Structures for the isolation of a fin-type field-effect transistor and methods of forming isolation for a fin-type field-effect transistor. A first dielectric layer is formed that encapsulates a plurality of fins. A second dielectric layer is formed that surrounds the first dielectric layer and the plurality of fins. A surface of the second dielectric layer relative to a surface of the first dielectric layer. A liner is conformally deposited on the surface of the first dielectric layer and on the recessed surface of the second dielectric layer. A section of the liner is removed to expose the surface of the first dielectric layer. The exposed surface of the first dielectric layer is recessed to reveal a portion of each of the plurality of fins.