Rigid PVC movement joint applied onto installed gypsum wallboards to provide stress relief and avoidance of cracks in large areas of wallboard. The two wings have perforations to provide the necessary ‘keying’ for the thin-coat plasters and/or joint fillers. Field of Application: Used internally on Gypsum between wallboards to allow the necessary movement and avoid cracking in large areas of wallboard. Thin-coat plasters and/or joint fillers can be applied to provide clean and tidy finishes. A protective polythene film or tape isprovided, which can be removed after plastering or jointing to enable the control joint to be kept clean and free from plastering materials. The control joint is mechanically fixed onto the Gypsum Wallboard using non-corrosive fixings. The control joint can be fixed either vertically or horizontally.