In order to understand how policies could deliver the increased rate of buildings efficiency retrofit, it is useful to learn the drivers of this process. This report examines the decision-making process of thermal efficiency retrofit among owners of single- and two-family homes of Germany. It is based on a survey of 2,000 households that have been divided into three categories based on where they were in this process. We conclude that motivations and financial reasons for engaging in thermal efficiency retrofits change as households go through its process. The usefulness of particular information sources also changes over time. The implication is that policy tools should be tailored to specific barriers and opportunities associated with different stages of the decision-making process of buildings thermal efficiency retrofit.