Sea breeze on the Lower Rhine

Reference: Graduation house Kevelaer

Reference: Graduation house Kevelaer
The pilgrimage city of Kevelaer

A sea breeze at the Lower Rhine

Being a place of pilgrimage, Kevelaer has always been welcoming to visitors. While in the past, it was mainly tour groups coming to the Lower Rhine, today it is predominantly individual tourists visiting the Chapel of Grace and the effigy of the Virgin Mary. As early as 1992, during drilling works, a brine spring was discovered at the Lower Rhine pilgrimage site. But it was not until two decades later that the city came up with a reasonable concept for using the salty water from the depths. The aim was to combine traditional pilgrimage with ever changing travel patterns and classic spa treatment.

Architecture to impress

Inspired by the scallop

The pilgrimage and brine park “St. Jakob” was set up according to the slogan “Healthy in body and mind”. The central core is a new graduation house designed by architect Peter Grund from Kassel. Its footprint and roof layout resemble the shell of a scallop. “With Kevelaer being a place of pilgrimage, this is most certainly not a mere coincidence," explains Peter Grund, “ultimately, however, it is meant to be a sustainable unique selling point in times of ongoing architectural cannibalisation.”

Adapted to a favourable climate

Based on “old knowledge”

Essentially, the graduation house consists of the brine collector, the thorned wooden structure, the roofs, two wooden towers and the brine technology. The brine collector, made of water-impermeable and salt-resistant concrete, in combination with corresponding strip footing provides a stable foundation for the wooden structure. The latter is composed of several main and secondary frameworks transferring the load to the strip footing with wooden beams. Cut-to-size infills of bundled blackthorn are placed between, in front of and behind the frames. A roof consisting of five individual sloping-ridge saddle roofs above the rafters provides protection from rainwater, i.e. fresh water. This is also where the maintenance aisle for the sprinkler system is located. It can be accessed via the northern tower. The eastern tower houses the technical facilities, including pumps and sumps as well as fresh water and power supply equipment. A multi-functional “drift pavilion” is located on the eastern side of the graduation house, preventing the salt-enriched air being blown away by westerly and south-westerly winds, while at the same time promoting a humid and cool brine microclimate in the interior of the graduation house.

On the western side, the brine trickles down over the thorns of the blackthorn onto five plane surfaces. Solar radiation and warm air provide additional turbulence, creating a mild and humid climate.

Microclimatic zones like at the sea

Like a walk at the sea

The shape and the design of the graduation house allow for many “microclimatic zones like at the sea” in a very small space. For a quiet experience, the 12-meter-high graduation house is situated in a park with numerous resting areas. In addition to rest and relaxation, the brine park also offers Kneipp facilities, a barefoot park, a Bible Garden, as well as two boules pitches and a beach volleyball court for the pilgrims and visitors to the city.

A challenge for building material

Tough, in any wind and weather

While the salt-enriched air is good for the visitors’ respiratory system, it requires far-sighted use of materials. After all, despite being located at the Lower Rhine, the building materials must be resistant to seawater. Usually, wood is quite resistant to salty air, the high air salinity makes it even more durable. The concrete brine collector has an additional coating to provide sufficient resistance. Special care was also taken to ensure reliable covering of the reinforcing steel. The five attached saddle roof areas are covered with a seawater-resistant synthetic roofing and waterproofing membrane.

Saltwater resistant waterproofing

A special highlight

Peter Grund came across this waterproofing system while reconstructing a graduation house in Remscheid-Lennep. The task was to keep the existing wooden brine collectors and to retrofit a waterproofing for environmental reasons. While searching for appropriate materials, the architect, who is specialized in graduation towers, found what he was looking for at the flat roof specialist alwitra GmbH: the long-term seawater resistant EVALON® roofing and waterproofing membrane.

Ideal for mechanical fastening

Best conditions

The waterproofing of the five saddle roofs on the graduation house was carried out by the roofing company Grote GmbH & Co. KG from Weeze. As the roofing and waterproofing membranes were to be mechanically fastened on the roof, the homogeneous reinforced EVA waterproofing membrane has proved to be the ideal membrane for the planned waterproofing. Even though the roof with its cold roof design did not have a particularly complex structure, due attention needed to be paid to the salty air conditions. First, the roofers applied a fleece on top of the wooden substrate serving as a fire-retarding layer. After that, they installed the EVALON® dual waterproofing. The membranes, fixed in the seam area with stainless steel anchor bolts, were then homogeneously welded in the overlap area with a hand-held welder. Moreover, at the roof ridges, the roofers attached correspondingly bent coated stainless-steel sheets. Continuous flashing tape made for an accurate ridge design, at the same time providing protection against wind uplift.


Customised roof edge trim profile

From the roof edge experts

The roofers also applied the high-quality coated stainless-steel sheet from alwitra at the roof edges. As agreed with the architect, it was bent into shape to form an individual roof edge profile. In addition, the roofers cut the leg to be fixed to the roof surface in segments to accommodate the curvature of the verge. The roofers also formed elements to connect adjacent bent coated metal sheet profiles. In contrast to the slate grey roof surfaces, the roof edge trim profiles are in light grey, as the architect wished to accentuate the exceptional shape of the roof resembling a shell. Apart from the five saddle roofs, the roofers installed the EVALON dual roofing and waterproofing membrane also on the roofs of the two towers and the “drift pavilion”.

A gentle sea breeze at the Lower Rhine

Sea air in Kevelaer

Even though the pilgrimage and brine Park officially opened only in 2020, the special microclimate of the unusually shaped graduation house in Kevelaer could already be enjoyed before that. Shortly after the blackthorn branches had been woven into the wooden framework, the brine started to trickle down over the infills and to create a gentle sea breeze at the Lower Rhine.

  Construction site information  
Building-owner Stadtwerke Kevelaer (municipal utility)  
Architect Groger Grund Schmidt architects. Kassel  
Roofing Grote GmbH & Co. KG, Weeze  
Material EVALON dual, slate gray; coated stainless steel sheets  

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