Case Study: Rockrose unifies two Manhattan towers with Thornton Tomasetti structural renewal

Rockrose unifies 420,000 ft² at 11 East 26th Street with Thornton Tomasetti

Thornton Tomasetti was engaged by Rockrose to address the significant structural challenges of unifying two adjacent historic office towers at 11 and 15 East 26th Street in Manhattan into a single commercial destination. The project required reconciling decades of inconsistent alterations and incomplete documentation while both towers remained operational. Key hurdles included navigating strict landmark preservation constraints, connecting mismatched floor elevations, and accommodating new program demands like rooftop amenities within the existing structural framework.

Thornton Tomasetti's solution involved a performance-driven design focused on early investigation, preserving viable historic capacity, and introducing reinforcement only where necessary. Their structural engineering services included implementing discreet steel transfers to restore the historic façade, creating engineered openings to unify the tenant experience across both autonomous towers, and performing load-path analysis to enable new rooftop amenities. The result was a successfully unified, high-performing 420,000-square-foot complex that delivers modern performance within its landmarked envelope, preserving historic fabric while adding long-term value and tenant experience.

Rockrose