A double-layer fabric roof helps solve the seasonal issue for a beach club on Holland’s coast.
By Mark Zeh
Recently a new type of trendy nightclub and restaurant has appeared on the coast of Holland: the beach club. The words beach club normally evoke thoughts of summer heat, light dress and casual eating fare, so it seems anomalous to imagine such clubs situated on the windward coast of the North Sea.
One of these is a beach club called Bries (“breeze” in English), located in Noordwijk, The Netherlands. It is a long, low shed-roofed, post-and-beam structure with glass infill along the sea view sides. The structure stands on concrete pads, covered with wooden decking that extends out of the structure to form an exterior sun deck. Eight wooden service boxes are arrayed along the non-ocean side of the structure. These contain cooking, storage and preparation areas. The interior of the structure contains retractable light curtain space dividers, allowing quick reconfiguration for various expected customer and staffing levels and special events.
The post and beam structural elements consist of composite weldings of stock steel profiles that have been double galvanized against corrosive attack from salt spray, and wooden beam composites with interior cable service routing. The composite post/beam elements are designed to accept wood-framed fenestration.
The common wooden plank floor of the club interior and outside deck act to provide continuity between outside and inside spaces. When weather is fair, the ocean-facing glass facade may be completely opened, allowing customers to experience the continuous space. When weather changes for the worse, the facade is closed.
And to top it off: The two-layer fabric roof of the structure keeps weather out, lets light in, and helps to maintain a constant temperature inside, usually without the need for additional heating.
New take, old idea
The beach clubs in The Netherlands are temporary structures—they are set up in March and taken down in October. By law they must be able to be erected, or removed, within a two-week time span; they are moved to storage and repaired over the winter. The concrete pad and threaded stainless steel mounts for the columns of the Bries remain on site year-round.
“In 2008, we had the opportunity to create a new type of beach club for friends of mine in Noordwijk, The Netherlands,” says Bart Akkerhuis of Studio Akkerhuis in Paris, France. “The brothers Michiel and Martijn van den Berg had been running a small beach club selling hamburgers and things and needed to refurbish it. They took this opportunity to create something more premium, with the vision of eliminating the barrier between inside and outside.”
“It was great to work with clients who had such a clear vision, but who were also so open,” says Philipp Molter of studiomolter in Munich, Germany, architectural collaborator with Bart Akkerhuis. “This enabled us to create a structure that is quite different than the other, rather traditionally constructed, clubs on the beach nearby.”
The layers of the double-layer fabric roof are separated by a minimum vertical distance of about 50cm, with the lower layer having a higher slope to promote drainage. The space between the membranes is open to allow air to flow naturally between the layers due to wind force and natural convection. This allows interior temperatures to remain constant despite varying solar loads and differing exterior temperatures.
“This concept is actually quite old,” explains Akkerhuis. “You’ll find double-layered roofs widely used in the tropics and Africa, where people commonly build structures with a ‘shade layer’ and a ‘rainproofing layer.’ However, these structures are never executed with light-transmissive materials. We’ve executed the idea with modern materials and in a very challenging environment—our club must survive
Force 12 winds (more than 73 mph). Also, summer weather on the coast of Holland can change very rapidly from sun to rain, so we have the need for people to be comfortable inside the building while the temperature outside can vary between 16° and 35°C (61° and 95°F). The temperature inside of the structure remains very constant, however. There is a heating system inside the club, but it’s rarely used.”
Time and materials
The double-skin roof of the structure is its most revolutionary feature. This consists of an upper fabric layer acting as a screen to absorb solar load and provide shade (Ferrari Soltis® in white) and a lower fabric layer acting to keep the weather out and allow light in (Ferrari Précontraint® in white). Both materials are PVC-coated polyesters.
“The Précontraint fabric is really key to executing the concept of ‘inside-outside’ and also one of the elements of the sustainability story of the structure,” says Molter. “It has very high light transmissivity (48 percent), which admits a great deal of light from the sky and even allows people inside the club to notice features in the sky, such as clouds, while keeping the temperature even. Due to the amount of light admitted, we don’t need to have a great deal of lighting inside the building. The ceiling plane is already quite bright. This is a new material from Ferrari and we may have been the first commercial user of it.”
“The upper layer of the roof was very straightforward to design,” says Patrick Teuffel, of Teuffel Engineering Consultants, Stuttgart, Germany, structural engineer for the Bries project. “It’s simply eight panels of the mesh fabric tensioned by a simple rectangular framework. The eight double-curved lower membrane sections were more of a challenge to design. The supporting tracks for the inner layer curve sharply toward the floor along their rear edge. Capturing the fabric in the curved sections and tensioning the panels evenly was really the big structural challenge, since the means of tensioning are located in the ‘back’ of the structure, on the roofs of the wooden service structures and between them.”
“The biggest challenge in the project was really time,” adds Akkerhuis. “Creating this club was a business decision by our clients, so we needed to complete design-development and construction time starting in the fall of 2008 and ending in May 2009. This was eight months, from concept development through a complete club on the beach in Noordwijk. This meant that we had to quickly arrive at a viable concept, find willing collaborators to co-develop and supply the components, and then construct the club on site.”
“We didn’t really have much time to test concepts,” says Teuffel. “We received samples of the materials so we were able to judge the light transmissivity and other properties. We also didn’t have time to do a simulation of the working of the convective cooling concept, but it’s quite conservative and works well.” He adds: “To me, one of the largest challenges was to design a structure that could be demounted every year. This means that the fabric roof is de-tensioned, stored and re-tensioned every year—something that probably wasn’t foreseen in the design of these materials. But it’s four years old now and everything still seems to be going well.”
“The biggest technical challenge we faced was getting the water sealing to work. The transition between wooden beams, aluminum fabric mounting tracks and the fabric took a bit of work to get right,” says Akkerhuis. “One thing that surprised me was the amount of sand that accumulates on the roof! The clients rather like how this looks, but if I could re-do the project, I’d try to find a solution so that less sand accumulated.”
“Maintenance of this structure is another component of the sustainability story,” says Molter. “The roof is just fabric, so there isn’t a lot of material involved if you need to repair or replace a piece. Also, the rest of the structure is made of lightweight steel or wooden components, all of which are rather simple. Every year, the company that sets the building up replaces the corroded bolts and cleans everything. During the seasons of operation, sand is occasionally pressure-washed from the roof. Otherwise, it’s really quite cost-efficient to maintain.”