Sempergreen and Knauf Insulation launch Detention Roof - a new and innovative green roof concept

Climate change is causing a tremendous increase of the number of stormwater events. As a result, urban areas are faced with major damage due to flooding. In collaboration with other international partners, Sempergreen and Knauf Insulation has developed a new and innovative green roof concept called Detention Roof. The Detention Roof makes an important contribution to water issues within urban areas.

The effectiveness of the Detention Roof has been extensively tested and proves that excess rainwater can be temporarily detained on the roof during heavy rainfall and runoff can be delayed. This allows the Detention Roof to comply with the governmental water policies. On the newly launched website detentionroof.com a project-specific water calculation can be requested.

Collecting rainwater where it falls first

The Detention Roof is an important tool in the fight against the negative effects of climate change. This climate-adaptive roof solution can be used in addition to existing underground solutions, such as bioswales, infiltration crates or a rainwater tank. Investing in above-ground and thus visible solutions not only provides more awareness, but also offers additional benefits. Green roofs contribute to a reduction in the ambient temperature, they have a heat-regulating effect in the building, stimulate biodiversity and extend the life of the roofing. Moreover, a green roof provides financial added value to a building.

Detention Roof and governmental water policies

The Detention Roof is a storm water tool that makes optimal use of the available space on a project. With the help of a Detention Roof, the sewer system is relieved during heavy rainfall or multi-day storms and flooding is prevented. Thanks to these unique properties a project can comply with the requirements and wishes of the (local) government and water board by applying a Detention Roof.

Green Roof Diagnostics research laboratory in the United States

Tested and proven

Various international partners, including Sempergreen and Knauf Insulation are at the basis of the development of the Detention Roof concept. In collaboration with independent researchers, the partners have conducted research into the optimal green roof structure with regard to the delayed drainage of rainwater in the Green Roof Diagnostics research laboratory in the United States for many years. By using a simulator, heavy rain showers were simulated in the laboratory to measure the performance of dozens of green roof structures in a water-saturated state. The innovative Detention Roof concept was created from these test results.

Four construction layers, each with a unique effect

The Detention Roof is a lightweight green roof system and consists of four layers. Each layer has its own unique effect, which ensures optimum results. Thanks to its construction, the Detention Roof is able to temporarily detain the rainwater and delay runoff, even when fully saturated. The saturated weight of the Detention Roof is approx. 90 kg/m². The Detention Roof is easy to install and can be applied on roof slopes from 0 to 5 degrees.

The construction of a Detention Roof

Project-specific water calculation

A new website has been developed for the launch of the Detention Roof: detentionroof.com. On this website, architects, contractors, project developers or governments can request a project-specific water calculation for projects of 200 m² or more. The outcome of this water calculation will demonstrate exactly what a Detention Roof can yield within a project.