Toolkit 14.
Renewal of Roof Space
Objectives
Roofs cover up to 32% of cities and built-up areas (Frazer, 2005) and represent a vast potential of currently unused space in urban centers. This potential should be more considered in the renewal of historical urban areas with high building coverage, such as Hongkong. Increased implementation of green roof technology is becoming standard practice in many cities to transform these urban rooftops into an environmental, ecological resource.
This toolkit is for the renewal of the existing roof spaces, which have not been fully utilized. It aims to:
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provide more high-quality outdoor spaces to enhance communication between residents
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provide more spaces that can receive enough sunlight in winter
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provide spaces that have better natural ventilation
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increase green space in the residential areas with insufficient ground greening.
Option 1. Roof Connection
The area of a single roof is very limited. Normally, it is smaller than the typical floor due to the occupancy of plant rooms. Therefore, the combination of multiple roof spaces can provide more area and include more functions. In addition, connecting multiple circulation cores can improve the efficiency of vertical circulation and the safety of fire evacuation.
The structure of the connecting part should:
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ensure an economical and reasonable span and width
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minimize the shading impact on the lower floors.
Option 2. Roof Communal Space
Because it has more sunlight and natural ventilation than the ground space, the roof space is more suitable as a communal space in some cases. For example, in the case study of Gonnghe Community, the roof receives more direct sunlight than the ground in midwinter, so it is more suitable for the gathering of the elderly and drying clothes. In the case study of the Kiu Wing Building in Hongkong, the roof can be the only communal space for the children in this building during the pandemic.
In the renewal of the existing roof and terrace, we propose to include at least a communal space that can be accessed by the residents freely. It can consist of:
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a dedicated playground for children
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a gathering space with seats for the elderly and the disabled
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shading devices that can provide shade in summer
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light-colored roof finish with high solar reflectivity
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railings with sufficient height and high perforation rate to ensure safety and natural ventilation.
Option 3. Roof Garden
In the case study of the Gonghe community, due to the lack of ground area, it is difficult to significantly increase the green area to meet the green coverage requirements in local standards. Roof garden can be a measure to improve the greening quantity and quality simultaneously. However, it needs to be adopted with more caution due to it will impact the loading of the whole building. The judgment will be made by the professionals based on:
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the structure type of the existing building
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the structural bearing capacity of the roof
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the current condition of the structure
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local climate data, especially precipitation.
Option 4. Roof Security
The regulation of access is necessary to ensure the security of this area. Due to the roof space being a communal space for residents, it is not a public area that allows people who do not live here to access it freely. In addition, since the roof is still a certain dangerous compared to the ground space, it should not allow children access without being accompanied by adults. The main measures can include:
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authentication measures in each staircase leading to the roof space
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access schedules for specified time periods
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24 hours CCTV.
Application of Toolkit 14.
This toolkit is examined in the following projects.
