Green roofs in Mediterranean areas – Survey and maintenance planning

•Survey of 11 green roofs in-service conditions.•Evaluation of visual anomalies and associated causes.•Characterization of existing maintenance actions, type and frequency.•Evaluation of design options versus technical recommendations.•Maintenance planning proposal for green roofs in Mediterranean areas.

This paper addresses green roof maintenance in Mediterranean areas. A field survey is presented, describing building and roof systems of eleven case studies in Portugal, anomalies, causes and maintenance actions. The most affected system components were the vegetation layer, followed by the drainage system, substrate and paths. All inspected green roofs have regular maintenance, mainly concerning gardening operations, but a large dispersion in terms of frequency and type of maintenance actions was identified. The study confirmed that some design recommendations were not followed, especially the ones associated with singular points, accesses and safety measures. In-situ results were then used to propose a maintenance plan, structured for each system component, corresponding service life prediction and type of maintenance action. The inclusion of the real needs of in-service green roofs in Mediterranean climate, with specific requirements for irrigation and cleaning, led to a more accurate definition of the maintenance actions and their frequency. The responsible person for each maintenance action is indicated. That helps to minimize overall costs, pathology and risks.