Completed in 2015, Puukuokka One marked a turning point in Finnish architecture as the country’s first eight-story wooden apartment building. Designed by OOPEAA and built using Stora Enso’s prefabricated cross-laminated timber (CLT), Puukuokka received the Finlandia Prize for Architecture, Finland’s highest architectural honour. It has since been featured in numerous international publications focused on sustainable design, modular construction, and carbon-conscious architecture.

Located in the Jyväskylä suburb of Kuokkala, the Puukuokka complex was completed in three phases: One in 2015, Two in 2017, and Three in 2018. Together, the buildings form a unified block that integrates seamlessly with the surrounding landscape of hills and lake, while anchoring the neighborhood alongside the Kuokkala Church (OOPEAA, 2010).

Modular system prototype

Puukuokka served as a pilot project for a CLT-based volumetric modular system. Each apartment consists of two modules: one containing the living room, balcony, and bedroom; the other housing the kitchen, bathroom, and foyer. These modules were prefabricated in a local factory in Hartola and transported to the site within the dimensional limits set by Finnish road regulations.

Accelerated Construction Process

The use of prefabricated CLT modules enabled a construction time of just six months per building, significantly reducing on-site labor and exposure to weather. The result was a high-quality finish with minimal disruption. Even the façade elements were prefabricated and delivered ready for installation. The hallway, the only part built entirely on site, features a full-height atrium that brings in natural light and creates a semi-warm communal space.

Carbon storing design

Thanks to the insulating properties of massive wood, Puukuokka achieves high energy efficiency. The semi-warm hallway maintains a lower temperature than the apartments without affecting indoor comfort. Each unit has independent temperature control, optimizing energy use-especially critical in Finland's cold climate.

Integrated building systems

All technical systems-heat, water, electricity, and ventilation-are integrated within the hallway's wall structure, allowing for easy maintenance and efficient spatial organization. The recessed balconies enhance daylighting and help define functional zones within each apartment.

Social sustainability model

Puukuokka offers homes for 184 households, ranging from single dwellers to families. It introduced a lease-to-own financing model, promoting long-term residency and community stability. The architectural layout balances the privacy of single-family homes with the communal character of shared spaces, fostering a sense of belonging and spatial richness.

LCA-Guided Development

The design process was guided by Life Cycle Assessment (LCA) and energy modeling. Various configurations were tested to optimize both environmental performance and spatial quality. The prefabrication process allowed for controlled indoor production, minimizing exposure to humidity and ensuring consistent quality.

Legacy

Puukuokka stands as a reference case for mass timber architecture, demonstrating how Stora Enso's CLT technology-now branded as the Sylva™ Kit of Parts-can be used to create high-quality, low-carbon buildings at scale. While Puukuokka pioneered this system in the context of social housing, the same Sylva kit has since been used in over 2,000 projects annually, including Stora Enso's own head office, which has also been shortlisted for the Finlandia Prize for Architecture 2025 (10 years later). This trajectory underscores Puukuokka's enduring legacy as a catalyst for innovation carbon storing design. 

Publications

Puukuokka has been featured in several notable architectural publications, especially those focused on carbon storing design and sustainability. Here are the most relevant ones:

Carbon: A Field Manual for Designers and Builders Authored by Kuittinen, Organschi, and Ruff, published by John Wiley & Sons, this book includes Puukuokka as one of two major case studies in decarbonized construction.

An Architecture Guide to the UN 17 Sustainable Development Goals - Volume 2 Published by the Royal Danish Academy in collaboration with the UIA World Congress of Architects, this guide features Puukuokka as a model for Goal 11: Sustainable Cities and Communities

Dezeen: Finland's tallest wooden apartment block wins Flinadia Prize.

ArchDaily: Detailed architectural breakdown of Puukuokka's design, materials, and social impact.