Protection for Generations to Come - Wacker Chemie AG

Protection for Generations to Come


The aim of hydrophobic impregnation is to permanently reduce moisture absorption in the exterior or in other parts of a building, while retaining the ability of the building material to breathe. After application, the active ingredient of the water-repellent agent penetrates the surface of the structure and reacts with the silicate matrix of the building material, rendering its capillaries and pores water repellent. The formation of a hydrophobic zone reduces the surface tension of the building material to such an extent that water and the harmful substances dissolved in it can no longer penetrate in liquid form. The basic prerequisite is the selection of a suitable combination of active agents in terms of molecular size, mobility, reactivity and resistance to chemical and physical influences. Choosing the right water-repellent agent is a must for minimizing water absorption, allowing the active agent to penetrate as deeply as possible, and having it form a lasting bond with the building material matrix.

Renovation also included typical repairs to the foundation: workers from Burghausen’s department of public works removed the old paint with a high-pressure cleaner and filled cracks with mortar. A few days after removing the paint, workers repainted the entire building exterior with a silicone resin emulsion paint made by Sto – and based on SILRES® BS silicone resin from WACKER – giving the chapel’s render an efficient coating that is water repellent yet breathable.

“Silicone resins have a high affinity for mineral-based surfaces, which makes hydrophobicity an integral part of the paints – and that gives them a highly effective, lasting degree of protection,” explains Albert Hausberger, an applications engineer at WACKER who specializes in silicone resin emulsion paints.

Water Vapor Can Diffuse

Dr. Hartmut Ackermann in front of the Bergerhof chapel: this tiny place of worship also gives WACKER’s building protection experts an opportunity to demonstrate their high-performance products.

European standard EN 1062-1 categorizes silicone resin emulsion paints in the best possible class with respect to their permeability to water and water vapor. The unique properties of SILRES® BS silicone resins ensure that water from outside will bead on the building’s exterior, while still allowing evaporating water to diffuse out of the wall in the form of steam – a characteristic that prevents damage from accumulated moisture below the coating.

As a final measure, WACKER building protection experts also recommended hydrophobic impregnation of the chapel interior using SILRES® BS 290, a mixture of silanes and siloxane that has been diluted with organic solvents. A high-quality, general-purpose primer and water-repellent agent for mineral-based – and even highly alkaline – substrates, SILRES® BS 290 results in a lasting reduction in the amount of moisture that building materials absorb.

Thanks to this project, the interior, exterior and masonry of the Bergerhof chapel are now equally well protected from moisture, ensuring that subsequent generations will be able to enjoy the colorful fresco of Italian painter Nunzio Di Placido in all of its splendor.