Multi-window sash and batten attachment structure

摘要

A multi-window sash including: a frame structure; a plurality of sash units, to each of which a panel is mounted which are connected with each other in a panel width direction, each of the sash units including bilateral vertical frame members, an upper frame member and a lower frame member which constitute a rectangular frame of the sash unit in combination thereof; and a mullion structure connecting adjacent two sash units and including at least a mullion having an expandable structure.