NCC 2019 Volume One Amendment 1
Part F1 Damp and weatherproofing (DtS)

Part F1 Damp and weatherproofing (DtS)

Deemed-to-Satisfy Provisions

F1.0 Deemed-to-Satisfy Provisions

(a)

Performance RequirementFP1.4, for the prevention of the penetration of water through external walls, must be complied with.

Explanatory information

SA F1.0(b)

(b)

Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements FP1.1 to FP1.3 and FP1.5 to FP1.7 are satisfied by complying with F1.1 to F1.13.

(c)

Where a Performance Solution is proposed, the relevant Performance Requirements must be determined in accordance with A2.2(3) and A2.4(3) as applicable.

Intent

To clarify that the requirements of FP1.1 to FP1.7 will be satisfied if compliance is achieved with F1.1 to F1.13.

The BCA does not contain any Deemed-to-Satisfy Provisions which can be followed as a means of complying with FP1.4 for water penetration through external walls. However, it is still compulsory to comply with this Performance Requirement.

This approach has not changed from the previous edition of the BCA.

F1.1 Stormwater drainage

Stormwater drainage must comply with AS/NZS 3500.3.

Requires compliance with AS/NZS 3500.3 to achieve compliance with the Performance Requirements.

F1.2 *  *  *  *  *

Blank clause

This clause has deliberately been left blank.

In BCA 90, this provision was performance-based. In subsequent editions of the BCA, the provision is covered by the Performance Requirements. F1.2 has been left blank rather than renumber subsequent clauses.

F1.3 *  *  *  *  *

Blank clause

This clause has deliberately been left blank.

In BCA 90, this provision was performance-based. In subsequent editions of the BCA, the provision is covered by the Performance Requirements. F1.3 has been left blank rather than renumber subsequent clauses.

F1.4 External above ground membranes

Waterproofing membranes for external above ground use must comply with AS 4654.1 and AS 4654.2.

External above ground membranes to comply with AS 4654 Parts 1 and 2

F1.4 references the Standard for waterproofing membranes for external above ground use.

F1.5 Roof coverings

A roof must be covered with—

(a)

concrete roofing tiles complying with AS 2049 and fixed, except in cyclonic areas, in accordance with AS 2050, as appropriate; or

(b)

terracotta roofing tiles complying with AS 2049 and fixed, except in cyclonic areas, in accordance with AS 2050; or

(c)

cellulose cement corrugated sheeting complying with AS/NZS 2908.1 and installed in accordance with AS/NZS 1562.2; or

(d)

metal sheet roofing complying with AS 1562.1; or

(e)

plastic sheet roofing designed and installed in accordance with AS/NZS 4256.1, AS/NZS 4256.2, AS/NZS 4256.3, AS/NZS 4256.5 and AS/NZS 1562.3; or

(f)

Terracotta, fibre-cement and timber slates and shingles designed and installed in accordance with AS 4597, except in cyclonic areas.

Intent

To prevent water penetration of roofs which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.
Roofing materials and fixing methods

F1.5 contains reference to Australian Standards and other reference documents for a range of roofing materials and fixing methods suitable for the prevention of water penetration.

Concrete and terracotta tiles — cyclonic areas

F1.5(a) and (b), with regard to the use of concrete and terracotta roofing tiles, are not applicable to cyclonic areas, because the AS 2050 fixing details are inadequate for use in such areas. Accordingly, fixing in cyclonic areas must be approved by the appropriate authority.

F1.6 Sarking

Sarking-type material used for weatherproofing of roofs and walls must comply with AS/NZS 4200.1 and AS 4200.2.

Intent

To prevent water penetration of roofs and walls which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.
Sarking to comply with AS/NZS 4200 Parts 1 and AS 4200 Part 2

F1.6 references the Standard for sarking materials where sarking is required for weatherproofing roofs and walls (eg under roof tiles or on walls before weatherboards are fixed).

F1.7 Waterproofing of wet areas in buildings

SA F1.7(a)

(a)

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

(i)

be water resistant or waterproof in accordance with Table F1.7; and

(ii)

comply with AS 3740.

(b)

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

(i)

be water resistant or waterproof in accordance with Table F1.7; and

(ii)

comply with AS 3740,

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

(c)

Where a slab or stall type urinal is installed—

(i)

the floor surface of the room containing the urinal must—

(A)

be an impervious material; and

(B)

where no step is installed—

(aa)

be graded to the urinal channel for a distance of 1.5 m from the urinal channel; and

(bb)

the remainder of the floor be graded to a floor waste; and

(C)

where a step is installed—

(aa)

the step must have an impervious surface and be graded to the urinal channel; and

(bb)

the floor behind the step must be graded to a floor waste; and

(ii)

the junction between the floor surface and the urinal channel must be impervious.

(d)

Where a wall hung urinal is installed—

(i)

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.

(ii)

the floor must be surfaced with impervious material and graded to a floor waste.

(e)

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

(i)

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

(ii)

the junction of the floor surface and the wall surface must be impervious.

Table F1.7 Waterproofing and water-resistance requirements for building elements in wet areas

Vessels or area where the fixture is installed

Floors and horizontal surfaces

Walls

Wall junctions and joints

Wall / floor junctions

Penetrations

Shower area (enclosed and unenclosed)

With hob

Waterproof floor in shower area (including any hob or step-down).

  1. Waterproof all walls in shower area to a height the greater of—
    1. not less than 150 mm above floor substrate; or
    2. not less than 25 mm above maximum retained water level; and
  2. Water resistant walls in shower area to not less than 1800 mm above finished floor level of the shower.

Waterproof wall junctions within shower area.

Waterproof wall / floor junctions within shower area.

Waterproof penetrations in shower area.

With step-down

Without hob or step-down

With preformed shower base

N/A

Water resistant walls in shower area to not less than 1800 mm above finished floor level of the shower.

Waterproof wall junctions within shower area.

Waterproof wall / floor junctions within shower area.

Waterproof penetrations in shower area.

Area outside shower area

For concrete and compressed fibre-cement sheet flooring

Water resistant floor of the room.

N/A

N/A

Waterproof wall / floor junctions.

N/A

For timber floors including particleboard, plywood and other timber based flooring materials

Waterproof floor of the room.

Areas adjacent to baths and spas

For concrete and compressed fibre-cement sheet flooring

Water resistant floor of the room.

  1. 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. Water resistant all exposed surfaces below vessel lip.

Water resistant junctions within 150 mm above a vessel for the extent of the vessel.

Water resistant wall / floor junctions for the extent of the vessel.

Waterproof tap and spout penetrations where they occur in horizontal surfaces.

For timber floors including particleboard, plywood and other timber based flooring materials

Waterproof floor of the room.

Inserted baths and spas

  1. Waterproof shelf area, incorporating waterstop under the bath lip.
  2. No requirement under bath.
  1. Waterproof to not less than 150 mm above lip of bath or spa; and
  2. No requirement under bath.
  1. Waterproof junctions within 150 mm above bath or spa; and
  2. No requirement under bath.

N/A

Waterproof tap and spout penetrations where they occur in horizontal surfaces.

Note: Where a shower is above a bath or spa, use requirements for shower.

Other areas

Walls adjoining other vessel (e.g. sink, basin or laundry tub)

N/A

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.

Waterproof wall junctions where a vessel is fixed to a wall.

N/A

Waterproof tap and spout penetrations where they occur in surfaces required to be waterproof or water resistant.

Laundries and WCs

Water resistantfloor of the room.

N/A

N/A

Water resistant wall / floor junctions.

Waterproof penetration where they occur in surfaces required to be waterproof

Bathrooms and laundries required to provide a floor waste by F1.11.

Waterproof floor of the room.

N/A

N/A

Waterproof wall / floor junctions.

Waterproof penetrations where they occur through the floor.

Explanatory information

Note to Table F1.7 :

N/A means not applicable.

Intent

To prevent water penetration from wet areas in buildings which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.
Wet areas to be impervious to water

F1.7 requires that certain areas 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 — F1.7(a) and (b)

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 Table F1.7.

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. Table F1.7 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 3.

F1.8 *  *  *  *  *

Blank clause

This clause has deliberately been left blank.

In BCA 90, this provision was performance-based. In subsequent editions of the BCA, the provision is covered by the Performance Requirements. F1.8 has been left blank rather than renumber subsequent clauses.

F1.9 Damp-proofing

(a)

Except for a building covered by (c), moisture from the ground must be prevented from reaching—

(i)

the lowest floor timbers and the walls above the lowest floor joists; and

(ii)

the walls above the damp-proof course; and

(iii)

the underside of a suspended floor constructed of a material other than timber, and the supporting beams or girders.

SA F1.9(b)

(b)

Where a damp-proof course is provided, it must consist of—

(i)

a material that complies with AS/NZS 2904; or

(ii)

impervious sheet material in accordance with AS 3660.1.

(c)

The following buildings need not comply with (a):

(i)

A Class 7 or 8 building where in the particular case there is no necessity for compliance.

(ii)

A garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes.

Intent

To prevent moisture from the ground penetrating a building where it could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.
Damp must not rise from the ground — F1.9(a)

Damp must be prevented from reaching:

  • a building's lowest floor timbers;
  • suspended concrete floors or other suspended floors;
  • supporting beams or girders; and
  • walls above damp-proof courses.
Damp-proof course — AS/NZS 2904 or AS 3660.1 — F1.9(b)

AS/NZS 2904 and AS 3660.1 are referenced as alternative options for damp-proof course materials and installation details.

Exemptions — F1.9(c)

F1.9(c) contains exemptions to F1.9(a) because the safety level of buildings will not be significantly diminished by moisture from the ground.

F1.9(c)(i) regarding Class 7 and Class 8 buildings refers only to such buildings which, in a particular case, do not exhibit any need for compliance with F1.9. Such buildings must be considered on a case-by-case basis. However, it is the responsibility of a building proponent to satisfy the appropriate authority that the exemption should apply.

F1.10 Damp-proofing of floors on the ground

SA F1.10

If a floor of a room is laid on the ground or on fill, moisture from the ground must be prevented from reaching the upper surface of the floor and adjacent walls by the insertion of a vapour barrier in accordance with AS 2870, except damp-proofing need not be provided if—

(a)

weatherproofing is not required; or

(b)

the floor is the base of a stair, lift or similar shaft which is adequately drained by gravitation or mechanical means.

Intent

To prevent moisture from the ground penetrating a building where it could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.
Damp must not rise from the ground

F1.10 covers floors resting on the ground. The aim is to prevent ground dampness causing:

  • unhealthy and dangerous conditions or loss of amenity for occupants; or
  • dampness and deterioration of building elements (which, in this case, includes surfaces and linings inside the building, such as floor tiles, wall paint and the like).
Vapour barriers — AS 2870

AS 2870 is referenced for acceptable materials and installation details for vapour barriers to stop ground moisture reaching the upper surface of floors and walls.

Exemptions — F1.10(a) and (b)

Exemptions apply to F1.10 where:

  • weatherproofing is not required for Class 7 or Class 8 buildings where there is no necessity for compliance, sheds forming part of a building used for other purposes, and so on (see the Limitations to FP1.4 for a listing of exempted buildings); and
  • the base of a stairway or lift or similar shaft is suitably drained.

Figure F1.10 illustrates a method of installing damp-proofing in subfloor structures.

Figure F1.10 Installation of DPC in subfloor structures
guide_F110_2010.svg

F1.11 Provision of floor wastes

SA F1.11

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)

a floor waste; and

(b)

the floor graded to the floor waste to permit drainage of water.

Intent

To prevent water from any bathroom or laundry in Class 2 and Class 3 buildings or Class 4 parts from penetrating any sole-occupancy unit or public space, which is in a level below, which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.

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.

The aims of this requirement 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.

F1.12 Subfloor ventilation

(a)

Subfloor spaces must—

(i)

be provided with openings in external walls and internal subfloor walls in accordance with Table F1.12 for the climatic zones given in Figure F1.12; and

(ii)

have clearance between the ground surface and the underside of the lowest horizontal member in the subfloor in accordance with Table F1.12.

Table F1.12 Subfloor openings and ground clearance

Climatic zone (see Figure F1.12 )

Minimum aggregate subfloor ventilation openings without a membrane (mm 2 /m of wall)

Minimum aggregate subfloor ventilation openings having the ground sealed with an impervious membrane (mm 2 /m of wall)

Minimum ground clearance height where termite inspection or management system is not required (mm)

Minimum ground clearance height where termite inspection is required (mm) Note 1

A

2000

1000

150

400

B

4000

2000

150

400

C

6000

3000

150

400

Notes to Table F1.12

Notes to Table F1.12 :

  1. 400 mm clearance required only where termite management systems are installed that need to be inspected (see B1.4).
  2. On sloping sites, the 400 mm clearance required by (1) may be reduced to 150 mm within 2 m of external walls.
  3. In situations where openings in external walls and internal subfloor walls are not able to be provided, additional measures must be provided to ensure that the overall level of ventilation of the subfloor space is maintained. This may include measures similar to those in F1.12(e) i.e. providing durability class timbers, or having the ground sealed in the subfloor space with an impervious membrane.
Figure F1.12 Climatic zones based on relative humidity
v1_F112_2012.svg

Note to Figure F1.12: The season with the highest relative humidity is used. Generally this will be July for southern Australia and January for northern Australia.

(b)

In addition to (a), a subfloor space must—

(i)

be cleared of all building debris and vegetation; and

(ii)

have the ground beneath the suspended floor graded to prevent surface water ponding under the building; and

(iii)

contain no dead air spaces; and

(iv)

have openings evenly spaced as far as practicable; and

(v)

have openings placed not more than 600 mm in from corners.

(c)

In double leaf masonry walls, openings specified in (a) must be provided in both leaves of the masonry, with openings being aligned to allow an unobstructed flow of air.

(d)

Openings in internal subfloor walls specified in (a) must have an unobstructed area equivalent to that required for the adjacent external openings.

(e)

Where the ground or subfloor space is excessively damp or subject to frequent flooding, in addition to the requirements of (a) to (d)

(i)

the subfloor ventilation required in (a) must be increased by 50%; or

(ii)

the ground within the subfloor space must be sealed with an impervious membrane; or

(iii)

subfloor framing must be—

(A)

where above ground, above-ground durability Class 1 or 2 timbers or H3 preservative treated timbers in accordance with AS 1684.2, AS 1684.3 or AS 1684.4; or

(B)

where in ground, in-ground durability Class 1 or 2 timbers or H5 preservative treated timbers in accordance with AS 1684.2, AS 1684.3 or AS 1684.4; or

(C)

steel in accordance with NASH Standard 'Residential and Low-Rise Steel Framing' Part 2.

Intent

To prevent rising dampness which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.

Subfloor ventilation is cross ventilation of the subfloor space between the underside of the floor and ground surface under the lowest suspended floor of a building.

Ground moisture rising into or entering the subfloor space can create a damp environment which encourages timber rot, fungus growth and the potential for termite activity. Subfloor ventilation increases air flow, reducing any damaging water vapour in the subfloor space.

Factors that can affect achieving satisfactory levels of subfloor ventilation include height above ground, prevailing breezes (air transfer), differential temperature and humidity between the subfloor and the external environment and good building practice.

The amount of subfloor ventilation required for a building is related to the relative humidity likely to be encountered in that location. For the purposes of the Deemed-to-Satisfy Provisions, Australia has been divided into three broad climatic zones based on the prevailing relative humidity.

The climatic zones were determined by analysis of the average relative humidity at 9 am and 3 pm in January and July. The season with the highest relative humidity is used. Generally this is July for southern Australia and January for northern Australia. The climatic zone limits are described in Figure F1.12.

Table F1.12 specifies the minimum amount of subfloor ventilation openings and height of subfloor framing members above ground level for the three climatic zones illustrated in Figure F1.12. The table allows subfloor ventilation rates to be halved if the ground within the subfloor space is sealed by an impervious membrane because humidity levels in the space will not be affected by moisture from the soil.

F1.12(e) specifies additional requirements for preventing deterioration of subfloor members where the ground or sub-floor space is excessively damp, as would occur in areas with high water tables, poor drainage or in areas frequently affected by flooding or water inundation.

F1.13 Glazed assemblies

(a)

Subject to (b) and (c), the following glazed assemblies in an external wall, must comply with AS 2047 requirements for resistance to water penetration:

(i)

Windows.

(ii)

Sliding and swinging glazed doors with a frame, including french and bi-fold doors with a frame.

(iii)

Adjustable louvres.

(iv)

Shopfronts.

(v)

Window walls with one piece framing.

(b)

The following buildings need not comply with (a):

(i)

A Class 7 or 8 building where in the particular case there is no necessity for compliance.

(ii)

A garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes, except where the construction of the garage, tool shed, sanitary compartment or the like contributes to the weatherproofing of the other part of the building.

(c)

The following glazed assemblies need not comply with (a):

(i)

All glazed assemblies not in an external wall.

(ii)

Revolving doors.

(iii)

Fixed louvres.

(iv)

Skylights, roof lights and windows in other than the vertical plane.

(v)

Sliding and swinging glazed doors without a frame.

(vi)

Windows constructed on site and architectural one-off windows, which are not design tested in accordance with AS 2047.

(vii)

Second-hand windows, re-used windows and recycled windows.

(viii)

Heritage windows.

Intent

To prevent water penetration of windows which could cause:

  1. unhealthy and dangerous conditions or loss of amenity for occupants; or
  2. dampness and deterioration of building elements.

F1.13 requires windows, etc to comply with the AS 2047 requirements for resistance to water penetration. The provision does not apply to:

  • some Class 7 and 8 buildings;
  • garages, tool sheds, sanitary compartments and the like forming part of a building used for other purposes; and
  • open spectator stands and open-deck carparks.

The exemptions are consistent with limitations in FP1.4 (see FP1.4).