Curtain wall construction allowing vertical and horizontal expansion

Claim 1

A CURTAIN WALL CONSTRUCTION HAVING VERTICAL COLUMNS OF MULLIONS JOINED TOGETHER WITH HORIZONTAL MEMBERS FOR RETAINING AND SUPPORTING WALL PANELS, COMPRISING; AT LEAST ONE OF THE HORIZONTAL MEMBERS HAVING FRONT AND REAR FLANGES JOINED TOGETHER BY A WEB; AT LEAST ONE OF THE MULLIONS HAVING A RECESS WHICH RECEIVES AN END PORTION OF SAID ONE HORIZONTAL MEMBER AND SLIDABLY ENGAGES SAID FRONT AND BACK FLANGES THEREOF SO THAT THE HORIZONTAL MEMBER IS RESTRAINED FROM FORWARD OR REARWARD MOVEMENT WITH RESPECT TO THE MULLION; SAID HORIZONTAL MEMBER HAVING AN END WHICH IS SPACED FROM SAID MULLION SO AS TO ALLOW FOR EXPANSION OF THE HORIZONTAL MEMBER; SUPPORT MEANS OPERATIVELY AN END WHICH IS SPACED AND SLIDABLY ENGAGING A BOTTOM SIDE OF SAID HORIZONTAL MEMBER WEB AND SUPPORTING SAID END PORTION SO THAT THE HORIZONTAL MEMBER CAN SLIDE ON SAID SUPPORT MEANS WHEN EXPANDING OR CONTRACTING; RESTRAINING MEANS OPERATIVELY CONNECTED TO SAID MULLION AND SLIDABLY ENGAGING A TOP SIDE OF THE HORIZONTALLY MEMBER WEB SO AS TO RESTRAIN UPWARD MOVEMENT OF THE HORIZONTAL MEMBER; SAID MULLION AND AN ADJACENT MULLION IN A COLUMN HAVING THEIR OPPOSED ENDS SPACED FROM ONE ANOTHER SO AS TO ALLOW FOR EXPANSION THEREOF; THE ADJACENT MULLIONS EACH HAVING A FORWARD HOLLOW PORTION, A REAR PORTION, AND A WEB PORTION EXTENDING THEREBETWEEN AND SUBSTANTIALLY CO-EXTENSIVE IN LENGHT THEREWITH, THE HOLLOW PORTION, THE WEB PORTION AND THE REAR PORTION FORMING THE MULLION RECESS OF SAID ONE MULLION AND A SIMILAR RECESS FOR THE ADJACENT MULLION;