I NSTALL AT I ON
Bathroom waterproofing and the BCA Barry Schafer explains what the building code can mean when waterproofing bathrooms.
T
he Building Code of Australia (BCA) has since 1996 has been a performance based code. For bathrooms, which come under the wet area classification in detached dwellings, the relevant performance Clause is F1.7 ‘Waterproofing of wet areas’ in buildings which states: “The following parts of a building must be impervious to water: (a)In any building – the floor surface or substrate in a shower enclosure, or within 1.5 metres measured horizontally from a point vertically below the shower fitting, if there is no enclosure. (b)In a Class 3, 5, 6, 7, 8 or 9 building – the floor surface or substrate in a bathroom or shower room, slop hopper or sink compartment, laundry or sanitary compartment which is used in common by the occupants. (c)In a Class 2 or 3 building or a Class 4 part – the floor of those rooms fitted with a floor waste in accordance with F1.11. (d)The wall surface or substrate – (i) of a shower enclosure, or if the shower is not enclosed, within 1.5 metres and exposed to a shower fitting, to a height of 1.8 metres above the floor; and (ii) immediately adjacent or behind a bath, trough, basin, sink, or similar fixture, to a height not less than 150 mm above the fixture if it is within 75 mm of the wall. (e)The junction between the floor and the wall if the wall and floor are required to be impervious to water. (f) The junction between the wall and fixture if the wall is required to be impervious to water.”
66 | TILE TODAY #91 | www.tiletodaymagazine.com.au
The reference to F1.11 is for the case where flooding from an occupancy above can affect those below. F1.11 Provision of Floor Wastes states: “In a Class 2 or 3 building or Class 4 part, the floor of each bathroom and laundry in a sole-occupancy unit which is located at any level above another sole occupancy unit must be graded to permit drainage to a floor waste.” Compliance to AS 3740 – 2010 (incorporating Amendment No. 1) ‘Waterproofing of domestic wet areas’ is deemed to satisfy the requirements of these BCA Clauses. Any Australian Standard that is referenced in the BCA as a deemed-to-satisfy solution is written to give the minimum requirements to comply with the BCA and in doing so keeps the cost of construction to a minimum. Figure 1 illustrates a shower treatment.
There are some handbooks available which go beyond these minimum requirements. This can cause some confusion within the industry but compliance with AS 3740 meets the minimum required by the BCA. For a shower, the waterproofing and water resistant requirements specified in AS 3740 are depicted in Figure 1. The height of the waterproofing up the walls (the 150mm or 25mm above maximum water level) depends on if there is a step-down in the floor or a hob. Both of these can result in a greater height than the specified 150mm. To determine the maximum water level, one needs to consider the retention height effects of the surface finish and the shower enclosure across the opening. These can often raise the water height by up to 40 mm