Proving the Efficiency of Post-construction Horizontal Water Stops Made with PU Injection Resins

At present, the efficiency and functionality of post-construction horizontal water stops is a very controversial topic. As a matter of fact, laboratory tests of standardized, homogenous test samples do not represent the actual conditions in old buildings appropriately. In practice, the brickwork concerned is usually inhomogeneous and frequently exposed to high stress levels caused by salts and cracked joints. The efficiency of a post-construction horizontal water stop made with PU injection resins has now been examined, proved and documented in an 80-year-old building in Tangermünde, Germany.

The engineering company W. Appel from Dessau recorded the damage thoroughly including the taking of brickwork samples for the analysis and determination of humidity and salt values in the laboratory. Furthermore, the distribution of stress caused by humidity was tested and evaluated graphically by means of microwave technology (Moist 200).

Brickwork stressed up to saturation humidity level with a large proportion of salts damaging the brickwork was found in the basement perimeter walls.

To repair these walls, a post-construction double-row horizontal water stop was installed in the 1st and 3rd row of bricks above the floor in May 2003. In so doing, the PU injection foam resin WEBAC_® 157 was used to fill cavities and the PU injection resin WEBAC_® 1404 was used for sealing purposes. 1 year after installing the water stops, their efficiency was checked by means of measurements. The same wall areas were examined as prior to the installation of the water stops. The result was that the degree of humidity penetration in the 40 cm and 53 cm thick brickwork could be reduced from 50 % and over 90 % to far less than 10 %.

This is the most spectacular proof of the efficiency of horizontal water stops under practical conditions. Thanks to the systematic use of PU injection resins in combination with PU injection foam resins, efficient water stops against capillary rising humidity can also be installed in water-saturated brickwork full of cavities and exposed to stress caused by salts.