Aquila Mobile Sauna Project Reinvents the Traditional Finnish Bathing Ritual Experience
Mobile Sauna Combining Design and Traditional Finnish Culture
The latest creation by architect Rupert McKelvie is located at the intersection of architectural statement and wellness retreat. The Aquila project, a mobile sauna by Out of the Valley studio in Devon, represents an attempt to transform the traditional Finnish ritual of hot bathing into a portable experience that can be towed behind a truck. This initiative demonstrates that authentic bathing culture does not necessarily rely on permanent infrastructure, it can be transported to lake shores, coastal cliffs, and forest clearings across the UK.
Compact Design and Innovative Techniques
The structure is built on a 3.8-meter-long twin-axle trailer and accommodates up to six people, with full off-grid operation capability. The exterior cladding of the sauna features black larch wood treated with the Japanese Yakisugi (shou sugi ban) technique, providing additional protection and a distinctive carbonized appearance. Learn more about building materials suitable for such applications.
Engineering and Mechanical Challenges
One of the standout innovations in the design is the foldable roof system, which required multiple prototypes to achieve the final design. McKelvie admitted that this stage was the most challenging, as it involved continuous testing to ensure the mechanism could withstand repeated assembly and disassembly without malfunction. This process relates closely to best practices in construction and mechanical engineering within architectural projects.
The Evolution of Out of the Valley Studio
Rupert McKelvie founded Out of the Valley six years ago, after creating his first personal wooden cabin near Dartmoor National Park. This small project sparked the vision for a larger architectural approach, with McKelvie’s practice evolving into a full-fledged studio focused on handcrafted structures that work in harmony with natural materials rather than resisting them.
To date, the Aquila project represents the studio’s most ambitious output and has received international recognition after being longlisted for the Dezeen Awards 2025 in the Health & Wellness Product and Wearable category, competing against over 4,300 entries from 89 countries.
Materials and Interior Techniques
Inside, the walls are clad in thermally modified alder, specifically chosen to withstand extreme temperature variations without warping or splitting, reflecting the studio’s commitment to durability and sustainability. A 16 kW Narvi wood-burning stove serves as the focal point of the sauna, delivering the authentic heat that is difficult to replicate with electric alternatives. Additionally, the precision LED lighting unit is powered by solar panels, allowing the sauna to operate at any location without relying on external power sources. For more on material datasheets, see our reference library.
The Traditional Bathing Experience
To complement the authentic sauna experience, a rear panel folds down to form an entry platform, while the integrated cold shower completes the traditional thermal contrast ritual, an essential part of the Finnish bathing practice.
Smart Design Details
The Aquila design stands out by integrating clever details without overdoing it, ensuring that every feature serves a practical purpose without overwhelming the visual composition. For example, the perforated storage area at the trailer’s end holds firewood for multiple sessions, while the foldable roof protects all contents during transport and adds a striking visual element when deployed.
Balancing Footprint and Comfort
The compact footprint allows the unit to access remote locations while maintaining comfortable interior capacity. This balance between small size and comfort presents a significant challenge when working within the constraints of a trailer, highlighting the design’s ingenuity in utilizing every centimeter practically and aesthetically. The approach reflects principles often discussed in interior design projects.
Collaboration and Practical Expertise
In recent months, Out of the Valley studio has participated in experimental projects in collaboration with lifestyle brands, providing the units access to Lake District National Park and offering visitors a unique experience at selected accommodations. Such collaborations are commonly highlighted in events and industry showcases.
Handcrafted Production and Customization Options
Each unit is handcrafted in the studio workshops, with a current delivery time of around four months. The design can be tailored to user needs, including door orientation and heating preferences, reflecting a clear focus on customization and high-quality craftsmanship. Similar projects are frequently featured under archive collections of innovative portable designs.
✦ ArchUp Editorial Insight
From an architectural perspective, the Aquila mobile sauna project presents an intriguing model for integrating practical design with the traditional Finnish ritual of hot bathing. Attention to small details, such as interior materials resistant to temperature fluctuations and a solar-powered independent lighting system, reflects the studio’s commitment to sustainability and functionality. For ongoing discussions, visit our discussion section.
However, certain aspects raise questions about scalability and practical applicability in different contexts. While the compact footprint enables access to remote locations, it may limit comfort or usable space for everyday use. Similarly, the handcrafted construction and high level of customization may increase costs and restrict widespread adoption.
Nevertheless, practitioners and architecture enthusiasts can draw inspiration from Aquila in terms of combining functional flexibility with sustainable materials in portable projects. It also offers a valuable case study on how cultural ritual concepts can be translated into practical models for diverse environments, providing a solid foundation for future experiments in small mobile units or temporary settings.
