Ok guys, let me start by saying I'm not a plasterer. I am preparing my house for a K Rend/ Weber etc etc finish. My house is a non cavity construction and I have hacked off the defective sand and cement render to the brickwork. I have lined the brickwork with external thermal insulation boards and I am preparing the boards for the render guys. I am fitting the beads, mesh and mesh basecoat and the render guys are going to lay the top coat. My question is should I use 10mm or 15mm beads taking into account I am fitting them to the flat insulation boards. Many thanks in advance of constructive advice.