Newcastle homes take salt from two directions. Anything east of the highway gets airborne salt off the ocean, which sits on render and Colorbond and holds moisture against the surface. The older suburbs inland pick up more organic growth instead, because the tree cover keeps walls shaded and damp.
The terrace and workers cottage stock through Cooks Hill, Hamilton and Islington needs a gentler approach than newer builds. Painted weatherboard, lime mortar and original brickwork all suffer under high pressure, so most of that work is soft washing rather than blasting.