A system and method for forming flush joints and improving the shear strength in wallboard panels are provided. The system includes using a clamping mechanism to apply simultaneous opposing pressure against the butt joint area so as to cause the edges of adjacent wallboard panels to align level with the plane of the drywall panels. In certain implementations, the system utilizes an elongated tie strap to interconnect a back support disposed on the back side of the drywall panels with a tensioning device which is disposed on the front side of the panels. Adhesive prepackaged in packets can be used to attach the back support to the drywall.