NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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26

Specification 26 Waterproofing and water-resistance requirements for building elements in wet areas

Specification 26 Waterproofing and water-resistance requirements for building elements in wet areas

This Specification sets out requirements for building elements in wet areas that are required to be—

  1. water resistant; or
  2. waterproof.

 

This specification aims to outline the requirements for building elements in wet areas, specifically focusing on their need to be either water-resistant or waterproof. The installation instructions are provided in AS 3740.

(1) The requirements of this Specification apply to—

  1. shower areas (enclosed and unenclosed); and
  2. areas outside a shower area; and
  3. areas adjacent to baths and spas; and
  4. other areas as set out in clause S26C6.

(2) Where a shower is above a bath or spa, use requirements for a shower.

 

S26C2 delineates the areas where this specification applies, which includes both enclosed and unenclosed shower areas, areas outside shower spaces, areas adjacent to baths and spas and other areas such as WCs and laundries. When a shower is positioned above a bath or spa, the shower's requirements take precedence.

(1) For a shower area with a hob, step-down or level threshold, the following applies:

  1. The floor of the shower area must be waterproof, including any hob or step-down; and
  2. The walls of the shower area must be waterproof not less than 1800 mm above the floor substrate.
  3. Wall junctions and joints within the shower area must be waterproof.
  4. Wall/floor junctions within the shower area must be waterproof.
  5. Penetrations within the shower area must be waterproof.

(2) A shower with a preformed shower base must also comply with the requirements of (1), except for (a) which is not applicable.

 

S26C3 sets detailed requirements for enclosed and unenclosed shower areas. If a shower area has a hob, step-down, or level threshold, the floor, walls, wall junctions and penetrations within this area must all be waterproof. Notably, the walls need to be waterproof up to a minimum height of 1800 mm above the floor substrate. Preformed shower bases must also comply with S26C3(1), except for the requirements of S26C3(1)(a).

(1) For concrete, compressed fibre-cement and fibre-cement sheet flooring, the floor of the room must be water resistant.

(2) For timber floors including particleboard, plywood and other timber based flooring materials, the floor of the room must be waterproof.

(3) Wall/floor junctions must be waterproof.

 

For areas outside the shower, the level of water resistance or waterproofing required is dictated by the type of flooring material. Concrete and fibre-cement (including compressed fibre cement) floors should be water-resistant, while timber-based floors must be waterproof. Additionally, where the wall meets the floor, the junction must be waterproofed.

(1) For areas adjacent to a bath and spa, the following applies:

  1. For concrete, compressed fibre-cement and fibre-cement sheet flooring, the floor of the room must be water resistant.
  2. For timber floors including particleboard, plywood and other timber based flooring materials, the floor of the room must be waterproof.
  3. Tap and spout penetrations must be waterproof where they occur in horizontal surfaces.

(2) For areas adjacent to a non-freestanding bath and spa, the following applies:

  1. Walls must be water resistant—
    1. to a height of not less than 150 mm above the vessel, for the extent of the vessel, where the vessel is within 75 mm of a wall; and
    2. at all exposed surfaces below vessel lip.
  2. Wall junctions and joints must be water resistant within 150 mm above a vessel for the extent of the vessel.
  3. Wall/floor junctions must be waterproof for the extent of the vessel.

(3) For inserted baths and spas, the following applies:

  1. For floors and horizontal surfaces:
    1. Any shelf area adjoining the bath or spa must be waterproof and include a waterstop under the vessel lip.
    2. There are no requirements for the floor under a bath or spa.
  2. For walls:
    1. Waterproof to not less than 150 mm above the lip of a bath or spa.
    2. There are no requirements for walls beneath the lip of a bath or spa.
  3. For wall junctions and joints:
    1. Waterproof junctions within 150 mm of a bath or spa.
    2. There are no requirements for junctions and joints in walls beneath the lip of a bath or spa.
  4. Tap and spout penetrations must be waterproof where they occur in horizontal surfaces.

 

S26C5 elaborates on the requirements for areas next to baths and spas. Similar to the previous provision, the type of flooring dictates whether the area should be water-resistant or waterproof. There are also specific criteria for wall resistance depending on whether the bath or spa is freestanding, inserted, or otherwise, as well as requirements for waterproofing tap and spout penetrations in horizontal surfaces.

(1) For walls adjoining other types of vessels (e.g. sink, basin or laundry tub), the following applies:

  1. Walls must be water resistant to a height of not less than 150 mm above the vessel, for the extent of the vessel, where the vessel is within 75 mm of a wall.
  2. Waterproof wall junctions where a vessel is fixed to a wall.
  3. Waterproof tap and spout penetrations where they occur in surfaces required to be waterproof or water resistant.

(2) For laundries and WCs, other than WCs as described in (3), the following applies:

  1. Water resistant floor of the room.
  2. Water resistant wall/floor junctions.
  3. Waterproof penetrations where they occur in surfaces required to be waterproof.

(3) For WCs with a handheld bidet spray installation, the following applies:

  1. Waterproof floor of the room.
  2. Walls must be—
    1. waterproof within a 1500 mm radius from the wall connection of the handheld bidet spray device to a height of not less than 150 mm above the floor substrate; and
    2. water resistant within a 1500 mm radius from the wall connection of the handheld bidet spray device to a height of not less than 1200 mm above the finished floor level of the WC.
  3. Waterproof wall junctions within the WC area within 1500 mm radius from the wall connection of the handheld bidet spray device.
  4. Waterproof wall/floor junctions within the WC area within 1500 mm radius from the wall connection of the handheld bidet spray device.
  5. Waterproof penetrations in WC area.

(4) For bathrooms and laundries required to be provided with a floor waste by F2D4, the following applies:

  1. Waterproof floor of the room.
  2. Waterproof wall/floor junctions.
  3. Waterproof penetrations where they occur through the floor.

 

S26C6 aims to ensure water integrity across a variety of scenarios and building elements. It delineates between water-resistant and waterproof requirements.

S26C6(1) requires walls adjoining sinks, basins, or laundry tubs to be water-resistant to a height of at least 150 mm above the vessel when the vessel is within 75 mm of the wall. Additionally, any wall junctions where a vessel is fixed to a wall must be waterproof, as should any tap and spout penetrations in surfaces designated as water-resistant or waterproof.

S26C6(2) applies to laundries and WCs that don't feature a handheld bidet spray. The room's floor and wall/floor junctions are to be water-resistant. Penetrations in surfaces required to be waterproof must also be waterproof.

Special attention is required for WCs with a handheld bidet spray; the entire floor must be waterproof. Walls within a 1500 mm radius from the wall connection of the bidet spray device must be waterproof up to 150 mm above the floor substrate and water-resistant up to 1200 mm above the finished floor level. Additionally, wall/floor junctions and penetrations within this 1500 mm radius must be waterproof.

Where bathrooms and laundries are required by F2D4 to have a floor waste, the entire floor, as well as wall/floor junctions, must be waterproof. Any penetrations through the floor must also be waterproof.