By the end of the century, there will be a need for over two billion more houses. Three key factors are driving the need. The first may be the most obvious. Current estimates are for 50% growth in the number of people to about 11.2 billion. Second, as living standards improve, the number of people per household shrinks. Third, as life expectancy and overall health increase, people are using houses longer. Combined, that means over two billion more houses, which also means more land converted for residences, more resources devoted to building houses, and more energy spent on building and sustaining them. The projection is based on a series of assumptions that will undoubtedly change with urbanization, off-grid housing, prefabrication or robotic construction, and new technologies and materials. At the same time, climate change is shifting habitable zones requiring the abandonment of existing houses. The impact has the potential to be enormous for people, economies, the planet – and even careers.