“Accessory dwelling units (ADU) are small homes that can be built in the backyards of larger homes, in cities where they’ve been approved. They’re also sometimes known as carriage, coach, or laneway houses.
These small homes are typically around 700-1000 square feet in size, although the size sometimes has to be calculated as a percentage of the size of the yard.
Adding new homes in potentially underused backyard spaces is a sustainable way to provide more housing options in walkable urban neighbourhoods where people don’t need to use cars to get around for every errand. ADUs can also help reduce urban sprawl by reducing the need for cities to grow outwards, which increases commuting distances and therefore increases transportation pollution.”