Water Repellents Fight the Good Fight


By Peter DeNicola, Evonik Corporation

What is the root cause of nearly all issues that damage mineral building materials?


Protecting porous mineral building materials with water-repellent sealers offers a safeguard against the slew of problems that come with water intrusion. It also extends the service life and look of the building, reduces maintenance costs and even reduces energy costs by increasing thermal efficiency.

Water is kept out with Protectosil water repellent products.

Preventing Water Intrusion

When an unprotected building substrate, such as concrete, brick masonry or natural stone, is exposed to the elements, such as rain or any water with dissolved pollutants, the moisture is absorbed into the substrate. That water will remain in the structure, leaving the material subject to damage from freeze-thaw cycles during the winter months.

The freezing will cause tiny cracks to form, and when the sun warms the substrate surface, the water and dissolved pollutants will work their way to the surface of the substrate. The salt will crystallize, causing efflorescence and salt bursts, further damaging the building.

However, when building materials are protected with a hydrophobic water repellent, the repellent chemically bonds with the substrate, shielding it from the effects of water. Instead of being absorbed into the building, the water droplets sit on the coated surface of the substrate, where the sun’s heat causes the water to evaporate naturally. This not only keeps the substrate problem-free and mildew-free, but it also keeps the surface looking better longer, because the repellent also protects against UV rays.

See how the process works, shown here with the Protectosil line of hydrophobic water repellents from Evonik:

Thermal Efficiency

While water repellents are well-known for fighting corrosion and water intrusion, a lesser-known benefit is a savings in energy costs, as thermal conductivity is influenced by moisture content.

In general, the higher the moisture content in concrete and other building materials, the higher the thermal conductivity. Water repellents, such as silane sealers, can reduce the thermal conductivity of a building by reducing the moisture content in the substrate, thereby reducing energy consumption. Additionally, this reduction complements energy-saving initiatives as a whole, as the use of silanes can yield credit points for structures that owners want to qualify for Leadership in Energy and Environmental Design certification.

A recent study prepared by Wiss, Janney, Elstner Associates Inc., entitled, “Impact of Silane Sealers on Thermal Conductivity of Building Materials” compared moisture content and thermal resistance between concrete walls treated and not treated with silane sealer. The study found that the treated test walls exhibited approximately 3.5 percent higher thermal resistance than untreated walls after a 41-day rain event simulation test. Researchers estimated that such treatments would have an even more pronounced effect with thinner walls, estimating that a 4-inch-thick treated wall could show as much as a 6.4 percent higher thermal resistance than an untreated wall of the same thickness.

Protectosil products reduce energy and maintenance costs.

Overall Sustainability

In addition to energy savings with regard to the structure, promoting sustainability in the surrounding environment is also a benefit when using Protectosil. The predominantly low-VOC, solvent-free line of products has earned a silver-level Cradle to Cradle Material Health Certificate for its Protectosil BHN water repellent, demonstrating that it’s possible to safeguard the environment, reduce energy costs and preserve building materials — all while battling moisture.

Protectosil SC 100 and Protectosil ANTIGRAFFITI SP were used to protect wall art from water damage, staining and graffiti in the new World Trade Center subway.

*Claims or positions expressed by sponsoring authors do not necessarily reflect the views of TPC, PaintSquare or its editors.

Peter DeNicola, Evonik Corporation

Peter DeNicola holds a B.S. degree in chemistry from Rutgers University. He has been with Evonik Corporation since 2000, starting in R&D for the Organic Synthesis Division — responsible for the development of new silane-based molecules. He is marketing manager, Americas, in Building Protection Products, a participating member of ICRI, ACI and NACE and a past sub-chair of ASTM Committee D01.47 “Concrete and Masonry Treatments.”