The Barriers to Mass Timber Construction in High Rise Buildings

On Thursday 27th April Matt Orford, Associate, attended the second CTBUH roundtable discussion on “The Barriers to Mass Timber Construction in High Rise Buildings”. The first discussion, while interesting, was majority confined to discussions around difficulties with insurance and the fire engineering implications of using timber, and was slightly held back by not having any client representation in the room.

This second session was held at The Office Group’s Black & White Building with their co-founder Charlie Green in attendance, who gave some fascinating insights around their timber journey, and detailed that the building, which opened in January, is delivering revenue 40% above their underwrite. His view was clearly that developers are key to driving the move to timber, as it is not an easy ride.

Further topics of discussion were around acoustic performance, which Charlie Green stating that to date they have had no complaints despite having no screed or screed board on the CLT slab, and whether timber construction is being held back by onerous requirements for which there is little real life test data. Matt fed in here that the additional acoustic requirements on top of the fire engineered solutions are typically why timber options are discounted on cost grounds. There was also a good portion on ensuring timber elements are able to be re-used, so the sequestration can be taken into account in carbon analyses, and how to better design for demountability, a comment from a WSP structural engineer that they are working with B&K and University of Warwick to try and develop a design by which steel and CLT can work in a composite fashion to increase efficiency. It was also mentioned that hardwood CLT/Glulam, which could be grown and produced in the UK, have better charring performance and strength to weight ratios which may unlock the larger spans required for taller buildings, albeit at a cost premium.