a bit more than a little.
The Tall Wood design relies on steel and concrete. Obviously not as much as a traditional high rise, but the floors use concrete topping - 2"+ - and a steel wide flange along the perimeter and back to the core.
The charring rate was calculated at 0.65mm / min, or 78mm total depth (3 inches) after 2 hours without intervention. Much of the detailing shows traditional gypsum wallboard sheathing, so it's not all that different from protecting steel structural elements, to overcome the reduction of structural strength of timber, resulting from fire.
I can think of many ways that the proposed savings / sf would be diminished, if not entirely used up:
1. Cost of familiarity of construction. Unless this style of construction caught on, everyone from Architect, Engineer to Contractor will find it difficult to design and build without stumbling along the way and incurring high revision costs / delays.
2. IBC and complete test documentation. Without revisions to the IBC, in the US the difficulty will be providing the necessary information and proof of the system, to building code officials. Without complete test documentation from UL and a series of unified means of construction / materials from ASTM and others, the argument from the code official will be: You're asking me to trust you?
3. Software. BIM would require a dedicated Tall Wood library. Someone needs to get the ball rolling on this, if complex high rises are ever to catch on.
These aren't insurmountable obstacles, but they will need to be addressed fully, and that will take some time.
