About us

For many years Siebert + Knipschild have been leaders in quality testing of plastics, especially in the area of water and soil protection (sewer rehabilitation, sealing systems). In Germany and abroad there is demand for our know-how as a test lab, inspection body and approved certification body. We provide tests, monitoring, opinions and expert reports for your project - all over the world. We conduct quality tests for 4500 samples a year. Numerous German and international public bodies and companies trust in us.

Our Passion for Quality - in 1 Minute


Our team of more than 20 engineers and technicians works in our head office near Hamburg and in two subsidiaries in North Rhine-Westphalia and Munich. The company is managed by Kay Siebert and Andreas Haacker. See more on the > Team page (German language)




The founder of the company was Rolf Siebert († 2010), who established CIPP quality control in Germany. After several decades of working as an engineer with the chemical company Hoechst he established the business in 1983.


In the young CIPP industry he defined rules and standards that are the basis for standards in Germany to this very day. He passed his know-how on to the next generation during his lifetime.

After the start as a one-man business the company developed dynamically, especially in the last decade. In 2006 Siebert merged with the company "Dr. Friedrich-Wilhelm Knipschild" in order to increase its business in the field of sealing systems. Since then the name has been Siebert + Knipschild GmbH Ingenieurbüro für Kunststofftechnik.