Attached Single Family Residence (SFR) is a term describing a single family residence that is built to the edge of the lot line next to another similar SFR on the edge of its lot, such that the two buildings are touching along an exterior wall. It differs from a town house in that each building is separate in and of itself, and could remain structurally even if the other were torn down. The two lots and homes together are often referred to as a “duet.”