1960s prefab currently wooden cladding on the out side 4x2 walls like stud work and wooden cladding on the inside, on the inside i have used 50mm jab lite to insulate it and finished off with plaster board plaster paint, now looking to do somthing similar cheaply on the out side like king span and render but not sure what to do any ideas greatly appreciated its a three bedroom semi swedish timber frame and timber clad, i have planning for weatherby building systems product but its expensive and they don't want to sell me it?. silicone and polymer modded render over kingspan k5,