Green Roofing: A multi-faceted approach

Germany’s cities are true heat islands, especially in summer. A temperature difference of seven to nine degrees Celsius is quickly reached between urban areas and their surroundings. In a measurement conducted by “Brisant,” a temperature of 26 degrees Celsius was detected in the center of Leipzig in July 2022, while it was only 18 degrees Celsius on a country lane just seven kilometers away. One reason for this phenomenon is the high level of sealing in cities. Another reason is the obstruction of air circulation due to the density of buildings.

Absorb, Insulate, Filter – The Green Roof as a Natural Shield

Additional green spaces can significantly reduce the urban heat effect, according to a study by the German Federal Environment Agency in 2022. Green roofs are a particularly popular trend and their area has more than doubled in Germany since 2008. This provides better air quality, an improved micro (and even indoor) climate, and contributes significantly to temperature insulation. Green roofs also reduce the risk of flooding during heavy rainfall events, as the various layers partially absorb rainwater.

The roof of Nivy Mall in Bratislava features a 12,000 m² terrace that provides a variety of sports, work and leisure opportunities throughout the year and is directly connected to a lively catering and market area.

The right greenery for every roof

Basically, all green roofs follow a similar structure: A root-resistant seal is applied directly to the roof structure. This is followed by the storage and drainage layer, which is usually covered by a filter fleece. On top of this are substrates and finally the vegetation. The load-bearing capacity of the roof structure determines what vegetation can be planted on the roof. In general, there are two different types:

Extensive green roofing: mostly consists of plant communities of sedum, grasses and herbs, which require little maintenance. The layer height of the substrate here is up to 15 cm, which results in a relatively low weight load. This makes it particularly suitable for the subsequent greening of existing roofs.

33 Central in London/UK: A blooming heaven with a 1,300 m² rooftop garden planted with over 40 different wild plants and native flowers, offering breathtaking views of the city.

Intensive green roofing: allows the complete spectrum of landscaping, including lawns, perennials, fruits and vegetables, trees, but also pavements, terraces or recreational areas for office users, for example, depending on the statics of the roof. The layer height of the substrate is up to 100 cm, which results in a correspondingly higher weight load. Regardless of any trees and other superstructures that provide additional weight.

Our project Forest in Warsaw provides the perfect oasis in the midst of an everyday office life with 2,100 m² of greenery, 4,500 m² of patio space, and an impressive variety of 200 trees and shrubs.

Leading by example

Around ten percent of all roofs in Germany are green. This puts Germany in an excellent position globally. With regard to the advancing climate change and improved user experience, we at HB Reavis also embrace green roofs and/or rooftop terraces, opting for intensive greening rather than just extensive solutions: at DSTRCT.Berlin, for example, with tree plantings.

DSTRCT.Berlin features a panoramic roof terrace of approximately 1,200 m² as well as courtyards with open spaces totaling more than 1,400 m².

HB Reavis Germany GmbH

Matthias Goßmann

Head of Leasing

+49 30 586 199 100



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