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
F1O1
Objective
2019: FO1
The Objective of this Part is to—
- safeguard occupants from illness or injury and protect the building from damage caused by—
- surface water; and
- external moisture entering a building; and
- the accumulation of internal moisture in a building; and
- protect other property from damage caused by redirected surface water.
Functional Statements
F1F1
Protection from redirected surface water
2019: FF1.1
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.
F1F2
Resistance to rain, surface water and ground water
2019: FF1.2
A building is to be constructed to provide resistance to moisture penetrating from the outside, including rising from the ground.
Performance Requirements
F1P1
Managing rainwater impact on adjoining properties
2019: FP1.1
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.
F1P2
Preventing rainwater from entering buildings
2019: FP1.2
Surface water, resulting from a storm having an annual exceedance probability of 1%, must not enter the building.
Limitations
F1P2 does not apply to—
- a Class 7 or 8 building where in the particular case there is no necessity for compliance; or
- a garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes; or
- an open spectator stand or open-deck carpark.
F1P3
Rainwater drainage systems
2019: FP1.3
A drainage system for the disposal of surface water resulting from a storm having an annual exceedance probability of—
- 5% must—
- convey surface water to an appropriate outfall; and
- avoid surface water damaging the building; and
- 1% must avoid the entry of surface water into a building.
F1P4
Rising damp
2019: FP1.5
- undue dampness or deterioration of building elements; and
- unhealthy or dangerous conditions, or loss of amenity for occupants.
- high resistance to moisture penetration; and
- high resistance to damage during construction; and
- high resistance to degradation by dissolved salts.
Rising damp
Moisture from the ground must be prevented from causing—
- undue dampness or deterioration of building elements; and
- unhealthy or dangerous conditions, or loss of amenity for occupants.
Limitations
F1P4 does not apply to—
- a Class 7 or 8 building where in the particular case there is no necessity for compliance; or
- a garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes; or
- an open spectator stand or open-deck carpark.
Deemed-to-Satisfy Provisions
F1D1
Deemed-to-Satisfy Provisions
2019: F1.0
SA F1D1 Deemed-to-Satisfy Provisions2019: F1.0
F1D2
Application of Part
New for 2022
F1D3
Stormwater drainage
2019: F1.1
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.
F1D4
Exposed joints
New for 2022
Exposed joints in the drainage surface on a roof, balcony, podium or similar horizontal surface part of a building must—
- be protected in accordance with Section 2.9 of AS 4654.2; and
- 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.
F1D5
External waterproofing membranes
2019: F1.4
A roof, balcony, podium or similar horizontal surface part of a building must be provided with a waterproofing membrane—
- consisting of materials complying with AS 4654.1; and
- designed and installed in accordance with AS 4654.2.
F1D6
Damp-proofing
2019: F1.9
- the lowest floor timbers and the walls above the lowest floor joists; and
- the walls above the damp-proof course; and
- the underside of a suspended floor constructed of a material other than timber, and the supporting beams or girders.
- a material that complies with AS/NZS 2904; or
- impervious sheet material in accordance with AS 3660.1.
SA F1D6 Damp-proofing2019: F1.9
- embossed black polyethylene film meeting the requirements of clause 7.6 of AS/NZS 2904; or
- polyethylene coated aluminium meeting the requirements of clause 7.4 of AS/NZS 2904; or
- 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.
- A Class 7 or 8 building where in the particular case there is no necessity for compliance.
- A garage, tool shed, sanitary compartment, or the like, forming part of a building used for other purposes.
- An open spectator stand or open-deck carpark.
F1D7
Damp-proofing of floors on the ground
2019: F1.10
Damp-proofing of floors on the ground
F1D8
Subfloor ventilation
2019: F1.12
- 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
- have clearance between the ground surface and the underside of the lowest horizontal member in the subfloor in accordance with Table F1D8.
- be cleared of all building debris and vegetation; and
- have the ground beneath the suspended floor graded to prevent surface water ponding under the building; and
- contain no dead air spaces; and
- have openings evenly spaced as far as practicable; and
- have openings placed not more than 600 mm in from corners.
- the subfloor ventilation required in (1) must be increased by 50%; or
- the ground within the subfloor space must be sealed with an impervious membrane; or
- subfloor framing must be—
- 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
- 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
- steel in accordance with NASH Standard ‘Residential and Low-Rise Steel Framing’ Part 2.
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
- 400 mm clearance required only where termite management systems are installed that need to be inspected (see B1D4).
- On sloping sites, the 400 mm clearance required by (1) may be reduced to 150 mm within 2 m of external walls.
- 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.
- 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 Notes
The season with the highest relative humidity is used. Generally this will be July for southern Australia and January for northern Australia.