As mentioned previously, the development of composites has been led for decades by the marine industry, and there have been numerous crossovers of both people and ideas from the realm of composite boats to composite building materials.
Deutsche Composite GmbH, a German company, is straddling the divide with a new composite sandwich-panel building system called Rexwall that is being applied to both houseboats and land-based housing.
Rexwall is a sandwich panel system consisting of 80mm of core with two 1.2mm glass fiber composite skins made with epoxy resin. The heart of this system is a patented design that creates a pre-laminated “beam,” a narrow sandwich panel made of a core and two composite facings, similar to the overall wall construction. This beam is as wide as the thickness of the wall core material, so the beam can be placed as part of the core of the wall panel with its stiff composite skins rotated 90%, oriented perpendicular to the wall panel facings. This adds additional stiffness to the wall panel across its thin dimension.
Most composite sandwich panels currently are constructed around a core of rigid foam. Rexwall has taken the innovative step of using a natural cork core. Cork is fire resistant. Where a foam-cored panel would have about 10 minutes of fire resistance, the cork-cored panels tests at 2 hours. Cork has excellent thermal and acoustic insulation properties, as well. Moreover, it is a renewable resource. Rexwall’s cork-cored panels are 98% natural material (an especially good selling point in eco-conscious Europe).
The Rexwall system is licensed to various manufacturing partners. One of them makes the CabinCube, a 2.5 m (8 foot) composite cube that is a complete – if small – residential chamber. There are several different models of cube featuring varying amounts of glazing, and even decorative architectural cladding. Cubes are sold for a variety of different purposes including private guest-houses and hotels.
One of their very first projects was an economy hotel in Berlin, a flat piece of ground with an array of bedroom and service cubes arranged on it. The company now has three such hotels, the largest consisting of 50 cubes. The 2.5-meter (6.25 m2/67 sf) rooms feature infrared heating, automatic air ventilation, electric power, a 1-meter shower-bath, and sliding door. If that seems like a very small hotel room, well, it is. But so are many hotel rooms in Europe, and not just in economy hotels. In January, when there are many back-pack travelers looking for rooms, the Berlin hotel cubes are 80% booked.
According to Deitmar Kleenlof, Managing Director of Deutsche Composite, the creation of such a hotel is very fast. The light, small cubes can be transported five-on-a-truck. Because they are complete rooms including a floor, they can be simply placed on the ground with little or no foundation. (In Europe, these cubes do not even require permitting for some applications, although hotels must acquire permits.) “They deliver the cubes,” says Kleenlof, “and the next day they rent it out.”
“It’s something between a hotel and the camping industry,” says Kleenlof. “The guests span from young partiers to retired people on a budget.”
Their next project is a development in Bavaria for refugees. Another Cube Cabin hotel soon-to-be-built in Berlin will have a minimum of 150 cubes. Another is being built in Portugal with air conditioners mounted on the roofs.
Rexwall technology is not limited to small structures, either. Their houseboats are considerably larger, and full-sized houses are also possible… and very fast to erect. “We build a 50m2 house in five or six hours,” explains Kleenlof. The individual panels get laminated together for a solid construction. Although the company is focusing on small, transportable structures in Europe (to avoid problems with building codes), in Latin America and Asia, they expect to build larger, permanent buildings.
Kleenlof sees this building system as a contribution to solving the world housing crisis. “I don’t think we in the Western world will accept living in plastic houses. Not yet.” But the need for shelter in developing countries is enormous. He describes an upcoming social housing project in India that will include 100,000 houses, and take approximately three years to build.
Images courtesy of Deutsche Composite GmbH