This injection method, also known as gel coating or screening, involves the coating of the underground part of the building in a layer of waterproof material, or screen. The layer is created outside the wall or in between two structures. This method allows saving money, because it does not require exposing the whole underground part of the building and the whole cross-section of the wall is protected against moisture. The main precondition for this method is testing the surrounding soil, which will be injected with the waterproofing substance. Generally, the materials used with this technology are from the group of acrylate gels, also known as hydrogels. These gels come in a wide variety of types with different properties, such as elasticity, adhesion, water resistance, shrinking, expanding and reaction time. Since these gels are always in contact with the ground and rain water, their physiological neutrality is also very important.