When the State Department sends you overseas to work, the U.S. Government will provide housing to you free of charge. The size of your residence will depend on your rank and family size.
Since most people reading this will be just starting out, I’m going to focus on sizing for “Standard” rank officers, as opposed to “Middle” and “Executive” rank officers.
NOTE: The State Department will accommodate ALL your direct dependents and will not discriminate your housing assignment based on family size. Married with seven kids and a dog? No worries, the Department is obligated to accommodate your spouse and kids, although Fido will have to squeeze in somehow.
The official regulation for allocating residential space is called 15 FAM 230: ALLOCATING RESIDENTIAL SPACE (PDF file).
Below are space standards for “Standard” rank officers in three different localities as defined in 15 FAM 230, above.
Locality 1 (e.g. Buenos Aires, Melbourne, Brussels)
Locality 2 (e.g. Nassau, Sarajevo, Sao Paulo)
Locality 3 (e.g. Phnom Penh, Kinshasa, New Delhi)
This policy was intended to ensure officers have adequate residences for the care of their families and not necessarily an incentive to encourage people to have more children!