Failure analysis of a spray polyurethane foam roofing system. (November 2020)

• Record Type: Journal Article
• Authors: Kalamees, Targo; Põldaru, Mattias; Ilomets, Simo; Klõšeiko, Paul; Kallavus, Urve; Rosenberg, Margit; Õiger, Karl
• Is Part Of: Journal of building engineering. Volume 32(2021)
• Publication Date: 2020-11
• Subjects: Spray polyurethane foam -- Polyurea roof -- Durability -- Hygrothermal performance -- Service life; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2020.101752
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: This study analyses the hygrothermal performance and service life of a spray polyurethane foam and polyurea roof in Estonian's cold and humid climate. Eight years after installation, the service life of the roof is over and it needs reconstruction. Field measurements included onsite temperature and humidity measurements and extensive surveying. The roof was opened from several locations and test samples were taken for laboratory tests. The material properties, which were measured after eight years, were not the same as declared by the manufacturer. Water leaked into the sprayed polyurethane foam insulation due to no protection during construction time. The UV degraded and the polyurea roofing had been mechanically damaged. Solar radiation quickly degraded the top surface of the in-situ sprayed polyurethane the foam insulation causing a weak connection between the foam layers. Water inside or below the foam evaporated on sunny days and water vapour pressure broke the adhesion between foam layers, which is considered the most realistic cause of separation for the SPF layers. Up to one meter in diameter or larger foam blisters were observed on the upper part of the insulation caused by high water vapour pressure from evaporated water. When using new structural solutions, more research and development is needed before construction. In addition to studying long term hygrothermal performance and service life, the ability to complete the construction should be tested and analysed. Highlights: Eight years after installation the service life of the large roof is over. Solar radiation quickly degraded the surface of the sprayed polyurethane foam. Water entered in the foam during construction because of rain and dew during night. The water inside or below the foam evaporated during sunny days. Internal pressure broke the adhesion of different foam layers.