Hajime Construction Unveils Innovative HW5.0Σ Structure for Housing

Hajime Construction's Game-Changing HW5.0Σ

Hajime Construction, a core entity of the Iida Group Holdings, recently hosted a press event on October 14, 2025, to unveil its self-developed seismic-resistant wall, HW5.0Σ. In a time where narrow housing construction in the Tokyo metropolitan area is continually on the rise, this innovative wall system aims to improve design flexibility, reduce costs, and enhance durability.

Growing Demand for Compact Housing

Tokyo's urban landscape is evolving, with new builds of single-family homes on small plots (30 to 50 square meters) set to reach 1,107 units by 2024. This represents an approximate 30% increase compared to the statistics from 2015. The unveiling event showcased how HW5.0Σ is being implemented in a three-story residential building under construction in Itabashi Ward, Tokyo.

The Motivation Behind HW5.0Σ

Hajime Construction has dedicated efforts to provide homes that not only meet seismic grade three safety standards but also offer superior environmental performance. Previously, the company had focused on the development of ministerial-certified exterior walls. In June 2025, they turned their attention to internal bracing systems, leading to the creation of the HW5.0Σ, which aims to tackle practical challenges such as optimizing routing for utilities while emphasizing usability in housing design.

Key Features of HW5.0Σ

Achieving the ministerial certification in June 2025, the HW5.0Σ has become the first internally braced wall system with a wall ratio of 5.0 certified in Japan. This technology is characterized by exceptional strength, flexibility, and rigidity, which not only expands design possibilities but also minimizes the amount of wood used in construction while maintaining high seismic performance at reduced costs. By utilizing domestically produced LVL (laminated veneer lumber) materials for its diagonal wood members, the quality and reliability of the structure are further enhanced.

Hajime Construction remains committed to advancing housing design freedom through innovative technology, continually providing customized solutions to meet client needs. The unveiling of HW5.0Σ is a testament to their dedication to the construction industry's future.

Company Overview

Hajime Construction Co., Ltd.
CEO: Tadami Horiguchi
Headquarters: 2-25-5 Minami Ikebukuro, Toshima-ku, Tokyo 171-0022
Established: February 13, 1967
Capital: ¥3.298 billion

Business Segments:

- Ready-built single-family homes: View More
- Condominiums: View More
- Custom-built homes: View More
- Renovation and transformation: View More
- Asset solutions for investment: View More
- Leaseback Plus⁺: View More

The launch event on October 14, 2025, showcased the practical application of HW5.0Σ, emphasizing a step forward in residential construction that combines safety, affordability, and innovative design approaches.