Increased risk for damages from the dry-rot fungus Serpula lacrymans on buildings in a changing climate

Abstract

Weather-based damages in housing insurance correspond to 23 % of all insurance claims in Sweden and include damages from fungi. Some fungi could cause health risks to the tenants, while others can cause rapid structural failure for the building itself, like the dry-rot fungus Serpula lacrymans.

The study aims to analyse a possible connection between the increased rate of insurance claims related to S. lacrymans fungi and climate change. This study uses historical data of 2446 damaged properties from insurance companies and current and future climate data. In addition, eight geographical areas within Sweden with 567 damaged properties were analysed in relation to changes in outdoor temperature over a decade. Finally, a full onsite inspection of 20 infected properties by S. lacrymans fungi was conducted to evaluate common conditions for fungi infections.

The results of this study showed that the S. lacrymans fungus is expected to spread to the northern parts of Sweden even in areas where it could not exist before, while the rate of infected buildings in the southern part of Sweden might decline but not drop to zero. Wooden buildings older constructed before 1980 with chimneys and self-ventilation are at higher risk of infection. Economic implications are significant, with high repair costs rendering some buildings economically unviable, particularly in rural areas. Insurance reimbursement is typically limited to market value loss, indicating location, design, and maintenance status as crucial factors. The results may raise a concern for insurance companies and property owners, especially related to locations in the sparse parts of North of Sweden.