This document reviews the arguments for and against timber and concrete as sustainable building materials. It considers aspects such as skill requirements for construction, material durability and longevity, CO2 emissions, and potential for CO2 absorption. The sources highlight concerns about the quality of timber construction in some areas and the potential for concrete to offer a more durable, and potentially self-healing, solution. The role of trees in carbon sequestration is acknowledged, while also pointing out that concrete can reabsorb CO2 over its lifespan.