Where should I put expansion joints when using render or stucco?

The first expansion joint should be positioned in line with the substrate expansion joints, typically every 6 linear metres. In the Code of Practice for external render, expansion joints are also put to one side of window and door openings: stress cracking tends to occur here, making it the weakest part of the render matrix. Be sure not to render an unbroken area larger than 18 square metres.