Abstract: Devices, systems, and methods related to a fenestration unit are described herein. The fenestration unit may include a horizontal member and a vertical member that intersect at a corner. The fenestration unit may include an end cap coupled within an access opening including a housing including a horizontal housing portion and vertical housing portion, the horizontal housing portion coupled to a seal and the vertical housing portion defining a cover operable to cover the access opening. The fenestration unit may include a corner block operable to couple the horizontal member and the vertical member including a body including a top portion, a first side portion, a second side portion, and a bottom portion, the body defining a plurality of cavities, the plurality of cavities each operable to receive a fastener therethrough.

Abstract: Devices, systems, and methods related to a fenestration unit are described herein. The fenestration unit may include a frame including a plurality of frame members, wherein the plurality of frame members includes an upper rail member, a lower rail member, a first stile member, a second stile member, the lower rail member including two parallel metallic extrusions a space defined therebetween and a thermal break coupled to the lower rail member and located within the space. The thermal break may include a solid body of thermally insulating material defining a first side portion, a second side portion, and an intermediate portion between the first side portion and the second side portion, the solid body of thermally insulating material being asymmetrical about an X-Y plane.