Fenestration unit with plural panels and interpanel coupling system

A method of manufacturing a fenestration unit comprising:

• providing a frame that defines an axis;
• supporting a first panel within the frame;
• moveably supporting a second panel within the frame for sliding movement along the axis between a closed position and an open position relative to the first panel, the second panel including a second face configured to face a first face of the first panel to define an interpanel gap therebetween;
• and
• providing an interpanel coupling system with a first coupling member and a second coupling member, including:
• attaching a first facing member of the first coupling member to the first panel to cover over at least part of the first face, the first coupling member including a first projection that projects from the first facing member into the interpanel gap, the first coupling member being unitary with the first facing member and the first projection being integrally attached;
• attaching a second facing member of the second coupling member to the second panel to cover over at least part of the second face, the second coupling member including a second projection that projects from the second facing member into the interpanel gap, the second coupling member being unitary with the second facing member and the second projection being integrally attached, the first coupling member being constructed from a first material and the second coupling member being constructed from a second material that is different from the first material;
• and
• attaching a seal member to one of the first projection and the second projection, the seal member configured to engage and resiliently deflect against the other of the first projection and the second projection when the second panel is in the closed position, the seal member configured to disengage the other of the first projection and the second projection and resiliently recover toward a neutral position as the second panel moves toward the open position.

A fenestration unit comprising:

• a frame that defines an axis;
• a first panel supported in the frame, the first panel including a first stile;
• a second panel with a second stile moveably supported in the frame for sliding movement along the axis between a closed position and an open position relative to the first panel, the second stile including a second face configured to face a first face of the first stile to define an interpanel gap therebetween;
• an interpanel coupling system with a first coupling member and a second coupling member;
• the first coupling member including a first facing member that is attached to the first panel to cover over at least part of the first face, the first coupling member including a first projection that projects from the first facing member into the interpanel gap, the first coupling member being unitary with the first facing member and the first projection being integrally attached, the first projection providing bending stiffness to the first stile;
• the second coupling member including a second facing member that is attached to the second panel to cover over at least part of the second face, the second coupling member including a second projection that projects from the second facing member into the interpanel gap, the second coupling member being unitary with the second facing member and the second projection being integrally attached, the second projection providing bending stiffness to the second stile;
• the coupling system including a first seal member that is attached to one of the first projection and the second projection, the first seal member configured to engage and resiliently deflect against the other of the first projection and the second projection when the second panel is in the closed position, the first seal member configured to disengage the other of the first projection and the second projection and resiliently recover toward a neutral position as the second panel moves toward the open position;
• the coupling system including a second seal member that is attached to one of the first panel and the second panel and that is configured to resiliently deflect within the interpanel gap as the second panel moves toward the closed position;
• wherein the first coupling member is constructed from a first material and the second coupling member is constructed from a second material that is different from the first material, the first coupling member having higher fracture strength than the second coupling member, and the second coupling member having lower thermal conductivity than the first coupling member.