Architectural Record Features Thornton Tomasetti’s GreenBox Mass Timber Floor System

Architectural Record’s November 2026 issue features GreenBox®, Thornton Tomasetti’s low-carbon mass timber floor system designed to integrate structural and building-performance functions in one prefabricated assembly. 

Developed through an R&D initiative led by Harry Crofton, an associate in Thornton Tomasetti’s London office, GreenBox combines plywood sheets bonded to glulam joists with specially engineered fill. The assembly integrates fire resistance, acoustic insulation, and vibration control. It is designed to span approximately 30 feet and provide 90-minute fire resistance without additional fire protection or concrete toppings. 

Lightweight and designed for disassembly and reuse, GreenBox® offers a potential solution for vertical extensions of existing buildings, where reducing added structural weight and floor depth is important.

Connect with our team to explore how GreenBox can support your design and performance goals