By:  Joseph E. Caza III, PE, Partner

Recently, Elwyn and Palmer Consulting Engineer made the decision to utilize the Peikko DELTABEAM system for a new four-story, 58,000-square-foot mass timber office building. The primary mass timber structure is composed of CLT shear walls and glulam columns up through the third floor. As a cost-saving measure, and because there’s less need for future space flexibility on the top level, the fourth story will be light wood-frame construction.

One of the most significant constraints we ran into was the coordination and design impact of glulam beams spanning between columns. Those beams can become large once you account for both the strength demands and the required char depth inherent to mass timber fire design. That increased depth doesn’t just affect the structure; it quickly turns into a ceiling/MEP coordination problem, especially in areas where services are dense or floor-to-floor height is limited.

The DELTABEAM helps alleviate that issue by using a steel beam encased with reinforced concrete that sits in the same plane as the CLT floor panels (a slim-floor approach). By keeping the structural depth more efficient, it reduces the downstream impacts on coordination and gives the team a cleaner path through the most congested zones, without giving up the span capability we need.