The construction industry has been a major contributor to resource consumption and global greenhouse gas (GHG) emissions, owed to high demand for building construction and the rapid urbanization trend. Timber construction has gained traction globally due to environmental advantages, such as renewability and carbon sequestration. However, sustainably available wood resources are limited. Extension of service life of timber structures is key to prolong their carbon stock. This paper showcases research projects carried out in Australia and Sweden that aim to design adaptable timber buildings capable of accommodating functional and spatial changes over time, thereby extending the service life of buildings and their components, as well as optimising their life cycles through spatial variations and repair of local damages to structural elements. This approach, known as Design for Adaptation (DfA) is an important step of the roadmap towards circular design solutions for timber buildings, which provide many economic, social and environmental benefits to all stakeholders and key players related to the building process, including manufacturers, engineers, architects, end-users, municipalities, and others.