OSSTF Headquarters: A sustainable mass timber workplace

The new Ontario Secondary School Teachers’ Federation (OSSTF) headquarters brings together the relocation and revitalization of OSSTF’s central office alongside commercial tenancy opportunities within a mass timber structure. 

The three-storey building prioritizes health, wellness, and sustainability through abundant natural light, flexibility of use, and state-of-the-art systems. Working closely with design architects Moriyama Teshima, Kasian ensured the interior design of OSSTF’s new workplace was holistically integrated into the architectural vision while centred on the human experience. 

OSSTF’s new offices span four floors and offer westward views of Toronto’s Don Valley ravine. A central full-height atrium provides ease of circulation and is flanked by commercial office space. The building’s interior architecture, combined with its shallow floorplates, allows natural daylight to penetrate deep into the open space, promoting health and wellbeing for all occupants. 

The 40,000-square-foot interior supports OSSTF’s forward-thinking goals through a sustainable, health-conscious, and socially attuned environment, blending functionality with timeless sophistication.  

The cross-laminated and glue-laminated timber structure is the defining element of the space, complemented by a clean, monochromatic palette that highlights the natural beauty of exposed wood. OSSTF’s identity is subtly referenced through accent colours and custom millwork. 

Finishes evoke the surrounding ravine landscape with subdued tones, soft greys, and neutral floor finishes. Key destination spaces are defined by feature walnut ceiling treatment that add contrast and warmth, while providing sound-absorbing properties. 

Shared and arrival spaces, including a custom stone-finish reception desk, offer a bright, welcoming first impression. Offices are arranged around an outer band of workstations for transparency while flexible meeting rooms and distinctive kitchenettes reinforce brand identity and wayfinding. Meeting rooms are outfitted with a variety of furniture types and lighting that offer diverse work settings with a balance of functionality and aesthetic appeal. 

The building’s flexible, accessible infrastructure is concealed beneath elegant finishes, leaving the wooden ceiling exposed. Advanced building systems support net-zero carbon strategies, targeting LEED Platinum certification and high-energy performance levels. 

The progressive, future-ready workplace reflects the strength, professionalism, and values of the organization while embracing the warmth and integrity of the building material. 

Photos by Tom Arban