Tallest wooden building

The tallest wooden building is Ascent, a 284-ft (86.6-m) apartment complex in Milwaukee, Wisconsin, USA. The structure is classified as a timber-concrete hybrid by the CTBUH, as the timber structure sits on five stories of concrete construction and uses reinforced concrete for the lift/service towers. The rest of the structure, which was designed by Korb + Associates Architects and engineered by Thornton Tomasetti (both USA), is made from engineered timber. It was completed on 20 July 2022.

The building's structural frame is made from glue-laminated timber (GLT or "glulam") and cross-laminated timber (CLT). The difference between GLT and CLT is the orientation of the sawn boards used. In a GLT beam, the grain direction of all the boards are aligned for maximum strength along a single axis. In CLT, every other layer is rotated 90 degrees, making the board equally strong in all directions. These laminated structural materials are stronger than traditional timbers, more consistent in the forces they can withstand and can be made to any size or shape. These qualities make them suitable for use in high-rise buildings.

In a modern mass timber structure, GLT is typically used for structural elements that are under tension, such as floor beams, while CLT is used for elements that are under compression, such as pillars and walls.

Timber (when sourced from managed forests) is a much more environmentally friendly material than steel or concrete. The creation of glue-laminated timber beams requires much less embodied energy than steel or concrete of equivalent strength. Furthermore, timber is itself a carbon sink – the element, which trees extract from the air as part of photosynthesis, makes up between 40 and 50% of the dry weight of timber.