For many years hydrophobisation agents have been the media of choice in order to protect masonry facades and building surfaces against moisture and destruction by weathering thereby leading to an increased lifetime.

In the beginning, hydrophobizing systems to be applied externally on the final constructed parts and outside structures were the first to successfully enter the market. However, although external hydrophobisation still accounts for the major share in the above mentioned applications, integral hydrophobisation enjoys increasing popularity and accpetance. In other words building protection is already taken into consideration during the actual construction phase. On the other hand dry mortars have gained importance in the construction industry over the past decades as they lead to increased productivity and improved quality. In order to improve product quality and to meet all kinds of specific requirements, dry mortars are modified with polymer binders and special powdery additives such as hydrophobizing agents (water repellents). At present metal salts of fatty acids are widely used as water repellents in dry mortars and represent the largest group of hydrophobizing additives. Particularly in regard to long term performance, metal salts of fatty acids exhibit some weaknesses. With this paper we would like to introduce newly developed powdery hydrophobizing additives. These additives are composed of silane/siloxane blends based on an inorganic carrier to be easily applied to drymix systems. As powdery water repellents they provide superior performance compared to metal salts of fatty acids and are easy to handle and dose. Due to their unique chemical design they provide outstanding water repellence and excellent beading along with true long term performance and sustainably protect buildings and architectural constructions.