

In industrial and commercial buildings, occupational safety regulations are strict. Traditional waterproofing work is often done using bitumen membranes, the installation of which requires gas torches. In such cases, the work is always classified as hot work, which increases fire risks, requires separate permits, and often involves hours of post-work monitoring after the workday has ended.

Polyurea coating offers a significant safety benefit in this regard. Although the material components are heated to approximately 70–80 degrees in the equipment prior to spraying, no open flames or external heat sources are used during the installation itself. In cold-application spraying, the reaction and curing occur purely through chemical processes.

When no hot work is required, this saves time and reduces administrative work. Plant operations can continue uninterrupted in adjacent areas without any fire hazard. This solution reduces insurance risks and makes it easier to fit the project into the plant’s daily operations without costly special arrangements.

A seamless protective coating extends the service life of structures and prevents frost damage

The seamless design effectively prevents damage to concrete and steel structures. When there are no joints on the surface, water and chemicals cannot penetrate the structure. In northern climates, this prevents frost damage to concrete, as water cannot freeze inside the structure. The protective membrane retains its flexibility even in severe cold and adapts to the substrate’s natural thermal movements, extending the service life of the entire building or equipment.

A successful outcome requires an experienced contractor with the right equipment and sufficient resources. The quality of the subgrade work, the right conditions, and precise equipment control are crucial to ensuring that the coating achieves the desired service life of several decades.

Kotek Factory Service Oy is a nationwide and reliable partner for industrial surface treatments and waterproofing. As a major player in the industry, we can guarantee that agreed-upon schedules are met and warranty matters are handled responsibly. Our extensive experience and technical expertise ensure that even the most demanding industrial projects are coated with professional skill, from design to the finished surface.