Enhancing urban living: benefits of incorporating roof gardens

Roof gardens, also known as green roofs are increasing in popularity among urban areas as a sustainable and aesthetic design solution. Waterproofing and roof specialists, Viking Roofspec, discuss the advantages and process of implementing a green roof in your next project.

In a recent interview with Brendon Sutton, Sales and Marketing Manager at Viking Roofspec, ArchiPro explores the motivations behind roof gardens, the construction process, and how this green addition enhances the construction, sustainability and liveability of apartments.

Viking Roofspec is a leading provider of high-quality waterproofing and roofing materials. Protecting properties in New Zealand, the Pacific Islands, and even Antarctica for almost 50 years, the company’s roofing, decking, and below-ground waterproofing systems are designed to keep water out of homes and commercial buildings.

Increasing livability with a rooftop garden

Urban development often sacrifices green spaces, displacing flora and fauna; roof gardens help bring nature back to city living, attracting birds, bees and reinstating greenery. This is particularly important in medium and high-density living situations, such as apartments, offering residents an appealing escape from the concrete jungle. 

“The increase of high and medium density residential construction decreases outdoor living spaces. Including a roof garden in the apartment design utilises a building's ‘fifth wall’, creating a sanctuary amid an urban landscape, contributing significantly to the quality of life for apartment dwellers,” says Sutton. 

“Essentially, a green roof offers an area of relaxation, gardening or social activities — an ideal setting for escaping the hustle and bustle of city life, which is enticing for buyers and renters."

Managing stormwater with a green roof

Another primary motivation for installing roof gardens is to manage stormwater effectively, especially in metropolitan centres.  

“When concrete and asphalt dominate the landscape, these impermeable surfaces make it difficult for the stormwater system to cope with sudden deluges, leading to flooding. Roof gardens act as a natural solution, allowing rainwater to have a soft landing and gradually feed into the stormwater system, preventing flooding,” says Sutton.

“We work closely with all key stakeholders during the development of a complex or home, from design through to specification and installation. We provide advice and support to ensure a watertight, professional finish is achieved,” Sutton adds.

The soil in a roof garden system acts like a sponge, absorbing, delaying and gradually releasing stormwater. It also acts as a filter, purifying the water.

Green roof construction

Viking Roofspec specialises in roof gardens for low slope or flat roof buildings. Sutton emphasises the importance of a systematic approach to ensure the success and watertight integrity of the roof garden. 

“The process begins with an electronic leak detection system installed on the substrate – a crucial step to verify that the waterproofing membrane layer installed on top is 100 percent impermeable,” says Sutton.

“Layers are added meticulously, starting with the waterproofing membrane, followed by a root barrier to prevent plant roots from breaching critical layers. A drainage board with both drainage holes and water-holding cups and a moisture retention mat maintains soil dampness. The specific ratio of holes to cups creates a well-draining but moist environment for plants,” Sutton adds.

Roof garden maintenance

Sutton suggests selecting a roof garden-specific growth medium (not normal top soil), along with roof garden-friendly plants, such as aloes and grasses, to ensure the longevity and sustainability of the green space. Watering systems are usually installed for ease of maintenance, however this can be done manually.

Viking’s roof garden system is BRANZ-appraised, with components supplied and thoroughly tested by its overseas manufacturer. Sutton stresses the importance of sticking to the manufacturer's system to ensure peace of mind and uphold international warranties.

“Despite initial hesitations in the market, the architectural community has embraced roof gardens due to success stories along with the backing provided by reputable specialist suppliers,” remarks Sutton.

Increasing green footprint

This recent Auckland-based home extension would have taken up too much site area to achieve consent if it had a normal roof. As it would put too much pressure on the public storm-water system during heavy rain, potentially leading to surface flooding. The designer needed to think creatively to solve this potential issue and sought Viking Roofspec’s expertise.

The roof garden solution provided an easement with council, while also solving the stormwater problem and added insulation properties, requiring little maintenance and enhancing the extension’s unique design.

“The soil in a roof garden system acts like a sponge, absorbing, delaying and gradually releasing stormwater. It also acts as a filter, purifying the water,” says Sutton.

The 120-square-metre roof garden surface area takes the pressure off the public services by providing; in this instance, a 500mm deep absorbent catchment facility of roughly 60 cubic metres.

The Viking Roof Garden system drastically transformed this extension's roof and the home's overall aesthetic. The planted vegetation helps insulate and shade the property while reducing overall energy consumption and greenhouse gases.

Incorporating a roof garden into residential and commercial building design goes beyond aesthetics. It addresses practical concerns like stormwater management while providing a lush green sanctuary for residents. With Viking Roofspec’s systematic approach to construction and adherence to proven systems, roof gardens are transforming urban living, making apartments more comfortable, sustainable and visually appealing. As the trend gains momentum, Sutton expects the integration of green roofs into modern designs to become mainstream in urban development.