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

F1

Part F1 Surface water management, rising damp and external waterproofing

Part F1 Surface water management, rising damp and external waterproofing

Introduction to this Part

This Part is intended to minimise the risk of water leaking into or accumulating within a building and causing unhealthy conditions or damaging building elements by corrosion or rot. It is also intended to prevent water redirected away from the building damaging nearby properties.

Objectives

The Objective of this Part is to—

  1. safeguard occupants from illness or injury and protect the building from damage caused by—
    1. surface water; and
    2. external moisture entering a building; and
    3. the accumulation of internal moisture in a building; and
  2. protect other property from damage caused by redirected surface water.

Functional Statements

A building, including any associated sitework, is to be constructed in a way that protects people and other property from the adverse effects of redirected surface water.

A building is to be constructed to provide resistance to moisture penetrating from the outside, including rising from the ground.

Performance Requirements

Surface water, resulting from a storm having an annual exceedance probability of 5% and which is collected or concentrated by a building or sitework, must be disposed of in a way that avoids the likelihood of damage or nuisance to any other property.

Surface water, resulting from a storm having an annual exceedance probability of 1%, must not enter the building.

Limitations

F1P2 does not apply to—

  1. a Class 7 or 8 building where in the particular case there is no necessity for compliance; or
  2. a garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes; or
  3. an open spectator stand or open-deck carpark.

A drainage system for the disposal of surface water resulting from a storm having an annual exceedance probability of—

  1. 5% must—
    1. convey surface water to an appropriate outfall; and
    2. avoid surface water damaging the building; and
  2. 1% must avoid the entry of surface water into a building.
NCC Blurbs

(1) Moisture from the ground must be prevented from causing—

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

(2) Barriers installed to prevent transfer of moisture from the ground must have—

  1. high resistance to moisture penetration; and
  2. high resistance to damage during construction; and
  3. high resistance to degradation by dissolved salts.
NCC Title

Rising damp

NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
Rising damp

Moisture from the ground must be prevented from causing—

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

Limitations

F1P4 does not apply to—

  1. a Class 7 or 8 building where in the particular case there is no necessity for compliance; or
  2. a garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes; or
  3. an open spectator stand or open-deck carpark.

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements F1P1 to F1P4 are satisfied by complying with F1D2 to F1D8.

SA F1D1 Deemed-to-Satisfy Provisions2019: F1.0

Delete subclause F1D1(1) and insert F1D1(1) as follows:

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements F1P1 to F1P3 and SA F1P4 are satisfied by complying with F1D2 to F1D5, F1D6 (1) and (3), SA F1D6(2), SA F1D7 and F1D8.

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

(1) F1D4 and F1D5 do not apply to a roof with a covering complying with F3D2(a) to (d).

(2) F1D3 to F1D5 do not apply to a balcony, podium or similar horizontal surface part of a building—

  1. where the flooring is of timber decking or other perforated flooring; or
  2. which is located directly above ground.

Stormwater drainage must be designed and constructed in accordance with AS/NZS 3500.3.

Explanatory information

Where stormwater drainage does not comply with F1D3, a Performance Solution is to be used to demonstrate compliance with the relevant Performance Requirements.

Exposed joints in the drainage surface on a roof, balcony, podium or similar horizontal surface part of a building must—

  1. be protected in accordance with Section 2.9 of AS 4654.2; and
  2. not be located beneath or run through a planter box, water feature or similar part of the building.

Notes

For the purposes of F1D4, an exposed joint is a construction joint, control joint, expansion joint, contraction joint or movement joint and includes an exposed joint which is directly below a drainage surface.

Explanatory information: Location of exposed joints

To minimise the potential of water ingress, the exposed joint should be located at a ridge or high point of the structural substrate, where possible.

Explanatory information: Exposed joints subject to excessive movement

Where an exposed joint is subject to excessive movement, such as more than 10 mm, additional measures should be considered to ensure protection of the exposed joint. These additional measures may include use of a hob with a minimum height of 50 mm formed within the structural substrate for the full length of both sides of the exposed joint, and the exposed joint protected by a discontinuous membrane in accordance with Section 2.9 of AS 4654.2.

A roof, balcony, podium or similar horizontal surface part of a building must be provided with a waterproofing membrane—

  1. consisting of materials complying with AS 4654.1; and
  2. designed and installed in accordance with AS 4654.2.

(1) Except for a building covered by (3), moisture from the ground must be prevented from reaching—

  1. the lowest floor timbers and the walls above the lowest floor joists; and
  2. the walls above the damp-proof course; and
  3. the underside of a suspended floor constructed of a material other than timber, and the supporting beams or girders.

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

  1. a material that complies with AS/NZS 2904; or
  2. impervious sheet material in accordance with AS 3660.1.

SA F1D6 Damp-proofing2019: F1.9

Delete subclause F1D6(2) and insert F1D6(2) as follows:

(2) Damp-proof courses must exhibit long term resistance to degradation by dissolved salts in groundwater and consist of—

  1. embossed black polyethylene film meeting the requirements of clause 7.6 of AS/NZS 2904; or
  2. polyethylene coated aluminium meeting the requirements of clause 7.4 of AS/NZS 2904; or
  3. bitumen impregnated materials of not less than 2.5 mm thickness, meeting the requirements of clause 7.5 of AS/NZS 2904, when used in walls not higher than 7.8 m above the level of the damp-proof course.

(3) The following buildings need not comply with (1):

  1. A Class 7 or 8 building where in the particular case there is no necessity for compliance.
  2. A garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes.
  3. An open spectator stand or open-deck carpark.
NCC Blurbs

(1) If a floor of a room is laid on the ground or on fill, a damp-proofing membrane complying with Section 5.3.3 of AS 2870 must be installed.

(2) A damp-proofing membrane need not be provided if—

  1. weatherproofing is not required; or
  2. the floor is the base of a stair, lift or similar shaft which is adequately drained by gravitation or mechanical means.
NCC Title

Damp-proofing of floors on the ground

NCC State
SA
NCC Variation Type
Replacement
NCC SPTC Current
Damp-proofing of floors on the ground

(1) 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.

(2) The requirements of (1) do not apply where—

  1. weatherproofing is not required; or
  2. the floor is the base of a stair, lift or similar shaft which is adequately drained by gravitation or mechanical means.

(1) Subfloor spaces must—

  1. be provided with openings in external walls and internal subfloor walls in accordance with Table F1D8 for the climatic zones given in Figure F1D8; and
  2. have clearance between the ground surface and the underside of the lowest horizontal member in the subfloor in accordance with Table F1D8.

(2) In addition to (1), a subfloor space must—

  1. be cleared of all building debris and vegetation; and
  2. have the ground beneath the suspended floor graded to prevent surface water ponding under the building; and
  3. contain no dead air spaces; and
  4. have openings evenly spaced as far as practicable; and
  5. have openings placed not more than 600 mm in from corners.

(3) In double leaf masonry walls, openings specified in (1) must be provided in both leaves of the masonry, with openings being aligned to allow an unobstructed flow of air.

(4) Openings in internal subfloor walls specified in (1) must have an unobstructed area equivalent to that required for the adjacent external openings.

(5) Where the ground or subfloor space is excessively damp or subject to frequent flooding, in addition to the requirements of (1) to (4)—

  1. the subfloor ventilation required in (1) must be increased by 50%; or
  2. the ground within the subfloor space must be sealed with an impervious membrane; or
  3. subfloor framing must be—
    1. 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
    2. 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
    3. steel in accordance with NASH Standard ‘Residential and Low-Rise Steel Framing’ Part 2.
Table F1D8 Subfloor openings and ground clearance
Climatic zone (see Figure F1D8) Minimum aggregate subfloor ventilation openings without a membrane (mm2/m of wall) Minimum aggregate subfloor ventilation openings having the ground sealed with an impervious membrane (mm2/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
Table Notes
  1. 400 mm clearance required only where termite management systems are installed that need to be inspected (see B1D4).
  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.
  4. Additional measures referred to in (3) may include measures similar to those in F1D8(5), such as providing durability class timbers, or having the ground sealed in the subfloor space with an impervious membrane.
Figure F1D8 Climatic zones based on relative humidity
image-F1D8-climatic-zones-based-on-relative-humidity.svg
Figure Notes

The season with the highest relative humidity is used. Generally this will be July for southern Australia and January for northern Australia.