The area surrounding the cultural centre ‘t Gasthoês in the Dutch village of Horst aan de Maas, now being renovated, is being redeveloped as a greenspace. This hard surfaced area is faced with the topical problems of heavy downpours, extreme drought and heat stress. The Rockflow infiltration buffer has been used in this area. The fully recyclable infiltration buffer ensures that local flooding on paved surfaces surrounding ‘t Gasthoês is reduced.


Rockflow buffers rainwater so it infiltrates the soil, thus maintaining groundwater levels. The climate atlas shows that the temperature at certain places in Horst aan de Maas is higher than elsewhere. When it rains heavily, the sewers are unable to cope with the rainwater. The Horst aan de Maas municipality has therefore decided to apply climate adaptation measures for the redesign of space around ‘t Gasthoês, creating a greener area that will reduce local flooding, heats up less rapidly, combats drying soils and maintains groundwater levels.


‘t Gasthoês used to belong to the Wonen Limburg housing association and is now owned by the Municipality of Horst aan de Maas. Marleen van Ulft is Senior Local Planner at Wonen Limburg. Keeping residential areas liveable and providing people with a pleasant working environment are part of her job. “Greenspace in residential areas is an important part of this”, she tells us. “The Municipality of Horst aan de Maas is increasingly emphasising climate adaptation. The sustainable transformation of the area surrounding ‘t Gasthoês, the Hof te Berkel, is a good example of this. Together, Wonen Limburg and the Municipality of Horst aan de Maas have started up this project to increase sustainability and green their existing properties and the infrastructure surrounding them. “To combat local flooding during the heaviest of downpours, the municipality sets standards for living environment, spatial planning, sustainability, maintenance and, of course, the related costs”, says Van Ulft.

The municipality’s main objective is to transform the area around ‘t Gasthoês into a green, open space, directly connected to the centre of the town. To achieve this, the existing car park has been completely redesigned. Van Ulft tells us that Wonen Limburg together with a large number of partners is involved in developing the planning of the public infra designs. This includes residents, entrepreneurs and construction partners.

This method of collaboration allows us to make well-considered decisions about increasing sustainability of the climate-proof urban environment.

Marleen van Ulft

Wonen Limburg
Senior local planner

Construction team

Wim Ramakers is project leader at the infra company BLM Wegenbouw in Wessem. “We are working on this project as a construction team”, says Ramakers. The construction team consists of the municipality as the customer, main contractor BLM Wegenbouw and Kragten Consultants, who supported the municipality during the initial design phase of the redevelopment of ‘t Gasthoês area, in which the Rockflow smart water management system has been used as a total solution. Rockflow regularly participated in this construction team to contribute their ideas about a total solution. “The area will have a varied, sustainable character. Thereby improving both the general and living environment in the hard surfacing of the urban area.” The car park will remain intact and must remain accessible.

The rainwater will be captured by soil infiltration, as far as possible. “All drains in the hard surfacing will be connected to a separate rainwater sewer leading to the Rockflow infiltration buffer. During extreme downpours, the buffers will absorb the rainwater and then release it gradually to the soil. “This will prevent local flooding and drying out of the soil.” Roof runoff from ‘t Gasthoês will also be captured and diverted to a permavoid system with stone wool ensuring the transport of water to the planted area. This system consists of underground water buffers underneath the greenspaces that create a capillary action, ensuring the water level for the vegetation is maintained. “In this project we are testing whether the Rockflow system can replicate the tried-and-tested permavoid system”, says Ramakers.

Climate improvement

Joop Schagen is Local Development and Citizen Participation Adviser at Kragten in Herten. “Local flooding during heavy rainfall and major heating of urban areas in the summer are currently hot topics”, says Schagen. “Municipalities are increasingly recognising the problems caused by hard surfacing in the urban environment.” The fact that the Netherlands is once again being confronted by a period of drought is strongly influencing this. “Less paving and more greenspaces in towns results in less local flooding and more cooling in the summer.” Schagen explains that for greening the ‘t Gasthoês area, the Rockflow water management system combined with water permeable ZOAK paving and the proven permavoid system is the perfect solution for capturing water and retaining it in the soil.

The infiltration buffer is a practical, sustainable solution for the current water management problems increasingly faced by municipalities. It is highly permeable with rapid absorption properties and can absorb 95% of its own volume in water.

Joop Schagen


“This permavoid system creates optimum growing conditions for the plants and trees that will ultimately have a strong contribution to improving the area’s environment”, says Schagen.

Ralf Vaessen is director of the gardening company Herman Vaessen in Maasbree. He is involved in the ‘t Gasthoês project as a specialist in innovative greening of hard surfacing in the urban landscape. “The intention is for this area to be capable of buffering around 400 cubic metres of water, infiltrating it into the ground.” Vaessen explains that collaboration as a construction team with the other partners is the driving force behind the project. “During the preparatory process, these partners had ample opportunity to share and apply their expert knowledge and expertise.” Vaessen installed the equipment that monitors and regulates the water content using sensors and moisture monitoring. In the area around ‘t Gasthoês, various parking spaces have been repaved with TileSystems ZOAK paving. These are made from waste from ceramic tile manufacture and can rapidly absorb rainfall. “An interesting feature of these tiles is that they not only rapidly absorb, buffer and allow infiltration of the water, allowing it to drain to the underground Rockflow infiltration buffer, but they can also allow water to evaporate after a heavy summer shower. During hot summer weather, this has a cooling effect”, says Vaessen.

Trial areas

Linda de Vries, Business Developer at Rockflow, works on applications for stone wool in water management systems with a focus on urban green and climate adaptation in the urban environment, making use of circular materials. De Vries explains that the ‘t Gasthoês project is progressing in a virtually unique way because an innovative construction team has been working on it. “It is particularly interesting to be a part of this and to experience how we can collaborate to implement all the customer’s wishes”, she states.

Expertise is shared to produce a joint design for the green space in this area in which water is retained and recycled.

Linda de Vries

Business Developer

This type of collaboration is virtually unique in this type of infra project. De Vries believes that it will become more common in the future for implementing partners to work jointly on this type of project finding the correct solutions for problems related to drying out and water management in the public space. She explains that in this project, planting areas were laid out containing a substrate mixed with loose stone wool and capillary stone wool elements to test how water can be retained close to the surface. In contrast, to allow excess water to infiltrate as rapidly as possible, water from small showers of rain is retained to prevent drying out. This substrate has a strong absorption capacity and its capillary action ensures that water is drawn to the surface from a buffer so that the soil remains moist and the plants do not dry out. “Water is retained so plants can survive through dry periods. This project offers a superb opportunity, particularly in this period of drought, to carry out these tests”, says De Vries.

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Roy Janssen

Business Unit Director,