What is a housing co op?

It is relatively difficult to start a housing co-op because if the idea is, for instance, to build a building or group of buildings to house the members, this usually takes a significant mortgage for which a financial institution will want assurances of responsibility. It may also take a year or more for the members to organize the design and construction, as well as time and foresight to establish even basic organizational policies. It is rare that these kinds of skills of organization are available in a random group of people who often have pressures on their existing housing. It may be somewhat easier to organize a group of closely related housing units. This opportunity may arise, for example, if an existing apartment building's owner is thinking about selling it.