Lighter, better more efficient green roofs

Lighter, better more efficient green roofs

Green roofs are a trend on the rise. In South Africa, the city of Durban is at the forefront of this phenomenon. While Germany, is listed as having the most green roofs in the world.

BERA Urbanscape has created a green roof product that helps landscape architect, engineers and construction companies with installing roof top gardens. In 2018, BERA BV helped install a 600m2 roof garden in Zambia.

Benefits of green roofs in cities

Green roofs benefit cities by reducing radiation on roof tops and combating the urban heat island effect. Green roofs also increase the biodiversity of a city offering a green refuge for urban wildlife like birds.

The foliage on the roof reduces noise pollution as well as provides a green escape for people in high rise offices or apartment buildings.

The challenges of installing a roof garden

Despite being aesthetically pleasing and eco-friendly, green roofs, pose some challenges for engineers. Firstly, the waterproofing has to be done properly, it’s a mission to get soil onto a skyrise, digging it all up again to fix waterproofing is costly.

Think about it, soil, water and large trees (depending on the roof) are heavy so you need to be wary of excess weight on the structure.

Wind can be a bit of challenge in skyrises too as it uproots plants that have not had a chance to get their roots deep enough into the soil. In windy cities like Cape Town, South Africa, recently-planted roof top vegetation is blown out of their beds.

Shadowlands pre-grown succulent blankets using BERA Urbanscape.

With the challenges of installing a green roof in mind BERA BV has developed instant green roof product using BERA Urbanscape Green Roll.

Shadowlands has developed an instant pre-grown blanket. Basically, what this means is the plants are already planted and have established roots in the blanket so they are less likely to blow away.

The entire blanket with plants is placed on the roof reducing the turnaround time on a job.

BERA Urbanscape Green Roof System

It all starts with Root Membrane. Root Membrane is a thick micron plastic, that allows for better waterproofing, it also creates space for drainage, increasing the longevity of the bore drains and waterproofing. It also prevents drains from blocking.

Then Drainage Universal is added that allows for 30 tons per metres squared of weight. Above that is the two-centimetre-thick Green Roll that has a holding capacity of 17 litre per metre squared. Green Roll reduces water runoff and provides consistent water to plants thus reducing the need for thicker soils.

The Green Rolls ability to store water allows it to act as a retention aid while not damming as its composition is 80% air volume. When saturated, the weight of 100ml of soil is between 60 and 70 kilograms per metre squared.

The Urbanscape Green Roll also reduces watering by up to 50% as well as fertilising rates as the spun down rock is high in minerals, stimulating root growth. BERA products are manufactured in the Czech Republic and has Cradle-to-Cradle certification.