ABSTRACT
Timber comes from the harvested wooden logs of tree trunks. Traditionally a lot of slow-growing hardwood trees were used for building, due to the longevity of the timber and the densely packed cells in the timber. The timber industry routinely processes many fast-growing evergreen softwood conifers such as Pinus radiata or Picea glauca. Timber columns need to have immense strength and stability primarily in one direction–vertically–and so Laminated Veneer Lumber (LVL) and Glulam are the only options, as their timber grain is all oriented the same way: vertically up the column. Timber beams in tall buildings are going to be either LVL or Glulam, again, because all the timber cells are going in one direction–horizontally. In multi-storey timber buildings, while a Cross Laminated Timber (CLT) floor over LVL beams will provide a perfectly adequate structural solution, in most cases a small concrete topping layer is added to the upper surface of the CLT, around 60mm thick.
