Maintenance Guidelines of Green Roof in Condominium: A Case Study of Q Chitlom–Petchburi and Ideo Phahonyothin–Jatujak

Abstract

Green areas are essential for health and quality of life of urban residents. According to regulations, condominiums must provide at least 1 square meter of green area per 1 person.   However, due to limited space, green roof in roof garden must often be constructed to meet the minimum green area requirement. Roof gardens and green roofs, however, require different maintenance compared to ground – level green areas. The aim of this research is to study the maintenance for green roofs and identify the causes of common issues and their potential solutions. In this study, Q Chitlom – Petchburi (QCP) and Ideo Phahonyothin – Jatujak (IPJ) are selected as case studies. These two projects consist of green roofs around 50% of their total green areas. The research methods involve photographing the case studies and interviewing designers, gardeners, and experts to explore the problems and solutions related to the maintenance of green roofs in condominiums.             

The findings indicate that, first green roofs consist of various elements including trees, shrubs, groundcover, grass, soil, drainage systems, and waterproofing. Second, the two case studies follow similar maintenance practices, with two individuals responsible for all green spaces, including the green roofs, for at least 8 hours per day. Pruning and fertilizing occur at least twice a month. Third, the advantages of these green roofs include the healthy condition of most trees, shrubs, groundcover, and grass, which is a result of high-quality maintenance. However, some trees did not survive and the replacement with specimens of the same size could not be done. Shrubs and groundcover struggled due to insufficient sunlight, and some grass areas failed because they were frequently walked or run on. Additionally, there were some instances of leakage. Finally, proper green roof maintenance should consider sunlight, irrigation, drainage, soil quality, appropriate use of the space, and the positioning of the green area. Maintenance practices for green roof components should vary, as follows: 1) Trees should be pruned and fertilized every 3-6 months and must be able to withstand high-altitude conditions, with a maximum height of 3 meters. 2) Shrubs and groundcover should be pruned and fertilized 1-2 times per month. They should also tolerate high building conditions and should not involve a wide variety of plant types. The chosen plant should be easily planted by stem cutting method. 3) Grass should be planted in areas that receive at least 6 hours of sunlight per day and should be located in spaces that avoid heavy foot traffic. (4) Other components, especially drainage systems, should be tested at least every 3 months.