Located in the heart of Vienna, in the historic flak tower in Esterházy Park, the House of the Sea uniquely combines nature, architecture, and history. A special highlight is the Tropical House – a glass extension that transports visitors to the fascinating world of tropical rainforests.

After more than 20 years of intensive use, this area underwent a comprehensive renovation in 2023. The goal was to preserve the tropical atmosphere while finding a durable, easy-care, and sustainable flooring solution. The choice fell on WPC decking from NaturinForm—a decision that delivers both aesthetic and technical performance.

The wood composite planks not only offer a natural look, but are also particularly resistant to moisture, non-slip, and splinter-free – perfect for an environment that is walked on barefoot by hundreds of visitors every day.

With this sustainable modernization, the tropical house of the Haus des Meeres remains a place of wonder and experience – for current and future generations.

The architectural concept of the Haus des Meeres is deeply rooted in the history of its site. The massive, gloomy flak tower from World War II has been complemented in recent decades by innovative extensions such as the glass tropical house and a modern glass-and-aluminum annex.

Viennese architect Ludwig Starz of Looping Architecture, responsible for planning and construction, describes the tower as "an opaque, massive concrete structure." In contrast, the glass extension, with its transparency and lightness, counters the heaviness of the flak tower. "The glass and aluminum façade symbolizes the shimmering sea and blends harmoniously into the urban environment," says the architect.

Completed in 2020, the extension houses elevators that provide barrier-free access to all levels. At the same time, it offers spectacular views of Vienna's city center—with St. Stephen's Cathedral as a particular highlight.

The Tropical House: an exciting journey through the jungle

A special highlight of the extension is the Tropical House, which leans against the west side of the tower like a "nose." Here, visitors are immersed in the world of tropical rainforests. The path leads from the second floor of the tower up into the treetops of the Tropical House and finally back to the main building.

As they go up and down the stairs, guests explore a tropical world: A waterfall trickles along the rocky landscapes, while monkeys, exotic birds, and turtles roam freely, allowing for close encounters. "You move from the ground and water level up to the treetops. This floating structure creates a unique spatial experience that is enthusiastically received by everyone," says Ludwig Starz.

Sustainable renovation project with WPC boards

After more than 20 years, the original wooden structure of the tropical house was severely damaged. High humidity had damaged the wood, necessitating extensive renovation. The project team opted for a sleek steel structure fitted with durable WPC (Wood Polymer Composite) planks from the German manufacturer NaturinForm.

The architect and operator of the Haus des Meeres made the choice of material together. Strong was used for the walkways, and Robust for the stairs, both in brown. Durability, ease of maintenance, and high slip resistance were crucial. "WPC is ideal for us because the plastic (polymer) content makes it resistant to moisture and lasts significantly longer than wood. The material also ensures safety – even under intensive use by animals and water," adds the architect.

"We wanted a material that was durable, easy to maintain, and sustainable," explains project manager Peter Neßmerak. "After 20 years, the wood was so badly damaged that replacement was essential. The new WPC decking from NaturinForm offers significantly greater resistance to moisture and wear."

Self-supporting construction for harmonious aesthetics

The steel structure allows for a cantilevered design, allowing building services and care facilities to be discreetly housed beneath the walkways. "Floors and ramps are suspended from the structure, creating an airy, light feeling of space," explains the architect.

The NaturinForm planks also impressed with their technical properties, which allow for larger spacing between the substructure supports. "It was the only product that met both our structural and aesthetic requirements," emphasizes Neßmerak. The natural look blends perfectly into the tropical surroundings.

Challenges in implementation

The renovation was particularly challenging because the House of the Sea remains open year-round. "It was like a puzzle—all the work had to be completed during ongoing operations, which required a logistical feat," reports Neßmerak. At the same time, the pathways were optimized: Gently sloping ramps with a maximum gradient of six percent ensured accessibility and a smooth visitor flow.

Precise assembly thanks to well-thought-out planning

The planks were mounted on galvanized, coated steel beams, to which the manufacturer's specially developed mounting profiles were attached. NaturinForm not only supplied the fastening materials but also installation plans precisely tailored to the project, minimizing waste.

"The mounting profiles and accessories from NaturinForm made the work much easier," says Neßmerak. "In particular, precisely adjusting the planks to the irregular angles and non-parallel profiles was a challenge, which we were able to overcome easily thanks to the tools and plans provided."

The entire renovation, including demolition work, took eight months. The experienced steel construction company Josef Pichler from Kirchschlag handled the installation of the decking. "The installation was challenging, as there were hardly any side finishes and many areas had individual slopes," explains Neßmerak. "However, thanks to the thoughtful planning and high-quality materials from NaturinForm, we achieved an outstanding result."

An impressive world of experience for humans and animals

The redesign of the tropical house was well received not only by visitors but also by its animal residents. "It's amazing how quickly the animals have adapted to the new surroundings," says the Haus des Meeres team. Monkeys use the new walkways as observation points, while turtles move freely in the landscaped landing areas. The natural look of the NaturinForm floorboards contributes to a harmonious overall appearance.

“Visitors now stay longer in the tropical house, enjoy the atmosphere and experience the tropical diversity more intensively,” reports Zoo Director Dr. Michael Mitic.

Future perspectives: Sustainability as a guiding principle

With the renovation of the tropical house, the House of the Sea is setting new standards in sustainable architecture and visitor friendliness. "In a few years, the tropical house will once again be completely overgrown with plants, offering an even more intense jungle atmosphere," predicts the architect.

The House of the Sea thus remains not only an important institution in Vienna, but also a pioneer for the successful combination of nature, architecture and history.

Conclusion: a sustainable showcase project

"We made the right choice with NaturinForm's WPC decking," Neßmerak summarizes. "The decking meets all our requirements: slip resistance, durability, and maintenance-free operation. Even daily cleaning with a pressure washer works perfectly."

Thanks to the easy-care, durable, and environmentally friendly materials, the Tropical House is committed to a sustainable future. "We have found the perfect product for our Tropical House—it will accompany us for decades."