Ongoing urbanisation requires rapid, low-emission construction methods. Architects, investors and politicians are on the hunt for housing solutions that are fast and cost-effective, yet sustainable and flexible. Timber room modules meet all of these requirements: flexibility, variability, low construction and operating costs, short construction times thanks to high rates of prefabrication, a pleasant living environment, easy dismantling via detachable connections, excellent recyclability as well as a general acceptance by end users. This practical volume offers an overview, from the planning process to assembly, while contemporary examples show that building with room modules facilitates heretofore unimagined, multi-layered and differentiated architectures.