Sustainable water management for trees on a parking garage roof

How do you keep greenery thriving on the roof of a parking garage? This requires a well-designed, lightweight, and maintenance-free water management system.

Capillary System for tree water management at Museumpark

Rotterdam welcomes a new iconic building: Depot Boijmans van Beuningen. This is the world’s first museum depot where the entire collection is on display. The arrival of the depot has prompted the city of Rotterdam to green the area around Museumpark.

Water retention on parking garage roof

In the first phase, 17 of a total of 75 trees were planted on the forecourt of the depot. Forty-three trees cannot be planted in the ground because the building’s foundation prevents it or because they are located on the roof of the adjacent parking garage and water retention area. A water management system is needed here to create a sustainable growing environment.

Challenge us

Contractor GKB challenged Joosten Ecodak to design a system that can easily irrigate the trees. The successfully proven Joosten AquaMulti Box Capillary System (JACS) was chosen.

Joosten AquaMulti Box Capillary System

JACS is the solution for transporting water from the water reservoir to an overlying layer. The system is based on a 150 mm high field, consisting of AquaMulti Box buffer crates wrapped in VLU WSC geotextile.
By placing the VLU WSC geotextile vertically at pre-calculated points, water is drawn up from the buffer crates and passed on to the fleece above the crates. The water is then quickly and evenly distributed over the horizontal layer above, usually a capillary substrate. This way, vegetation can draw from the stored water in the reservoir even during dry periods.

Convincing proof

To convince the municipality of Rotterdam of this innovative new system, a practical demonstration day was organized by GKB. Employees from the municipality and supplier Boomkwekerij Ebben were given explanations about the system’s operation and the properties of the materials used by Joosten Ecodak. GKB addressed the practical aspects of the project regarding execution and scheduling of the work.