Over the years, buildings suffer considerable physical and chemical damage caused by water penetrating into building materials. However, thanks to silicones, water repellent products protect these materials from such damage.
Silicone water repellents are silicone resins that contain crosslinkable side chains. Their chemical structure enables them to bond the substrate and to repel water without impairing the substrate's ability to breathe.
Their ability to "wet" the surface, capillaries and pores of the building material is a benefit of their structure at the molecular level. In a sense, their organic groups (R-) act like the bristles of a "molecular brush", preventing the building from getting wet, not by sealing the pores but rather by holding the water at bay. Since the pores and capillaries do not become clogged, the material stays permeable to water vapour.
Silicone water repellents are used for factory impregnation of roof tiles, ceramic tiles, cellular concrete sections, sand-lime bricks, plaster and plasterboard slabs, and for the protection and renovation of concrete and reinforced concrete. They are the main ingredients of injection agents for combating rising damp and are additives for upgrading cement and lime based mixtures of building materials.
Adding water repellent emulsions to organo-silicate paints, limewashes and lime-cement plasters has improved their performance and opened up the way for silicone resin emulsion paints and binders for facades.