Crystalline coating is a technology which is designed primarily for an additional protection of underground concrete parts of buildings against moisture and subsurface water. The compound for a surface-applied crystalline coat or sprayed layer (in a thickness of 1–1.5 mm) is created by mixing crystalline powder material with water. The dry crystalline material (powder), which underlies the crystalline coating, consists of Portland cement, specially treated quartz sand, and a compound of “active chemicals.” The chemical composition of active chemicals in the crystalline material is kept confidential by all producers. The crystalline material’s waterproofing effect in concrete is achieved by the reaction of various chemical components contained in the solution when combined within the concrete matrix. The process only works when the porous system of concrete reaches a sufficient level of moisture and has open character, which is typical for the concrete of lower grades. Sufficient transport properties of the concrete are probably the necessary prerequisite for the crystalline agent efficiency. Therefore, perfect moistening of the coated surface is very important. In the case of a shortage of moisture inside the concrete structure, the crystalline coating’s components lie dormant.