what about my idea of normal king span with stud work ,expanded metal lath and either normal sand cement render or mey be with an addative or would i have to use to the polyermer modded render
cheers ben
You could use metal mesh -the recommended would be stainless steel rib lath , rather than eml. Then you could render, and an SBR added would give you some flex. You could use galv eml, which is cheaper, but will eventually (who knows how long?) rust, and you will have to paint it at least twice in ten years.
The advantage of the other systems mentioned is the mesh is fibreglass, so it is a bit more flexible, won't rust, and a tight coat will cover it it is also cheaper than metal lath and easier to use. The final coat will be coloured, so no painting. The over all thickness will be less too.