TORONTO — The new headquarters for the Ontario Secondary School Teachers’ Federation is a state-of-the-art mass timber structure designed by Moriyama Teshima Architects. The 124,000-square-foot building prioritizes sustainability and wellness, utilizing abundant natural light and a structural connection to natural elements.

The architectural approach allows the cross-laminated timber and glue-laminated timber to serve as the defining elements of the interior. A clean, monochromatic palette was chosen specifically to highlight the natural beauty of the exposed wood. Key design features include:

• Exposed Structure: To keep the wooden ceilings visible, a raised floor system conceals all mechanical services, eliminating the need for unsightly overhead ducts.
• Natural Harmony: Interior finishes—such as neutral carpet tiles and stone-like textures—were selected to harmonize with the timber and evoke the surrounding ravine landscape.
• Acoustic Detail: The design incorporates walnut slat ceiling systems with integrated absorptive material to manage acoustics while maintaining the wood-forward aesthetic.

The interior, designed by Kasian, spans four floors on the building's north side, offering views of the Don Valley. A central full-height atrium is flanked by OSSTF offices and commercial tenant spaces. The layout emphasizes transparency, placing workstations in a bright, open perimeter that maximizes daylight. Custom millwork with subtle accents integrates the OSSTF brand.