If you have a full bathroom project that requires new tiles, you often find the old walls require plastering. There is a very specific process required to plaster high humidity and water prone areas such as showers, bathrooms, ensuites, laundries and toilets
Wet areas are defined as areas within a building that are supplied with water.
BCA Requirements
The Building Code of Australia requires that wet areas be treated in accordance with Australian Standard AS3740 Waterproofing of Wet Areas within Residential Buildings. Additional requirements may apply in some states.
AS3740 classifies wet areas into Levels of Risk and specifies which walls, floors, junctions and penetrations are to be treated as waterproof or water resistant.
High risk areas are bathrooms and laundries that require a floor waste, and shower areas. Medium risk areas are outside of the shower in bathrooms and adjacent to baths and spas. Low risk areas are laundries and toilets, and other walls adjoining sinks and tubs.