In the United States, the Federal Aviation Administration (FAA) defines Residential Through-the-Fence or RTTF as Access granted to a federally-obligated, public airfield from private, residential property or property zoned for residential use.[1]
These are usually private hangars, often built adjacent to, or as part of a house, allowing aircraft owners immediate access to their aircraft and an airport, without having to drive to the airport.
The aircraft does not actually have to pass through a fence to qualify as an RTTF operation. This term is used only because most federally funded airports have a fence enclosing the entire property, that users on adjacent private property will have to pass through.
The FAA is currently reviewing RTTF policies. While airports where RTTF access is currently allowed will probably be allowed to continue providing such access, new applications will most likely be denied, as part of increasing levels of security at even smaller airports.