When a car park becomes the highlight

Car park roof in Ħamrun, Malta 

Climbing the steps to the roof of the car park at the Misraħ is-Sebgħa ta' Ġunju 1919 Place in Ħamrun will bring you to a restful green paradise where the interplay of colour, form and light will help you forget the hustle and bustle of the surrounding city. Architects Doric Studio/Living Walls have created a spectacular feature from what was previously a desolate car park, therefore providing enormous value added for the residents within this community. Thanks to the ZinCo system build-up Roof Garden, this circular area with a diameter of just 25 metres offers a wide variety of perennials and shrubs, shaded and sunny spots, and different types of surface. This car park roof is truly a “must see” - even at night time.

Malta’s densely built-up cities are to become greener, offering improved quality of life. This task is part of the comprehensive portfolio of the Ministry for the Environment, Energy and Enterprise which oversees a number of officially appointed agencies. One of these is WasteServ, which set up the landscaping branch GreenServ as a new department specifically to address urban green projects in line with the Ministry’s objectives. The green roof in Ħamrun is the first of five greening projects launched by GreenServ, the others are located in Mosta, Qormi, Zabbar and Santa Venera. All projects are financed through the National Development and Social Fund. 

In architects and engineers Doric Studio/Living Walls, the public entity found a highly experienced and accomplished specialist who has been working together with ZinCo GmbH for many years now. In fact Doric Studio/Living Walls were also entrusted with the urban greening projects at Zabbar and Santa Venera following competitive tendering.

Endless creativity

The planners are only too aware that anything is possible on a roof where the ZinCo system build-up Roof Garden is used, as is the case on terra firma. When the new car park roof was built in Ħamrun, it was not a problem to design the structural aspect to accommodate the planned intensive green roof with its mature trees, and canopies made of steel and glass, in which, incidentally, solar collectors are integrated. 
The 485 m² circular roof consists of a steel structure with a concrete slab that is divided into sections for subsequent planting. The anchor points for the canopies are embedded in concrete at each point and a root-resistant synthetic waterproof membrane is installed across the entire roof area. It was at this point that the Maltese company, Derek Garden Centre, began their work of installing the green roof. The materials were easy to transport onto the roof as there is not only a stairway there but also a lift. The lift now ensures that the green roof is accessible to the numerous neighbours and visitors.

Green for go

The installation of the ZinCo system build-up Roof Garden began with the root-barrier WSB 100-PO and Protection Mat ISM 50. This synthetic fibre mat, highly resistant to mechanical stress and capable of storing water and nutrients, was the correct choice for the planned intensive green roof. The next layer was the drainage and water storage element Floradrain FD 40-E as the core element in this ZinCo system build-up. Water can be stored in the cells of this 40 mm high element made of thermoformed recycled polyethylene and excess water can be drained off to the roof outlets via an underlying channel system. The System Filter SF was next up. It prevents foreign matter from penetrating into the drainage layer from the overlying substrate. Suitably fitted with these elements, the total planting area of approx. 200 m² is perfectly equipped for all things green to thrive there.

Support for the trees

The next stage was to plant the 17 mature trees into these pre-prepared planting spaces. As it is essential that the trees are absolutely secured against wind pressure and wind suction on this panoramic rooftop location, ZinCo's Robafix tree anchoring system was used. It is easy to handle and doesn’t require roof penetration. The root balls were installed on 1 x 1 m grid elements made of recycled plastic, in which three anchor base plates made of aluminium were positioned to accurately match the diameter of the root ball. The tension belts were then fixed to these anchor points and wrapped around the root balls. This therefore prevents the contraction or extraction of the anchor points, enabling the root balls to be stable and permanently anchored. 

Once the trees were installed, the work continued with the substrate. Big Bags were lifted onto the roof to fill the 60 cm high plant areas: 57 m³ of mineral substrate base and 77 m³ of overlying substrate with additional top soil. Both types of substrate are volcanic in origin and come from the Mediterranean region.

Adapted to the climate

Adding to the trees that are characteristic of the Mediterranean climate – olive trees, holm oak, carob and the Judas tree – are native shrubs and perennials such as lavender, rosemary, laurel and myrtle. Even though the chosen plants are adapted to the local climate, an automated irrigation system using driplines was also installed. It comes equipped with rain and humidity sensors and has an option for dispensing fertiliser to the plants. The large reservoir beneath the car park is invaluable not only for storing rainwater but also for collecting excess irrigation water such that there is not water loss.

Interplay of material and light

The circular roof area between the four large planters is covered in wooden decking that runs towards a central gathering area in the middle of the roof. The IPE wood used originates in South America and is known for being long lasting and sustainable. 

Four large yellow parasols at the centre of the roof provide added shade but they also have integrated solar panels. This way, the electrical power generated feeds the LED lighting of the roof garden. These parasols with their rain water harvesting capabilities also sustain the WiFi system while the integrated mobile charging sockets provide added comfort to the visitors.

The power cables are concealed beneath the mounting for the 140 m² wooden decking that is used in the central area and the radiating pathways. A circular path with a surface area of 140 m² dressed in porphyry paving is installed all along the outer circumference of the green roof, enhancing further the design surface. 
It’s a wonderful place to take a stroll or have a break on the timber seats, either in the sun or in the shade beneath the parasols. During the day, there is a fascinating interplay of light as a result of the type of solar parasols used here. Even the centrally positioned white parasol with its small, round holes, lets the sun rays through. All of these elements - colours, forms and various lights - combine to create the special atmosphere on this roof – and at night time, you could go into raptures about it.

All round perfect

The greening project for the car park roof in Ħamrun was rounded off with a wonderful vertical green wall covering 20 m² and 120 m² of ground vegetation. The surrounding palm trees have grown so high that they directly encircle the roof garden. Now, nobody remembers what this car park actually looked like before its transformation. Today, it’s an appealing public green space that improves the air quality in the city, giving people a feeling of well-being and quality of life. May this humble space be a model for many future green roof projects!

Author: Fabian Kaiser, Head of International Sales, ZinCo GmbH

List of plants

Mature Trees: Olea Europea, Ceratonia Siliqua, Quercus ilex, Cercis siliquastrum

Shrubs: Lavandula agustifolia, Rosmarinus officinalis, Laurus nobilis, Sweet viburnum, Myrtus communis, Russelia equisetiformis, Tulbaghia violacea, Eugenia Etna Fire

Perennials: Santolina chamaecyparissus, Carissa strisciante, Westringia fruticosa mundi, Agapantus

Site board

Construction project: Car park roof Ħamrun, Ħamrun HMR 2150, Malta

Client: Government of Malta, Ministry for the Environment, Energy and Enterprise WasteServ Malta Ltd ECOHIVE Complex, Naxxar NXR 9030, Malta

Construction year: 2021/2022

Roof area: 485 m²  

Green roof build-up: ZinCo system build-up Roof Garden with Floradrain® FD 40-E and tree anchor system Robafix®

Architects/Landscape planners: Doric Studio/Living Walls, Birkirkara BKR, 9073 Malta

Steel Fabricators: E & L Enterprises Ltd., Birżebbuġa BBG 3000, Malta

Green roof contractors: Derek Garden Center, Qormi QRM 05, Malta

System supplier: ZinCo GmbH, 72622 Nürtingen, Germany

Substrate supplier: Europomice srl. 20124 Milano, Italy

Parasol & Benches: Mmcité a.s., 686 05 Uherské Hradiště, Czech Republic

Irrigation: Rainbird – I.V. Portello & Sons Ltd, Rabat RBT 1240, Malta

Lift: Groffe Elevator Services, Il-Gzira GZR 1401, Malta