Firstly, it resists rain, snow, and high humidity to prevent insulation failure. The thermal insulation capacity of rock wool depends on still air trapped in its internal porous structure. Without hydrophobicity, moisture from precipitation or humid conditions seeps in, replacing the still air. Since water’s thermal conductivity is roughly 25 times that of air, this drastically reduces insulation efficiency. Moreover, infiltrated moisture evaporates slowly, leaving the panels persistently damp and further impairing their performance. Hydrophobicity, however, causes water to form beads and roll off the surface, preventing penetration and maintaining stable insulation.​

Secondly, it combats freeze-thaw cycles to avoid physical damage. In cold regions or during seasonal transitions, temperatures fluctuate around 0°C, creating freeze-thaw cycles. If rock wool absorbs water, the moisture freezes and expands at low temperatures, widening internal pores; when thawed, the pores fail to fully recover. Repeated cycles lead to cracking, pulverization, and structural loosening. Hydrophobicity minimizes moisture infiltration, fundamentally reducing such damage and preserving the panels’ structural integrity.​

Thirdly, it inhibits mold growth and corrosion by isolating humid environments. In persistently damp areas like basements and exterior wall bases, water-absorbent materials often foster mold. Additionally, moisture can seep into building structures, corroding metal components such as steel bars and keels. The hydrophobicity of rock wool reduces surface and internal moisture retention, lowering mold growth conditions and protecting indoor/outdoor health. It also prevents moisture from contacting metal parts, reducing corrosion and extending the building’s lifespan.​

Fourthly, it maintains structural stability in extreme weather. Heavy rain, typhoons, and coastal salt spray subject roofs and exterior walls to constant moisture impact. For roof insulation, hydrophobic rock wool prevents rainwater absorption and subsequent "weight gain," avoiding structural deformation from excessive load. For exterior walls, it blocks moisture infiltration through the panels, preventing issues like dampness, hollowing, and peeling. It also mitigates erosion from salt-laden moisture in coastal environments.​

Finally, it cuts maintenance costs and extends service life. By addressing moisture-related problems—insulation failure, structural damage, and mold/corrosion—hydrophobicity eliminates the need for frequent rock wool replacement or repair, as well as reducing secondary maintenance for walls and roofs. For commercial buildings and industrial plants, this significantly lowers labor and material costs. Over the building’s entire lifecycle, it also prolongs the insulation system and main structure’s service life, enhancing overall cost-effectiveness.​