These consist of sunken and/or non-sunken areas within the structure such as toilets, bathrooms, internal wet areas, food preparation areas in commercial establishments, laundry areas, service floors, AHU rooms, kitchens and balconies etc. which are exposed to or in contact with domestic water which is being used by the occupants.

Waterproofing in these areas needs to cater to exposure related to the presence of cleaning liquids in water and have to ideally sustain permanent water immersion conditions especially when used in sunken portions.

When used in dry wall systems, they also need higher flexibility and the capability to allow direct installation of tiles with suitable adhesives.