Fenestration unit including slidable glass panels

A fenestration unit comprising:

• a first glass unit;
• a first panel frame circumscribing the first glass unit;
• a second glass unit;
• a second panel frame circumscribing the second glass unit;
• a sill flashing;
• and
• a frame circumscribing the first panel frame and the second panel frame, the frame including a header, jambs, a frame sill including a first track and a second track, and sill corner blocks arranged to align the frame sill on the sill flashing, wherein the first panel frame and the first glass unit are slidable along the first track when positioned in the frame, wherein the second panel frame and the second glass unit are slidable along the second track when positioned in the frame,
• wherein the sill flashing includes a base extending under the first and second tracks and a wall extending upward from an edge of the base to inhibit moisture intrusion through the fenestration unit, the frame sill is sized to entirely cover the base and the wall of the sill flashing, and
• wherein the frame sill is removable from the frame without disassembling the sill flashing, the jambs, and the header.