NCC 2022 Volume Two - Building Code of Australia Class 1 and 10 buildings
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H2

Part H2 Damp and weatherproofing

Part H2 Damp and weatherproofing

Introduction to this Part

This Part focuses on reducing the risk of illness or injury as a result of the effects of moisture on a building, including surface water, weather and waste water discharge. It also includes requirements to prevent waste water discharge from damaging other property adjoining the site.

Objectives

The Objective is to—

  1. safeguard occupants from illness or injury and protect the building from damage caused by—
    1. surface water; and
    2. external water entering a building; and
    3. the accumulation of internal moisture in a building; and
    4. discharge of swimming pool waste water; and
    5. rising damp; and
  2. protect other property from damage caused by—
    1. redirected surface water; and
    2. the discharge of swimming pool waste 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 from the outside and moisture rising from the ground.

Limitations

H2F2 does not apply to a Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.

Adequate means for the disposal of swimming pool water and drainage is to be provided to a swimming pool.

Performance Requirements

(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.

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

(3) 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.

Limitations

H2P1(2) does not apply to a Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.

A roof and external wall (including openings around windows and doors) must prevent the penetration of water that could cause—

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

Limitations

H2P2(a) does not apply to a Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.

NCC Blurbs

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

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

(2) Barriers installed beneath slab on ground construction for the purposes of (1) must have a high resistance to damage during construction.

Limitations

NSW H2P3 does not apply to a Class 10 building where in the particular case there is no necessity for compliance.

Explanatory information

The intent of requiring the barrier to have a high resistance to damage during construction is to increase the barrier’s ability to resist punctures during construction. By being less susceptible to puncturing, the barrier will provide increased protection against moisture containing dissolved salts from coming into contact with the concrete slab.

NCC Title

Rising damp

NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
Rising damp
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. unhealthy or dangerous conditions, or loss of amenity for occupants; and
  2. undue dampness or deterioration of building elements.

Limitations

H2P3 does not apply to a Class 10 building where in the particular case there is no necessity for compliance.

NCC Title

Drainage from swimming pools

NCC State
NT
NCC Variation Type
Deletion
NCC SPTC Current
Drainage from swimming pools

A swimming pool must have adequate means of draining the pool in a manner which will not—

  1. cause illness to people; or
  2. affect other property.

Notes

The NCC Volume Two and the ABCB Housing Provisions do not contain any Deemed-to-Satisfy Provisions for this Performance Requirement.

Verification Methods

(1) Compliance with H2P2 for weatherproofing of an external wall is verified when—

  1. a prototype passes the procedure described in (2); and
  2. the external wall—
    1. has a risk score of 20 or less, when the sum of all risk factor scores are determined in accordance with Table H2V1a; and
    2. is not subjected to an ultimate limit state wind pressure of more than 2.5 kPa; and
    3. includes only windows that comply with AS 2047.

(2) The test procedure referred to in (1)(a) must be as follows:

  1. The test specimen is in accordance with the requirements of (3).
  2. The test procedure is in accordance with the requirements of (4) and (5) as appropriate.
  3. The test specimen does not fail the criteria in (6).
  4. The test is recorded in accordance with the requirements of (7).

(3) Test specimen: The test specimen must incorporate—

  1. representative samples of openings and joints, including—
    1. vertical and horizontal control joints; and
    2. wall junctions; and
    3. windows or doors; and
    4. electrical boxes; and
    5. balcony drainage and parapet flashings; and
    6. footer and header termination systems; and
  2. for a cavity wall—
    1. a transparent material for a proportion of the internal wall lining (to provide an unobstructed view of the external wall cladding) with sufficient structural capability and similar air tightness to resist the applied wind pressures; and
    2. a 15 mm diameter hole in the internal wall lining below a window.

(4) The test procedure for a direct fix cladding wall or unique wall must be as follows:

  1. Apply 100% positive and negative serviceability wind pressures to the external face of the test specimen for a period of not less than 1 minute each.
  2. Apply static pressure of either 300 Pa or 30% serviceability wind pressure, whichever is higher, in accordance with the water penetration test procedure at clause 8.5.2 of AS/NZS 4284.
  3. Apply cyclic pressure in accordance with—
    1. the three stages of Table H2V1b; and
    2. the water penetration test procedure at clause 8.6.2 of AS/NZS 4284.

(5) The test procedure for a cavity wall must be as follows:

  1. Apply 100% positive and negative serviceability wind pressures to the external face of the test specimen for a period of not less than 1 minute each.
  2. Apply static pressure of either 300 Pa or 30% serviceability wind pressure, whichever is higher, in accordance with the water penetration test procedure at clause 8.5.2 of AS/NZS 4284.
  3. Apply cyclic pressure in accordance with—
    1. stage 3 of Table H2V1b; and
    2. the water penetration test procedure at clause 8.6.2 of AS/NZS 4284.
  4. To simulate the failure of the primary weather-defence or sealing, the following procedure must be applied to the test specimen:
    1. Insert 6 mm diameter holes through the external face of the cavity wall in all places specified below:
      1. Wall/window or wall/door junctions at ¾ height.
      2. Immediately above the head flashing.
      3. Through external sealing of the horizontal and vertical joints.
      4. Above any other penetration detail not covered by (A) to (C).
    2. Repeat the static and cyclic pressure tests of (b) and (c).
    3. Within 30 minutes of the completion of (ii), remove the internal lining of the cavity wall and check for compliance with (6).
    4. With the internal lining removed, apply a final static pressure test at 50 Pa for a period of 15 minutes.

(6) Compliance:

  1. A direct fix cladding wall and unique wall are verified for compliance with H2P2 if there is no presence of water on the inside surface of the facade.
  2. A cavity wall is verified for compliance with H2P2 if there is no presence of water on the removed surface of the cavity, except that during the simulation of the failure of the primary weather-defence or sealing, water may—
    1. transfer to the removed surface of the cavity due to the introduced defects (6 mm holes); and
    2. contact, but not pool on, battens and other cavity surfaces.

(7) Test report — The test report must include the following information:

  1. Name and address of the person supervising the test.
  2. Test report number.
  3. Date of the test.
  4. Cladding manufacturer’s name and address.
  5. Construction details of the test specimen, including a description, and drawings and details of the components, showing modifications, if any.
  6. Test sequence with the pressures used in all tests.
  7. For each of the static and cyclic pressure tests, full details of all leakages, including position, extent and timing.
Table H2V1a Risk factors and scores
Risk factor Category Risk severity Score
Wind region Region A(0-5) (AS/NZS 1170.2) Low to medium 0
Region B1-2 (AS/NZS 1170.2) Low to medium 0
Region C (AS/NZS 1170.2) High 1
Region D (AS/NZS 1170.2) Very high 2
Number of storeys One storey Low 0
Two storeys in part Medium 1
Two storeys High 2
More than two storeys Very high 4
Roof/wall junctions Roof-to-wall junctions fully protected Low 0
Roof-to-wall junctions partially exposed Medium 1
Roof-to-wall junctions fully exposed High 3
Roof elements finishing within the boundaries formed by the external walls Very high 5
Eaves width Greater than 600 mm for single storey Low 0
451-600 mm for single storey Medium 1
Greater than 600 mm for two storey Medium 1
101-450 mm for single storey High 2
451-600 mm for two storey High 2
Greater than 600 mm for above two storey High 2
0-100 mm for single storey Very high 5
0-450 mm for two storey Very high 5
Less than 600 mm for above two storey Very high 5
Envelope complexity Simple shape with single cladding type Low 0
Complex shape with no more than two cladding types Medium 1
Complex shape with more than two cladding types High 3
As for high risk but with fully exposed roof-to-wall junctions Very high 6
Decks, porches and balconies None Low 0
Timber slat deck or porch at ground level Low 0
Fully covered in plan view by roof Medium 2
Timber slat deck attached at first or second floor level Medium 2
Balcony exposed in plan view at first floor level High 4
Balcony cantilevered at first floor level High 4
Balcony exposed in plan view at second floor level or above Very high 6
Balcony cantilevered at second floor level or above Very high 6
Table Notes
  1. Eaves width is measured horizontally from the external face of any wall cladding to the outer edge of any overhang, including fascia and external gutters.
  2. Barriers to prevent falling and parapets are considered as 0 mm eaves.
Table H2V1b Serviceability wind pressure
Stage number Serviceability wind pressure
1 15% to 30%
2 20% to 40%
3 30% to 60%

Explanatory information

H2V1 contains the same test procedures, compliance criteria and reporting of test results that are contained in F3V1, in NCC Volume One. Consequently the Guide to NCC Volume One contains detailed and supportive explanatory information that is also relevant to H2V1.

Deemed-to-Satisfy Provisions

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements H2P1 to H2P3 are satisfied by complying with H2D2 to H2D8.

(2) Performance RequirementH2P4 must be complied with.

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

Notes

There are no Deemed-to-Satisfy Provisions for H2P4.

Performance RequirementH2P1 is satisfied for drainage if it is designed and constructed in accordance with —

  1. AS/NZS 3500.3; or
  2. provided the stormwater drainage system otherwise complies with (a), Part 3.3 of the ABCB Housing Provisions for drainage of—
    1. roofs in areas subject to 5 minute duration rainfall intensities of not more than 255 mm per hour over an annual exceedance probability of 5% (as per Table 7.4.3d of the ABCB Housing Provisions) where a drainage system is required; and
    2. sub-soil areas where excessive soil moisture problems may occur; and
    3. land adjoining and under buildings.

Explanatory information

  • The NCC does not require the installation of drainage systems. Accordingly these requirements need only be applied when these systems are used.
  • Information on the need for drainage systems may be obtained from the appropriate authority.
  • The legal discharge point from a building site is generally determined by local government authorities.

Performance RequirementH2P3 is satisfied for footings and slabs if they are installed in accordance with H1D4(1)(a) or (b).

(1) H2D4(2)—

  1. applies to every external wall (including the junction between the wall and any window or door) of a Class 1 building; and
  2. does not apply to any Class 10 building except where its construction contributes to the weatherproofing of the Class 1 building.

(2) Performance RequirementsH2P2 and H2P3 are satisfied for weatherproofing of masonry if it is carried out in accordance with the appropriate provisions of one of the following:

  1. AS 3700.
  2. AS 4773.1 and AS 4773.2.
  3. Part 5.7 of the ABCB Housing Provisions provided masonry walls are constructed in accordance with H1D5 and the requirements of Part 5.7.

SA H2D4 Masonry2019: 3.3.4

Delete subclause H2D4(2) and insert H2D4(2) as follows:

(2) Performance RequirementsH2P2 and SA H2P3 are satisfied for weatherproofing of masonry if it is carried out in accordance with the appropriate provisions of—

  1. AS 3700 - Masonry structures; or
  2. AS 4773 - Masonry for small buildings, Parts 1 and 2.

SA H2D4 Masonry2019: 3.3.4

Insert SA subclause H2D4(3) in clause H2D4 as follows:

(3) For the purposes of SA H2D4(2), metals and bitumen-coated metals referred to in clauses 7.2. and 7.3 of AS/NZS 2904 are not acceptable materials for use as damp-proof courses in South Australia.

SA H2D4 Masonry2019: 3.3.4

Insert SA subclause H2D4(4) in clause H2D4 as follows:

(4) In low rainfall intensity areas where the site classification is A, S, M, M-D, H, H1, H2, H-D, H1-D or H2-D in accordance with AS 2870, the height of the damp-proof course may be —

  1. 15 mm above finished paved, concreted or landscaped areas; or
  2. 0 mm if the damp-proof course is protected from the direct effects of the weather by a carport, verandah or the like.

Performance RequirementH2P3 is satisfied for subfloor ventilation if it is in accordance with Part 6.2 of the ABCB Housing Provisions.

Explanatory information

Part 6.2 applies to the subfloor space of all suspended floors of a building or deck, including but not limited to, timber and steel-framed subfloors and suspended concrete slabs.

(1) Performance RequirementH2P1 is satisfied for gutters and downpipes if they are designed and constructed in accordance with one of the following:

  1. Subject to (2), AS/NZS 3500.3.
  2. Subject to (2) and (3), Part 7.4 of the ABCB Housing Provisions.

VIC H2D6 Roof and wall cladding2019: 3.5.1-3.5.5

Delete subclause H2D6(1) and insert H2D6(1) as follows:

(1) Performance RequirementH2P1 is satisfied for gutters and downpipes if they are designed and constructed in accordance with AS/NZS 3500.3.

(2) The requirements of (1) do not apply to the removal of surface water from a storm having an annual exceedance probability of 1% for a Class 10 building where in the particular case there is no necessity for compliance.

(3) Part 7.4 of the ABCB Housing Provisions—

  1. may only be used provided the roof drainage system is connected to a stormwater drainage system that complies with H2D2; and
  2. excludes box gutters.

VIC H2D6 Roof and wall cladding2019: 3.5.1-3.5.5

This subclause been deliberately left blank

(4) Performance RequirementH2P2 is satisfied for roof and wall cladding if it is in accordance with H1D7(2), (3), (4) or (5) as appropriate.

Performance RequirementH2P2 is satisfied for weatherproofing for glazing if it is in accordance with H1D8(1).

Explanatory information

When satisfying Performance Requirement H2P2, H1D8(1) only references AS 2047 for windows. If AS 1288 is used for glazing in an external wall, it is still necessary to satisfy H2P2.

(1) Performance RequirementH2P2 is satisfied for the design and construction of external waterproofing for roofing systems on flat roofs, roof terraces, balconies and terraces and other similar horizontal surfaces located above internal spaces of a building provided—

  1. membranes used in the external waterproofing system comply with AS 4654.1; and
  2. the design and installation of the external waterproofing system is in accordance with AS 4654.2.

(2) The requirements of (1) apply to—

  1. roofing systems other than those complying with H1D7(2) and (3); and
  2. terraces, balconies and the like other than—
    1. a concrete slab that has a minimum step-down of 50 mm below the internal floor level; or
    2. a suspended concrete slab—
      1. where the subfloor space is not used for habitable or non-habitable purposes; and
      2. that has a minimum step-down of 50 mm below the internal floor level; or
    3. spaced decking in conjunction with framing members that are suitable for external use.

Explanatory information

The design of occupiable roof-top spaces, decks, balconies, particularly where located over internal spaces of a building, can be susceptible to potential for water ingress into a building and causing damage. Therefore, careful consideration should be given to the design, construction and the materials used to minimise the potential for water ingress to spaces below.

H2D8 prescribes external waterproofing requirements for buildings, and references AS 4654 Parts 1 and 2 that provide solutions for liquid and/or sheet membrane roofing systems on flat roofs, roof terraces, balconies and terraces located over habitable rooms. The term flat roof is commonly used to describe a near flat roof with enough pitch to provide drainage for rainwater.

AS 4654.1 sets out the requirements for materials forming part of a waterproofing system and AS 4654.2 sets out design and construction/installation requirements.

A Performance Solution in accordance with A2G2 would need to be provided for other types of external waterproofing materials and designs.