A look at the rooftop park of The Three Horseshoe Farms 

A large rooftop park of more than 3,500 square meters. Many beautiful plantings, including birch, pine and a floral seed mixture. A hilly surface provided with a thick layer of substrate, allowing the plants to grow finely. And all this on the roof of a parking garage: project consultant Pieter Bos of Van der Tol BV takes us for a look at the garden.

Since 1945, Van der Tol has grown into a green business with three branches in the Randstad region with over 130 employees. Their mission is loud and clear: "to make the city greener, healthier and more livable. Bos: "We do this by promoting biodiversity, effective use and reuse of (rain) water, combating urban warming and improving the indoor climate: all within the framework of our EcoCity vision. Part of the projects we realize in this regard is the creation of roof gardens."

Almost three years ago, Bos stepped in to this project from Van der Tol. "In the beginning, the biggest challenge was to show the municipality of Breda the advantages and possibilities of a roof garden. After all, they will be the end user." A delegation from the municipality came to the Randstad to take a look. "Here we showed them a similar project in progress. But also a similar project that we realized several years ago, including trees and all the trimmings. That way the municipality immediately had a clear picture of a roof garden project: what's it like? And what about the maintenance? The result: the municipality also became enthusiastic about the plans."

The courtyard garden was designed by design firm Burobol. Van der Tol then provided advice: how can the design be realized? This involved a number of challenges, Bos says: "It involves a parking basement with two levels. In between is a ramp and a flat roof with no slope. So we had to think carefully about the drainage. It took a lot of calculating and measuring to see which drainage layer to use. In the end, a drain was dug next to the eaves, so we prevent water flooding."

That this indoor garden is being built on top of a parking garage proves that a roof garden doesn't always have to be on top of a building. "And then again, it's a roof garden with a hilly landscape," Bos says. "With substrates for the plants and Styrofoam (EPS), we have created a landscape that at first glance you don't see that you are standing on a roof garden. This way people will soon be able to enjoy this beautiful coulisse landscape."

The rooftop park contains many fun elements. Bos: "For example, there is a water element made of natural stone. This element is a nod to the beer brewery that used to stand here. So you see a beer tap and beer bottles, through which the water flows down. A nice, lively element in the middle of the garden."

A challenging requirement was that a fire truck could drive over the pavement. "We had to do a lot of math for that, because you can't just put all that weight on a roof. We looked carefully at how to get the lightest possible construction, yet strong enough. That's why we used glass foam as the foundation material with a small finishing layer of lava for paving. That also immediately helps with drainage, because it doesn't hold as much water. Moreover, the asphalting was done with small machines to distribute the weight nicely."

The roof garden is sown with a flowery seed mixture. "That makes for a colorful whole," Bos emphasizes. "We also planted 12 trees that provide height and variety. The trees have been placed on the supporting columns of the parking garage with a layer of substrate. This is because those columns can bear the weight well."

"There is also a terrace with a cozy restaurant. Two play elements were also built for the neighborhood children. Of course, the poles couldn't go deep into the ground, so special foundations were made for that. This way the children can play nicely and the whole neighborhood can enjoy peace and greenery."