NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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F2

Part F2 Wet areas and overflow protection

Part F2 Wet areas and overflow protection

Introduction to this Part

This Part is intended to minimise the risk of water from internal wet areas accumulating within a building and causing musty, damp or unhealthy conditions or damaging building elements by corrosion or other degradation. It is also intended to prevent water from internal parts of a building causing damage to other property or parts of a building.

Objectives

The Objective of this Part is to—

  1. safeguard occupants from illness or injury and protect buildings from damage caused by—
    1. internal water from wet areas; and
    2. the accumulation of internal moisture in the building; and
  2. protect other property from damage caused by redirected internal water from wet areas.

Safeguard occupants and protect the building—F2O1(a)

F2O1(a) aims to safeguard occupants in the building from illness or injury, and protect the building from damage, caused by water and moisture from wet areas.

Protect other property from damage—F2O1(b)

F2O1(b) aims to minimise the risk of other property being damaged by water redirected from wet areas.

Functional Statements

A building including internal wet areas is to be constructed in a way that protects people, the building and other property from the adverse effects of internal water from wet areas.

F2F1 Wet areas

F2F1 states that buildings, including their internal wet areas, must be constructed to mitigate the adverse impacts of water. This means that the construction methods, materials, and designs used are to minimise the risks posed by water in these areas. For instance, where necessary wet area floors are to be appropriately graded for effective drainage. Wall and floor junctions are to be sealed to prevent water penetration, thereby protecting the structural integrity of the building and the health of the occupants.

A building is to be constructed to avoid the likelihood of—

  1. the creation of unhealthy or dangerous conditions; and
  2. damage to building elements,

caused by dampness or water overflow from bathrooms, laundries and the like.

F2F2 Overflow from bathrooms and laundries

The development of unhealthy conditions or damage caused by dampness or overflow from bathrooms, laundries and the like, must be prevented. Such problems may arise from showers and bathrooms being incorrectly sealed, allowing water to leak into other parts of the building.

Performance Requirements

NCC Blurbs

Overflow from a bathroom, laundry facility or the like must be prevented from penetrating to adjoining rooms or spaces.

NCC Title
Wet area overflows
NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
Wet area overflows

Overflow from a bathroom, laundry facility or the like must be prevented from penetrating to—

  1. another sole-occupancy unit used for sleeping accommodation; and
  2. a public space,

in a storey below in the same building.

F2P1 Wet area overflows

Water overflows from bathrooms, laundries and the like must be prevented from penetrating downwards—i.e. to a storey below—to either another sole-occupancy unit used for sleeping accommodation or a public space. Such overflows are potentially unhealthy and structurally damaging, and can be disruptive for neighbours.

To protect the structure of the building and to maintain the amenity of the occupants, water must be prevented from penetrating—

  1. behind fittings and linings; and
  2. into concealed spaces,

of sanitary compartments, bathrooms, laundries and the like.

Water – fittings, linings and concealed spaces

The structure of a building and the amenity of its occupants must be protected by preventing water from penetrating behind fittings and linings and into concealed spaces of toilets, bathrooms, laundries and the like.

NCC Blurbs

In laundries, bathrooms or rooms containing shower facilities the floors must be installed in a manner that will prevent accumulation of surface water which could create unhealthy or hazardous conditions.

NCC Title
Prevention of surface water accumulation
NCC State
SA
NCC Variation Type
Insertion
NCC SPTC Current
Prevention of surface water accumulation

Verification Methods

Compliance with F2P1 is verified when the flow rate of the in-built overflow for all vessels in the room is greater than the flow rate of the source filling the vessel.

Applications

F2V1 only applies to bathrooms, laundries and the like in a Class 2 or 3 building or a Class 4 part of a building.

F2V1 Overflow protection

F2V1 allows the use of vessels with built-in overflow for Class 2, 3 or a Class 4 part of a building to provide overflow capacity rather than through the use of a floor waste or other means in bathrooms, laundries or the like.

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements F2P1 and F2P2 are satisfied by complying with F2D2 to F2D4.

(2) Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2G2(3) and A2G4(3) as applicable.

To clarify that the requirements of F2P1 and F2P2 will be satisfied if compliance is achieved with F2D2 to F2D4.

(1) In a Class 2 and 3 building and a Class 4 part of a building, building elements in wet areas must—

  1. be water resistant or waterproof in accordance with Specification 26; and
  2. comply with AS 3740.

SA F2D2 Wet area construction2019: F1.7(a) and (b)

Delete subclause F2D2(1) and insert F2D2(1) as follows:

(1) In a Class 2 and 3 building and a Class 4 part of a building, building elements in wet areas must—

  1. be water resistant or waterproof in accordance with Specification 26, except that—
    1. in any room containing a washing machine, the wall area from finished floor to a minimum of 75 mm above and 75 mm each side of the washing machine tap outlets must be water resistant; and
    2. where a vessel is inset into a bench top in a kitchen, bar area, kitchenette or domestic food and beverage preparation area, the perimeter edges of the vessel must be water resistant for the extent of the vessel; and
    3. penetrations in horizontal surfaces for tap and spout outlets in kitchens, bar areas, kitchenettes or domestic food and beverage preparation areas must be waterproof; and
  2. comply with AS 3740.

(2) In a Class 5, 6, 7, 8 or 9 building, building elements in a bathroom or shower room, a slop hopper or sink compartment, a laundry or sanitary compartment must—

  1. be water resistant or waterproof in accordance with Specification 26; and
  2. comply with AS 3740,

as if they were in a Class 2 or 3 building or a Class 4 part of a building.

To prevent water penetration of roofs which could cause unhealthy and dangerous conditions or loss of amenity for occupants or dampness and deterioration of building elements.

F2D2 Wet area construction

F2D2 requires that certainareas designated as “wet areas” be made impervious to water. This applies to showers, floors and walls adjacent to baths, tubs or laundry troughs, basins, sinks and urinals. The aim is to protect adjacent areas from damage by water splashed from these fixtures.

Adoption of AS 3740 — F2D2(1) and (2)

Class 2 and 3 buildings and Class 4 parts of buildings must be impervious to water in accordance with the design and construction requirements of AS 3740 in the locations listed in Specification 26.

Similar design and location requirements apply for a bathroom, shower room, slop hopper, sink compartment, laundry or sanitary compartment in a Class 5, 6, 7, 8 or 9 building. Specification 26 determines when a building element is required to be waterproof or water resistant, while how to make the building element waterproof or water resistant is determined by AS 3740.

The defined terms for shower area, vessel, waterproof, water resistant and wet area are located under Schedule 1.

(1) Where a slab or stall type urinal is installed—

  1. the floor surface of the room containing the urinal must be an impervious material; and
    1. where no step is installed, must—
      1. be graded to the urinal channel for a distance of 1.5 m from the urinal channel; and
      2. have the remainder of the floor graded to a floor waste; and
    2. where a step is installed—
      1. the step must have an impervious surface and be graded to the urinal channel; and
      2. the floor behind the step must be graded to a floor waste; and
  2. the junction between the floor surface and the urinal channel must be impervious.

(2) Where a wall hung urinal is installed—

  1. the wall must be surfaced with impervious material extending from the floor to not less than 50 mm above the top of the urinal and not less than 225 mm on each side of the urinal; and
  2. the floor must be surfaced with an impervious material and be graded to a floor waste.

(3) In a room with timber or steel-framed walls and containing a urinal—

  1. the wall must be surfaced with an impervious material extending from the floor to not less than 100 mm above the floor surface; and
  2. the junction of the floor surface and the wall surface must be impervious.

To address the specific risks for rooms that contain urinals.

For rooms containing slab or stall type urinals, the floor surface must be constructed of impervious material. This is a material that prevents the passage of water, such as tiled or sealed concrete. When no step is installed near the urinal, the floor is to be graded in a manner that directs water towards the urinal channel for a distance of 1.5 meters. Beyond this distance, the floor must slope towards a floor waste to allow for effective drainage. If a step is installed, it too must be surfaced with an impervious material and graded towards the urinal channel. In this case, the floor area behind the step is to be graded towards a floor waste. Furthermore, the junction where the floor surface meets the urinal channel must also be impervious to prevent any water seepage.

In the case of wall-hung urinals, additional measures are required. The wall behind the urinal must be surfaced with impervious material extending from the floor to a height of not less than 50 mm above the top of the urinal. This impervious material should also extend at least 225 mm on each side of the urinal. As with slab or stall type urinals, the floor should be impervious and graded to a floor waste to enable efficient drainage.

For rooms with walls that are constructed from timber or steel frames, specific requirements apply. These walls must be surfaced with impervious material extending from the floor to a height of not less than 100 mm above the floor surface. Additionally, it is crucial that the junction between the wall surface and the floor surface is made impervious to eliminate any potential for water infiltration.

NCC Blurbs

(1) A wet area provided with a vessel in accordance with F4D2, F4D4 and F4D5 must have the floor graded to a floor waste to permit drainage of water.

(2) With the exception of a bathroom or laundry located at any level above a sole-occupancy unit or public space in a Class 2 or 3 building or Class 4 part of a building, a floor need not be graded to a floor waste in accordance with (1) if—

  1. all vessels in the wet area are provided with in-built overflow protection or have permanent open trapped connection to the plumbing and drainage system (such as a WC pan); or
  2. the vessel is a clinical hand washing basin in a Class 9c building; or
  3. the floor waste is provided solely for the connection of plumbing fixtures and all vessel in the wet area are provided with in-built overflow protection or have permanent open trapped connection to the plumbing and drainage system (such as a WC pan).

(3) The fall of the floor surface to a floor waste required by (1) or (2) must be in accordance with F2D4(2).

NCC Title
Provision of floor wastes
NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
Provision of floor wastes

(1) In a Class 2 or 3 building or Class 4 part of a building, a bathroom or laundry located at any level above a sole-occupancy unit or public space must have a floor waste.

(2) Where a floor waste is installed—

  1. the minimum continuous fall of a floor plane to the waste must be 1:80; and
  2. the maximum continuous fall of a floor plane to the waste must be 1:50.

To prevent water penetration to sole-occupancy units and public spaces from overflow within wet areas.

F2D4 Floor wastes

Floor wastes are to be installed in bathrooms and laundries in Class 2 and Class 3 buildings and Class 4 parts, where those bathrooms and laundries are above another sole-occupancy unit or public space. F2D4(2) requires that the floor containing these mandatory floor wastes be provided with a fall.

The aims of F2D4(1) are to minimise water overflows from fixtures in the specified rooms:

  • causing costly and possibly dangerous water damage to other sole-occupancy units;
  • creating unhealthy conditions in public spaces in buildings; and
  • disrupting and intruding on neighbours in the unit below.

Further, F2D4(2) requires a fall towards any installed floor waste, even floor wastes not required by F2D4(1), F2D3(1)(a)(b) or any other NCC provision.