Abstract: A set of components for use in constructing a sliding sash window comprises an outer frame member having parallel longitudinally extending channels or recesses therein adapted to accommodate balance spring mechanisms, cover members engageable with the outer frame in order to enclose or partially enclose the channels or recesses at appropriate regions of the assembled frame and to hide the balance spring mechanisms from view, and glazing members engageable with retaiing means formed on the cover members to enable a portion of the outer frame to be fixed glazed without removing the cover members.