Overview
Entrant:
PTL | Structural & Fire
Category:
05. Innovative Timber Manufacturing & Technology Award
Photographed by:
Holzius
Key team members:
Structural Engineers: Silvia Baldini, Daniel Moroder, Andy Buchanan (PTL Structural & Fire)
Architectural Designer: Nina Conradi (ARTistARCHITECTURE)
Wall and Floor Panel Manufacturing: Holzius, Italy
Builder: Kawhata Williams (Niche Design & Construction Ltd)
The Conradi Holzhaus in Wānaka is a three-storey family home that brings together natural living, advanced timber engineering, and precision manufacturing.
Set on a steep site near Wanaka, the project began with a clear vision: to create a healthy, toxin-free, warm and nurturing home, simple in form, natural in materiality, and efficient in performance. Inspired by nature and guided by the client’s desire to build “as close as possible to living in the forest,” the design sought a construction system capable of delivering comfort, sustainability, and beauty through solid wood.
The holzius system was chosen for its alignment with this vision. Developed in the European Alps, holzius merges traditional solid timber know-how with modern CNC machining to create a fully glue-free, metal-free mass timber building method. This system enables architecturally refined, high-performance structures using nothing but natural wood. For the client, its combination of warmth, strength, and technological precision made it the ideal solution to produce a home that feels natural, breathable, and grounded in its material essence.
All external and internal load-bearing walls are formed from untreated European spruce planks, joined side-by-side with tongue-and-groove joints and interlocked across layers with continuous linear dovetail timber connectors. These dry mechanical connections swell into place due to controlled moisture content, forming dimensionally stable, monolithic wall assemblies without adhesives. Floor and roof elements consist of interlocking wooden beams connected through tongue-and-groove joints and threaded rods made of beech providing clamping action. Together, these systems create a strong, airtight, glue-free structure carrying Cradle to Cradle Certified® Gold recognition for natural composition, recyclability, and responsible production.
This manufacturing approach is the project’s core innovation. Timber’s unique machinability and anisotropic behaviour allow for precise CNC-cut geometries that interlock mechanically, impossible to replicate in concrete or steel. These dry jointed elements provide robust shear transfer, seismic resilience, and predictable stiffness without chemical bonding. Prefabrication ensures millimetre accuracy, rapid assembly, and minimal waste, which proved especially valuable on this steep hillside site.
These advances in precision timber fabrication of mechanically interlocked systems have only recently enabled a fully glue-free solid-timber structure at multi-storey scale, which would not have been achievable in earlier decades. The Conradi Holzhaus shows how these developments elevate natural solid wood into a modern, durable, high performance construction system that supports healthy interiors, circular material use, and low-carbon design.
The home’s form and layout are shaped by timber’s ability to provide structure, enclosure, and interior finish in one element. The lightweight system suits the steep site, while the holzius floor plates deliver diaphragm action equal to monolithic materials. Timber’s warmth, breathability, and hygroscopic behaviour ensure a stable, energy-efficient indoor climate without synthetic treatments.
For the client, the result is “a fusion of the highest standards of comfort and engineering, the closest you can get to living in the forest.” It is a testament to the beauty and strength of solid natural wood and to the collaboration that made this dream home a reality.