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Hydromedia RoofTop Duo

A permeable concrete roof system with enhanced functionalities

May 2021
Gallery Hydromedia RoofTop Duo  1
Gallery Hydromedia RoofTop Duo  1


The solution offers the possibility of turning inaccessible roofs into attractive, modern and safe areas for recreation and fun. This transformation is possible thanks to combining Hydromedia pervious concrete technology and Nidaroof water storage capacity membrane. Thanks to this solution, investors can save on construction costs due to the downsizing of the rainfall drainage system. The habitants gain durable and safe areas to socialize, meet and relax. Cities reduce risks of peak rainfall floods and reduce the urban heat island effect.

  • /
Label Date May 31, 2021
By Holcim
From Switzerland
Maturity stage Initial market commercialization
Looking For Visibility

Implementation Stories

Hydromedia RoofTop Duo by Holcim
Implemented by Emmanuel d’Alzon’s School Complex in Saint-Medard-en-Jalles (France) in 2019

The City Hall of Saint-Medard-en-Jalles, adopted the Solution for its Emmanuel d’Alzon’s school complex in 2019. The client wanted to build a new school with a playground for students. However, the costs of acquiring land, getting a new design and a construction project were too high to furnish both the school and sports playground at the same time. An alternative was to build the playground on top of one of the buildings. Compared to the alternative mainstream solutions, the cost of ROOFTOP duo was about 4% cheaper per m2 for the total of 430 m2 surface.


Saved about 3,500 ⍬ on the construction cost and reduced the cost of maintenance


The environmental benefits

  • Can be adopted to any type of flat roof and can store from 26 to 494 L of rainfall per m2
  • Can be dimensioned for pedestrian and car traffic
  • Minimum 30 years of performance and reduced cost of maintenance
  • GHG potential reduction up to 17%
  • Captures up to 70% of rainfall
  • Using concrete with 20% less CO2 footprint and water retention membranes made of 60% recycled materials

The Financial benefits

  • 4% cheaper than a standard solution per m2
  • At least €3400 saved on construction and €1000/year on regular maintenance
  • 30 years of performance and reduced cost of maintenance

Activity Region

  • /


Spain, France,

  • Headquarters
  • Activity

Company Profile


Building progress for people and the planet

View company profile Solution website
Headquarters 6300 Zug, Switzerland

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The information set out above, is solely for the purposes of information and the Solar Impulse Foundation does not provide any guarantee as to its authenticity, completeness or accuracy. This information does not constitute investment advice or a recommendation to buy into, transact or to enter into any agreement with any of the parties or persons mentioned above. Potential investors or interested parties are solely responsible for their investment or business decisions and for performing any due diligence required by the circumstances. The innovator Holcim has asserted ownership of the intellectual property rights for images, videos, and content showcased above, affirming full and unrestricted usage rights, and has provided explicit permission for the Solar Impulse Foundation to publish such information designated as "public" in the application form.