Building diseases: Interior flooring made of “terrazzo” prefabricated cement mortar tiles: Three case studies

• Author proposes a method to find the causes of an anomaly based on ten questions listed.
• When examining reasons for anomalies it is possible to differentiate direct and indirect causes.
• Even extensively used techniques can be affected by major anomalies.

In Spain, and in the Mediterranean area in general, there is a long tradition of using “terrazzo”, prefabricated cement mortar tiles with a polished upper surface as interior flooring in public and private buildings. This flooring technique provides a surface that is mechanically strong, hard and stable in the long-term.Terrazzo flooring has an appreciated appearance of continuity if installed correctly. In addition, the resulting paving can be polished periodically (every 5 years), which makes it highly prized because it can be made to look new again. Today, it is probably the most common interior flooring technique in Spanish buildings. Everyone, including manufacturers, technicians, workers and users, recognize that it is reliable.However, 10 years ago several incidents occurred in which a notable surface area of terrazzo was affected. The incidents raised the alarm about this interior flooring technique. Such occasional anomalies, as well as changes in consumer tastes, have questioned the supremacy of this technique in the flooring product market.This paper analyses in depth the causes of three such incidents that occurred between 1999 and 2001. The author acted as an external expert consultant in these cases. The first building was a public facility for a university research organization. The anomaly appeared during the construction phase, prior to occupation of the building. The second and third buildings are multifamily housing buildings situated in the same district. The anomaly was declared when people first lived in the building.The conclusions indicate that even extensively used techniques that are currently in the mainstream market can be affected by major anomalies if:–Rigorous technical quality control is not applied at the building site.–Last minute changes on-site are not authorized by those with previous experience.