The United States has a large supply of residential garages that could be converted into affordable apartments. Unfortunately, off-street parking requirements prohibit converting most of these garages for cars into housing for people. Converted garages in single-family neighborhoods are variously called second units, accessory dwelling units, garage apartments, granny flats, and backyard cottages. To convert a garage into an apartment, off-street parking requirements typically force a homeowner to replace the two garage parking spaces with two new parking spaces, plus an additional off-stre...