NCC 2022 Volume Two - Building Code of Australia Class 1 and 10 buildings
H1
Part H1 Structure
Part H1 Structure
Introduction to this Part
This Part focuses on safeguarding people from injury caused by structural failure, loss of amenity caused by structural behaviour (deflections, creep, vibration, settlement and the like), protection of other property from physical damage caused by structural failure and safeguarding people from injury that may be caused by failure of, or impact with, glazing.
Objectives
H1O1
Objective
2019: O2.1
The Objective is to—
safeguard people from injury caused by structural failure; and
safeguard people from loss of amenity caused by structural behaviour; and
protect other property from physical damage caused by structural failure; and
safeguard people from injury that may be caused by failure of, or impact with, glazing.
(1) By resisting the actions to which it may reasonably be expected to be subjected, a building or structure, during construction and use, with appropriate degrees of reliability, must—
perform adequately under all reasonably expected design actions; and
withstand extreme or frequently repeated design actions; and
be designed to sustain local damage, with the structural system as a remaining stable and not being damaged to an extent disproportionate to the original local damage; and
(3) The structural resistance of materials and forms of construction must be determined using five percentile characteristic material properties with appropriate allowance for—
known construction activities; and
type of material; and
characteristics of the site; and
the degree of accuracy inherent in the methods used to assess the structural behaviour; and
action effects arising from the differential settlement of foundations, and from restrained dimensional changes due to temperature, moisture, shrinkage, creep and similar effects.
(4) Glass installations that are at risk of being subjected to human impact must have glazing that—
if broken on impact, will break in a way that is not likely to cause injury to people; and
resists a reasonably foreseeable human impact without breaking; and
is protected or marked in a way that will reduce the likelihood of human impact.
Building work in designated flood hazard areas is regulated by the Building Act 1975 and Development Code 3.5 - Construction of buildings in flood hazard areas.
NCC ID
idm5339
NCC Title
Buildings in flood areas
NCC State
SA
NCC Variation Type
Deletion
NCC SPTC Current
Buildings in flood areas
NCC Notice
Part H1 does not apply in South Australia.
NCC ID
idm5340
(1) A building in a flood hazard area must be designed and constructed, to the degree necessary, to resist flotation, collapse or significant permanent movement resulting from the action of hydrostatic, hydrodynamic, erosion and scour, wind and other actions during the defined flood event.
(2) The actions and requirements to be considered to satisfy (1) include but are not limited to—
(1) The risk of primary building element in a Class 1 or 10 building being damaged by subterranean termites must be adequately minimised by the use of a suitable termite management measure that—
if it serves a non-temporary Class 1 building, has a design life of at least 50 years; or
if it serves a building not specified in (a), has a design life of at least 50 years or the specified design life of the building, whichever is the lesser; or
is easily and readily accessible for replenishment or replacement and is capable of being replenished or replaced.
(2) A termite management measure required by (1), to the degree necessary, must—
be accessible to enable the installation, maintenance and inspection of the termite management measure to be carried out; and
incorporate suitable measures to adequately minimise the risk of the termite management measure inadvertently being damaged, bridged or breached.
Explanatory information
QLD H1P3(1) requires a termite management measure in Queensland to have a design life of at least 50 years unless it is easily and readily accessible for replenishment or replacement and is capable of being replenished or replaced. In recognition that some buildings other than non-temporary Class 1 buildings may be designed to last less than 50 years, the option of the termite management measure having a design life at least equal to that specified for the building is given. If this option is used, the design life of the building should be agreed upon by all relevant stakeholders at the design stage and should form part of the documentation kept by the appropriate authority. It should not be assumed that the design life of 50 years in QLD H1P3(1)(a) and (b) applies to any other provisions of the BCA, unless stated.
An example of a termite management measure that may satisfy QLD H1P3(1)(c) is a chemical reticulation system beneath a concrete floor slab laid directly on the ground, provided that the system is easily and readily accessible for replenishment and is capable of being replenished.
An example of a termite management measure that may not satisfy QLD H1P3(1) for a non-temporary Class 1 building is a hand-sprayed chemical beneath a concrete floor slab laid directly on the ground if the chemical does not have a design life of at least 50 years. The concrete floor slab being laid directly on the ground would prevent the area beneath the slab from being easily and readily accessible for replenishment or replacement of the termite management measure.
An example of a termite management measure being inadvertently bridged or breached is when a person places a garden or mulch over the top of or above the level of a termite management measure enabling termites to bypass the measure.
NCC Title
Termite management measures
NCC State
QLD
NCC Variation Type
Insertion
NCC SPTC Current
Termite management measures
NCC ID
_4057371d-7155-444c-930f-4d858039e78f
Building Classes
2,3,4,5,6,7a,7b,8,9a,9b,9c
Verification Methods
H1V1
Structural reliability
2019: V2.1.1
(1) This Verification Method is only applicable to components with a resistance coefficient of variation of at least 10% and not more than 40%.
(2) For components with a calculated resistance coefficient of variation value less than 10%, then a minimum value of 10% should be used.
(3) Compliance with H1P1(1), (2) and (3) is verified for the design of a structural component for strength when—
the capacity reduction factor satisfies , where are capacity reduction factors for all relevant actions and must contain at least permanent (G), imposed (Q) and wind (W) actions; and
the capacity reduction factors are calculated for target reliability indices for permanent action , for imposed action , for wind action in accordance with the equation: , where—
; and
, where—
= ratio of mean resistance to nominal; and
= ratio of mean action to nominal; and
= correction factor for action; and
= correction factor for resistance; and
= coefficient of variation of the appropriate action as given in Table H1V1a; and
= coefficient of variation of the resistance; and
= appropriate load factor as given in AS/NZS 1170.0; and
= capacity factor for the appropriate action; and
the annual target reliability indices are established as follows:
For situations where it is appropriate to compare with an equivalent Deemed-to-Satisfy product, a resistance model must be established for the equivalent Deemed-to-Satisfy product and must be calculated for the equivalent Deemed-to-Satisfy product in accordance with the equation given at (b).
The target reliability indices thus established, must be not less than those given in Table H1V1b minus 0.5.
For situations where it is not appropriate to compare with an equivalent Deemed-to-Satisfy product, the target reliability index must be as given in Table H1V1b.
(4) The resistance model for the component must be established by taking into account variability due to material properties, fabrication and construction processes and structural modelling.
Table H1V1a Annual action models
Design action
Ratio of mean action to nominal
Coefficient of variation of the action
Permanent action
Imposed action
Wind action (Non-cyclonic)
Wind action (Cyclonic)
Snow action
Earthquake action
Table H1V1b Annual target reliability indices (β)
Type of action
Target reliability index β
Permanent action
4.3
Imposed action
4.0
Wind, snow and earthquake action
3.7
Table Notes
Table H1V1b is applicable for components that exhibit brittle failure similar to concrete as specified in AS 3600.
For components with creep characteristics similar to timber as specified in AS 1720.1, the target reliability index for permanent action shall be increased to 5.0.
The above target reliability indices are based on materials or systems that exhibit creep or brittle failure characteristics similar to timber and concrete.
Table H1V1b may also be applicable to materials or systems that exhibit creep or brittle failure differently to steel, timber or concrete provided that the creep and/or brittle nature of the material or system are properly accounted for in the design model.
The above target reliability indices are also applicable for materials or systems that exhibit ductile failure characteristics.
(1) Compliance with H1P1(1)(c) is verified for structural robustness if (2) and (3) are complied with.
(2) The structure is assessed such that the building remains stable and the resulting collapse does not extend further than the immediately adjacent storeys upon the notional removal in isolation of—
any supporting column; or
any beam supporting one or more columns; or
any segment of a load bearing wall of length equal to the height of the wall.
(3) It is demonstrated that if a supporting structural component is relied upon to carry more than 25% of the total structure, a systematic risk assessment of the building is undertaken and critical high risk components are identified and designed to cope with the identified hazard or protective measures chosen to minimise the risk.
Explanatory information
H1V2 is a means to verify structural robustness of a building or structure in order to meet the requirements of H1P1(1)(c). For further guidance, refer to the ABCB Handbook for Structural Robustness.
(1) Performance RequirementH1P1 is satisfied for earthworks associated with the construction of a building or structure if they are in accordance with Part 3.2 of the ABCB Housing Provisions, provided that the site is classified as A, S, M, H or E in accordance with 4.2.2 of the ABCB Housing Provisions and the work is undertaken in normal site conditions.
(2) Performance RequirementH1P1 is satisfied for an earth retaining structure associated with the construction of a building or structure if it is designed and constructed in accordance with AS 4678.
QLD H1D3 Site preparation2019: 3.1.1, 3.1.2, 3.1.4
Delete subclause H1D3(3) and insert H1D3(3) as follows:
(3) Compliance with Part 3.4 of the ABCB Housing Provisions satisfies Performance Requirement H1P1 and QLD H1P3.
Explanatory information: “Normal” site conditions
“Normal” site conditions relates to parameters such as—
the site conditions not being significantly modified by the removal of previous buildings or other structures; and
the moisture conditions on site being as a result of seasonal and climatic changes; and
the site conditions not being subject to unusual moisture conditions caused by drains, dams, channels, ponds or tanks which are to be maintained or removed; and
large trees have not been recently removed from the site in the area where the building is to be constructed; and
other similar matters.
Further information regarding normal and abnormal site conditions can be found in AS 2870.
AS 4678 contains requirements for earth retaining structures between 800 mm and 15 m in height, and does not apply to structures which are founded in exceptional site conditions (e.g. landslips), are subjected to sustained cyclic loading or are used for the purposes of water-retaining (e.g. dams and reservoirs).
It should be noted that H1D3(2) is only one way of achieving compliance with H1P1. Other ways of complying include the following:
The relevant structural design provisions referenced in H1D2.
The relevant provisions of other Parts of the ABCB Housing Provisions relating to earth retaining structures.
The intent of these requirements is to provide for a termite management system that deters termites from gaining entry to a building via a concealed route. The installation of a termite management system will not stop termite activity from occurring on the site.
(1) Performance RequirementH1P1 is satisfied for the design and construction of footings and slabs if they comply with either (a) or (b):
One of the following:
AS 2870.
AS 3600.
Subject to (2), Section 4 of the ABCB Housing Provisions.
NSW H1D4 Footings and slabs2019: 3.2.0, 3.2.1
Delete subclause H1D4(1) and insert H1D4(1) as follows:
(1) Performance RequirementH1P1 is satisfied for footings and slabs if they are installed in accordance with either (a) or (b):
One of the following:
AS 2870 except that for the purposes of Clause 5.3.3.1 of AS 2870 a damp-proofing membrane is required to be provided.
AS 3600 except that barriers installed beneath slab on ground construction must have a high resistance to damage during construction.
Subject to (2), Section 4 of the ABCB Housing Provisions.
(2) Section 4 of the ABCB Housing Provisions may only be used where—
the footing is on a Class A, S or M site (classified in accordance with AS 2870) with a uniform bearing capacity; and
any slab—
is not more than 18 m long or wide; and
does not contain permanent joints excluding construction joints; and
is of a geometric shape containing only external right angles, other than a slab in (c); and
any footing and slab in (b) has not more than one re-entrant corner; and
the footing and slab are not constructed on soil classified as an aggressive soil type; and
the structure supported by the footing does not contain—
more than two trafficable floors; or
a wall height exceeding 8 m, excluding any gable; and
the footing does not support more than one concrete slab; and
the building does not include wing walls or masonry arches unless they are detailed for movement in accordance with Cement Concrete and Aggregates Australia TN 61; and
single leaf earth or stone masonry walls do not exceed 3 m in height; and
the site is considered to be normal as defined in Part 3.2 of the ABCB Housing Provisions; and
the building is one for which Appendix A of AS 1170.4 contains no specific earthquake design requirements.
Explanatory information: Composite construction
Design requirements for other materials that may be used in combination with the above footing systems, including the use of heavy steel support beams and piled footings, etc. are described in H1D2 and in Section 2 of the ABCB Housing Provisions.
Explanatory information: Split level slab
For the purposes of H1D4(2)(e), split level slabs are considered as one slab. See Figure H1D4a.
For the purposes of H1D4(2)(b)(iii) and (c), a slab is considered geometric if it is square or rectangular and contains 4 external right angles as described in explanatory Figures H1D4b or H1D4c.
Figure H1D4b (explanatory) Geometric slab without re-entrant corner
Figure H1D4c (explanatory) Geometric slab with re-entrant corner
‘(for piers—isolated or engaged)’ is removed from clause 8.5.1(d); and
where clause 8.5.1 requires design as for unreinforced masonry in accordance with Section 7, the member must also be designed as unreinforced masonry in accordance with Table 10.3 and 4.1(a)(i)(C) of AS 3700; or
AS 4773.1 and AS 4773.2.
(5) Performance RequirementH1P1 is satisfied for an isolated masonry pier system if it is designed and constructed in accordance with one of the following, as appropriate:
AS 3700, except—
‘(for piers—isolated or engaged)’ is removed from clause 8.5.1(d); and
where clause 8.5.1 requires design as for unreinforced masonry in accordance with Section 7, the member must also be designed as unreinforced masonry in accordance with Table 10.3 and 4.1(a)(i)(C) of AS 3700.
the building is located in an area with a wind class of not more than N3; and
isolated piers are constructed on footings and/or slabs that comply with H1D4; and
masonry units comply with 5.6.2(4) of the ABCB Housing Provisions and have a minimum compressive strength of—
6.2 MPa for solid or cored units; or
15 MPa for hollow units; and
the roof structure and any walls provide the required lateral bracing for the top of the isolated pier when determined in accordance with AS 3700, except—
‘(for piers—isolated or engaged)’ is removed from clause 8.5.1(d); and
where clause 8.5.1 requires design as for unreinforced masonry in accordance with Section 7, the member must also be designed as unreinforced masonry in accordance with Table 10.3 and 4.1(a)(i)(C) of AS 3700; and
the building site soil classification is A, S or M in accordance with AS 2870; and
the building is not constructed in an alpine area; and
the building is one for which Appendix A of AS 1170.4 contains no specific earthquake design requirements.
(6) Performance RequirementH1P1 is satisfied for masonry accessories if they are constructed and installed in accordance with:
the building is located in an area with a wind class of not more than N3; and
the building is not constructed in an alpine area; and
the building is one for which Appendix A of AS 1170.4 contains no specific earthquake design requirements.
Explanatory information: Composite construction
Design requirements for other materials that may be used in combination with masonry i.e. heavy steel support beams etc. are described in H1D2 and Section 2 of the ABCB Housing Provisions.
Explanatory information: AS 1170.4
There are certain limitations on the application to domestic building structures such as Class 1a and Class 1b buildings in Appendix A of AS 1170.4. These limitations include height, roof slope, etc. For additional information refer to Appendix A of AS 1170.4.
(1) Diagrams depicting framing members and associated terminology used to describe them are set out in Figures H1D6c, H1D6d and H1D6e, and in most cases are applicable for both steel and timber frame members.
(3) Performance RequirementH1P1 is satisfied for steel framing if it is designed and constructed in accordance with one of the following:
Residential and low-rise steel framing:
Design: NASH Standard ‘Residential and Low-Rise Steel Framing’ Part 1.
Design solutions: NASH Standard ‘Residential and Low-Rise Steel Framing’ Part 2.
Steel structures: AS 4100.
Cold-formed steel structures: AS/NZS 4600.
(4) Performance RequirementH1P1 is satisfied for timber framing if it is designed and constructed in accordance with the following, as appropriate:
Design of timber structures: AS 1720.1.
Design of nailplated timber roof trusses: AS 1720.5.
Residential timber-framed construction – non-cyclonic areas: AS 1684.2 or AS 1684.4.
Residential timber-framed construction – cyclonic areas: AS 1684.3.
Installation of particleboard flooring: AS 1860.2.
QLD H1D6 Framing2019: 3.4.0, 3.4.2-3.4.4
Delete subclause H1D6(4) and insert H1D6(4) as follows:
(4) Performance Requirement H1P1 is satisfied for a timber frame if it is designed and constructed in accordance with the following, as appropriate:
Design of timber structures: AS 1720.1.
Design of nailplated timber roof trusses: AS 1720.5.
Residential timber-framed construction – non-cyclonic areas: AS 1684.2.
Residential timber-framed construction – cyclonic areas: AS 1684.3.
Residential timber-framed construction – non-cyclonic areas (simplified): AS 1684.4.
Installation of particleboard flooring: AS 1860.2.
Timber species: In addition to sub-clauses (a) to (f) above, timber used for structural purposes must be a species scheduled for the appropriate use in Schedules A, B or C of Book 2 of the December 2017 version of the "Queensland Government, Department of Agriculture, Fisheries and Forestry - Construction timbers in Queensland, Book 1 and Book 2: Properties and specifications for satisfactory performance of construction timbers in Queensland - Class 1 and 10 buildings (Houses, carports, garages, greenhouses and sheds)".
(5) Performance RequirementH1P1 is satisfied for structural steel sections if they are designed and constructed in accordance with one of the following:
Steel structures: AS 4100.
Cold-formed steel structures: AS/NZS 4600.
For structural stability, strength and deflection, and subject to (6), Part 6.3 of the ABCB Housing Provisions.
For corrosion protection, clause 6.3.9 of Part 6.3 of the ABCB Housing Provisions.
(6) For the purposes of (5)(c), Part 6.3 of the ABCB Housing Provisions may only be used where—
the building is located in an area with a wind class of not more than N3; and
the first dimension of steel sections is installed vertically; and
all loads are evenly distributed (unless otherwise noted or allowed for); and
the building is one for which Appendix A of AS 1170.4 contains no specific earthquake design requirements; and
the structural steel members are not subject to snow loads; and
the structural steel members are in buildings within geometric limits set out in clause 1.2 of AS 4055.
(7) The use of structural software is subject to the following:
Structural software used in computer aided design of a building or structure, that uses design criteria based on the Deemed-to-Satisfy Provisions of Section H, including its referenced documents, for the design of steel or timber trussed roof and floor systems and framed building systems, must comply with the ABCB Protocol for Structural Software.
Structural software referred to in (a) can only be used for buildings within the following geometric limits:
The distance from ground level to the underside of eaves must not exceed 6 m.
The distance from ground level to the highest point of the roof, neglecting chimneys, must not exceed 8.5 m.
The building width including roofed verandahs, excluding eaves, must not exceed 16 m.
The building length must not exceed five times the building width.
The roof pitch must not exceed 35 degrees.
The requirements of (a) do not apply to design software for individual frame members such as electronic tables similar to those provided in—
AS 1684; or
NASH Standard – Residential and Low-Rise Steel Framing, Part 2.
Table H1D6a Effective load width for structural steel bearers and strutting beams—Single spanning rafter or joist
Design member
Member 1
Member 2
Effective load width
0.5 x Span 1
0.5 x (Span 1 + Span 2)
Table H1D6b Effective load width for structural steel bearers and strutting beams—Continuous spanning rafter or joist
Design Member
Member 1
Member 2
Member 3
Effective load width
0.4 x Span 1
0.6 x (Span 1 + Span 2)
0.5 x (Span 2) + Span 3
Table Notes
The length of Span 3 must not be more than 0.5 x Span 2.
Figure H1D6a Effective load width for structural steel bearers and strutting beams—Single spanning rafter or joist
Figure H1D6b Effective load width for structural steel bearers and strutting beams—Continuous spanning rafter or joist
Figure H1D6c Span and spacing terms
Figure H1D6d Typical roof framing members
Figure H1D6e Floor, wall, ceiling and other framing members
Figure H1D6f Steel member descriptions—abbreviations and profiles
Explanatory information
For the purposes of H1D6(2), design requirements for other materials used in combination with steel or timber framing, including the use of concrete floors, structural steel support beams, etc. are described in the following locations within the ABCB Housing Provisions:
The weight of roof or ceiling insulation, particularly if additional ceiling insulation is used for compliance with the energy efficiency provisions, needs to be considered in the selection of plasterboard, plasterboard fixings and building framing.
A map indicating cyclonic regions of Australia is contained in Part 2.2.
There are certain limitations on the application to domestic structures such as Class 1a and 1b buildings in Appendix A of AS 1170.4. These limitations include building height, roof slope, etc. For additional information refer to Appendix A of AS 1170.4.
H1D6(7) does not apply where a software package simply eliminates manual calculations and the process of the package requires identical methodology as that undertaken manually, e.g. AS 1684 span tables and bracing calculations.
The application of Part 6.3 of the ABCB Housing Provisions requires all loads to be distributed evenly unless they are noted otherwise or allowed for within the construction and placement of relevant building elements. Part 6.3 of the ABCB Housing Provisions allows for point loads to be applied to strutting beams only if the loads are located within the middle third of the beam’s span. In any other case, designs should be carried out in accordance with either H1D6(5)(a) or (b), or by a suitably qualified practitioner.
Explanatory information: Explanation of first dimension of steel section installed vertically
H1D6(6) provides that Part 6.3 of the ABCB Housing Provisions satisfies Performance RequirementH1P1 with respect to structural stability, strength and deflection if the ‘first dimension’ of a steel section is installed vertically.
For example, a 150 x 90 x 8 UA is used as a structural steel member (lintel) to support masonry over an opening.
The “first dimension” designated is 150 mm (b1) and is the vertical leg that resists bending loads over the width of the opening. This leg must be installed in the vertical plane.
The 90 mm (b2) designation refers to the horizontal leg that rests under the masonry elements and transfers direct loads to the extremities of the opening while the 8 mm (t) designation refers to the thickness of the steel section.
(1) Diagrams depicting relevant roofing and supporting members and associated terminology used to describe them are set out in Figure H1D7a and Figure H1D7b.
(2) Performance RequirementH1P1 is satisfied for sheet roofing if it complies with one or a combination of the following:
Metal roofing:
AS 1562.1; and
in wind regions B, C and D in accordance with Figure 2.2.3 in Section 2 of the ABCB Housing Provisions (cyclonic areas), metal roof assemblies, their connections and immediate supporting members must be capable of remaining in position notwithstanding any permanent distortion, fracture or damage that might occur in the sheet or fastenings under the pressure sequences A to G defined in Table H1D7.
Plastic sheet roofing: AS 1562.3.
Metal sheet roofing: Part 7.2 of the ABCB Housing Provisions, provided the building is located in an area with a wind class of not more than N3.
(3) Performance RequirementH1P1 is satisfied for roof cladding if it complies with one or a combination of the following:
Terracotta, fibre-cement and timber slates and shingles: AS 4597.
For roof tiles—
AS 2050; or
Part 7.3 of the ABCB Housing Provisions, provided—
the building is located in an area with a wind class of not more than N3; and
the roof tiles comply with AS 2049; and
the roof has a pitch of not less than 15 degrees and not more than 35 degrees.
(4) Performance RequirementH1P1 is satisfied for timber and composite wall cladding if it is designed and constructed in accordance with—
for autoclaved aerated concrete wall cladding, AS 5146.1; or
for wall cladding, Part 7.5 of the ABCB Housing Provisions.
(5) Performance RequirementH1P1 is satisfied for a metal wall cladding if it is designed and constructed in accordance with AS 1562.1.
Table H1D7 Low-High-Low pressure sequence
Sequence
Number of cycles
Load
A
4500
0 to 0.45 Pt
B
600
0 to 0.6 Pt
C
80
0 to 0.8 Pt
D
1
0 to 1.0 Pt
E
80
0 to 0.8 Pt
F
600
0 to 0.6 Pt
G
4500
0 to 0.45 Pt
Table Notes
Pt is the ultimate limit state wind pressure on internal and external surfaces as determined in accordance with AS/NZS 1170.2, modified by an appropriate factor for variability, as determined in accordance with Table B1 of AS/NZS 1170.0.
The rate of load cycling must be less than 3 Hz.
The single load cycle (sequence D) must be held for a maximum of 10 seconds.
Figure H1D7a Section of a typical sheet roof
Figure H1D7b Section of a typical tile roof
Explanatory information
The requirements of H1D7(2)(a)(ii) must be read in conjunction with the provisions of AS/NZS 1170.2. The ABCB commissioned research to establish a nationally consistent testing regime for metal roof cladding assemblies in cyclonic areas. The results of this research are contained in H1D7(2)(a)(ii).
Low cycle fatigue cracking of metal roof cladding elements during tropical cyclones is a complex process where small changes in load, geometry or material properties can significantly affect the fatigue performance of the cladding system (includes immediate supports, fixings and cladding). The consequences of failure of an element can quickly lead to more elements progressively failing. These failed elements become wind driven debris and so pose a threat to people and other structures as potential missiles.
If a system does not successfully resist the fatigue loading sequence in Table H1D7, it does not comply. The test section consists of cladding elements, fastenings and immediate supporting members assembled together in a manner identical to those parts of the particular roof which the test section is intended to replicate.
Explanatory information
In Western Australia state variations apply to wind Regions B and D, this includes wind region B2 as referenced in AS/NZS 1170.2.
The state variation for wind region B or B2 will ensure that designers consider the combination of peak external pressures and increased internal pressures in design of buildings and use a cyclonic (C) classification instead of non-cyclonic (N) classification. The definition of design wind speed is varied in WA Schedule 1 to identify that wind Region B is a C classification in Western Australia. Other changes have also been made to reflect this.
In addition to a variation to clause H1D7 of NCC Volume Two, and clauses 2.2.3 and 2.2.4 of the ABCB Housing Provisions Standard - a variation is made to the application of AS/NZS 1170.2 and AS 4055 (when used as a primary referenced document, secondary or subsequent referenced document). Refer to the WA Schedule 2 and WA Part 2.3.
The state variation for wind region D applies only to those parts of region D located north of the Tropic of Capricorn. The 2021 edition of AS/NZS 1170.2 includes a reduction in design wind speeds for wind region D. The variation will retain similar design wind speeds for wind region D as the 2011 edition of AS/NZS 1170.2 previously referenced in the National Construction Code.
NCC Title
Roof and wall cladding
NCC State
WA
NCC Variation Type
Replacement
NCC SPTC Current
Roof and wall cladding
NCC ID
_1c2b8429-03ca-4b0c-b998-5f197b888a18
(1) Diagrams depicting relevant roofing and supporting members and associated terminology used to describe them are set out in Figure H1D7a and Figure H1D7b.
(2) Performance RequirementH1P1 is satisfied for sheet roofing if it complies with one or a combination of the following:
Metal roofing:
AS 1562.1; and
in wind regions C and D in accordance with Figure 2.2.3 in Section 2 of the ABCB Housing Provisions (cyclonic areas), metal roof assemblies, their connections and immediate supporting members must be capable of remaining in position notwithstanding any permanent distortion, fracture or damage that might occur in the sheet or fastenings under the pressure sequences A to G defined in Table H1D7.
Plastic sheet roofing: AS 1562.3.
Metal sheet roofing: Part 7.2 of the ABCB Housing Provisions, provided the building is located in an area with a wind class of not more than N3.
(3) Performance RequirementH1P1 is satisfied for roof cladding if it complies with one or a combination of the following:
Terracotta, fibre-cement and timber slates and shingles: AS 4597.
For roof tiles—
AS 2050; or
Part 7.3 of the ABCB Housing Provisions, provided—
the building is located in an area with a wind class of not more than N3; and
the roof tiles comply with AS 2049; and
the roof has a pitch of not less than 15 degrees and not more than 35 degrees.
(4) Performance RequirementH1P1 is satisfied for timber and composite wall cladding if it is designed and constructed in accordance with—
for autoclaved aerated concrete wall cladding, AS 5146.1; or
for wall cladding, Part 7.5 of the ABCB Housing Provisions.
(5) Performance RequirementH1P1 is satisfied for a metal wall cladding if it is designed and constructed in accordance with AS 1562.1.
Table H1D7 Low-High-Low pressure sequence
Sequence
Number of cycles
Load
A
4500
0 to 0.45 Pt
B
600
0 to 0.6 Pt
C
80
0 to 0.8 Pt
D
1
0 to 1.0 Pt
E
80
0 to 0.8 Pt
F
600
0 to 0.6 Pt
G
4500
0 to 0.45 Pt
Table Notes
Pt is the ultimate limit state wind pressure on internal and external surfaces as determined in accordance with AS/NZS 1170.2, modified by an appropriate factor for variability, as determined in accordance with Table B1 of AS/NZS 1170.0.
The rate of load cycling must be less than 3 Hz.
The single load cycle (sequence D) must be held for a maximum of 10 seconds.
Figure H1D7a Section of a typical sheet roof
Figure H1D7b Section of a typical tile roof
Explanatory information
The requirements of H1D7(2)(a)(ii) must be read in conjunction with the provisions of AS/NZS 1170.2. The ABCB commissioned research to establish a nationally consistent testing regime for metal roof cladding assemblies in cyclonic areas. The results of this research are contained in H1D7(2)(a)(ii).
Low cycle fatigue cracking of metal roof cladding elements during tropical cyclones is a complex process where small changes in load, geometry or material properties can significantly affect the fatigue performance of the cladding system (includes immediate supports, fixings and cladding). The consequences of failure of an element can quickly lead to more elements progressively failing. These failed elements become wind driven debris and so pose a threat to people and other structures as potential missiles.
If a system does not successfully resist the fatigue loading sequence in Table H1D7, it does not comply. The test section consists of cladding elements, fastenings and immediate supporting members assembled together in a manner identical to those parts of the particular roof which the test section is intended to replicate.
comply with Part 8.4 of the ABCB Housing Provisions.
Explanatory information: AS 2047
AS 2047 specifies requirements for the design, testing and manufacture of windows. The reference to windows in AS 2047 includes certain types of louvres and glazed doors that may be sliding, swinging, French or bi-fold doors.
AS 2047 does not cover assemblies that are internal or revolving doors, fixed louvres, skylights, rooflights and windows not installed in the vertical plane, windows in greenhouses or horticultural buildings, frameless sliding or swinging doors, windows constructed on site, one-off untested architectural designed windows, second-hand, recycled or reused windows and heritage windows defined by relevant State and Territory authorities.
Explanatory information: AS 1288
In relation to building work covered by NCC Volume Two and the ABCB Housing Provisions, AS 1288 does not cover the selection and installation of glass for windows and doors in heritage buildings, restoration or repairs to leadlights, glass blocks, bricks or pavers.
Explanatory information: AS 4055
Clause 1.2 of AS 4055 sets out geometric limitations that include the following:
The distance from the ground level adjacent to the building to the underside of eaves is not to exceed 6.0 m.
The distance from the ground level of the building to the highest point of the roof, excluding chimneys is not to exceed 8.5 m.
The width of the building, including verandas, but excluding eaves, is not to exceed 16.0 m.
The length of the building is not to exceed five times its width.
Performance RequirementH1P1 for Class 1 and 10 buildings constructed in areas subject to seismic activity is satisfied if the building is constructed in accordance with Section 2 of the ABCB Housing Provisions.
Explanatory information
Most domestic structures are not required to be specifically designed for earthquakes.
There are certain limitations on the application to domestic structures such as Class 1a and 1b buildings in Appendix A of AS 1170.4. These limitations include building height, roof slope, etc. For additional information refer to Appendix A of AS 1170.4.
Building work in designated flood hazard areas is regulated by the Building Act 1975 and the Queensland Development Code 3.5 - Construction of buildings in flood hazard areas.
NCC ID
idm7278
NCC Blurbs
(1) Performance Requirement H1P2 for Class 1 buildings constructed in a flood hazard area is satisfied if the building is constructed in accordance with the ABCB Standard for Construction of Buildings in Flood Hazard Areas.
(2) The definitions of flood hazard area and freeboard in the ABCB Standard for Construction of Buildings in Flood Hazard Areas are replaced with those in Vic Schedule 1.
(3) The definition of defined flood level in the ABCB Standard for Construction of Buildings in Flood Hazard Areas is replaced with that in Schedule 1.
NCC Title
Flood hazard areas
NCC State
VIC
NCC Variation Type
Replacement
NCC SPTC Current
Flood hazard areas
NCC ID
_d07af715-6454-4309-bc3a-8d1aab1972db
Building Classes
2,3,4,5,6,7a,7b,8,9a,9b,9c,10a,10b,10c
Performance RequirementH1P2 for a Class 1 building constructed in a flood hazard area is satisfied if the building is constructed in accordance with the ABCB Standard for Construction of Buildings in Flood Hazard Areas.
the deck or balcony is not located in an alpine area; and
the height of the deck or balcony is not more than 3 m measured from the uppermost finished floor surface of the deck or balcony at any point to the top of any supporting footing; and
the deck or balcony does not cantilever off the external wall; and
the total imposed load on the deck or balcony does not exceed 2 kPa; and
the deck or balcony framing including member sizes, spans and spacing, bracing for racking and shear forces, fixings and structural supports complies with H1D2; and
steel framing constructed in accordance with H1D6(3); and
timber framing is constructed in accordance with H1D6(4); and
the external wall supporting the deck or balcony is constructed of—
190 mm thick fully core-filled concrete masonry, reinforced with vertical N12 bars at not more than 600 mm centres; or
the external wall referred to in (i) must be continuous from the upper most surface of the deck or balcony to the supporting footing and contain no openings or lintels below the deck or balcony; and
the waling plate is fixed to the external wall in accordance with clause 12.3.2 of the ABCB Housing Provisions and attached by—
fixing the waling plate through wall cladding complying with H1D7(4) or H1D7(5), provided the cladding is directly fixed to the external wall; or
removing parts of the wall cladding so that the waling plate is directly fixed to the external wall, with—
the junction of the waling plate and the external wall flashed in accordance with clause 12.3.3 of the ABCB Housing Provisions; and
the cladding restored to its original strength by installing blocking supports as necessary on completion of installation; and
the deck or balcony is braced to prevent lateral movement in accordance with clause 12.3.4 of the ABCB Housing Provisions.
Explanatory information
A 2 kPa imposed load is commensurate with domestic and residential activities associated with Class 1 buildings (e.g. dwellings with limited occupancy and restricted public access) and is not appropriate for applications where the deck or balcony supports heavy equipment, spa/bathing pools or circumstances where the deck or balcony is intended for community access (e.g. applications with a mid-high occupancy and possibility of public access).
If the design live load of the deck or balcony is more than 2 kPa, the framing members of the deck or balcony must be designed by a professional engineer or other appropriately qualified person in accordance with the relevant structural design manuals in Part 2.2 of the ABCB Housing Provisions.
H1D11(k)(ii) requires consideration to be given to restoring cladding, weatherproofing and structural properties. Other considerations include restoring the appropriate sound and thermal insulation, and the capacity to maintain an FRL where required.
H1D11 describes the circumstances under which the methods of attachment described in this Part are deemed appropriate.
Where a deck or balcony is constructed outside the conditions listed in H1D11, e.g. attachment to a masonry veneer wall, the method of attachment to the building or structure must be designed by a professional engineer or other appropriately qualified person in accordance with the relevant structural design manuals in Part 2.2 of the ABCB Housing Provisions. Such a design will need to consider the suitability of the wall to withstand the loads imposed by the deck or balcony, and the capacity of the connections.
Examples of external wall construction that are outside the application of H1D11 include a masonry external wall that is not fully core-filled, cavity masonry and masonry veneer construction where fasteners may be subject to withdrawal.
An alternative to attaching a deck or balcony directly to an external wall includes providing supporting piers, posts or columns or the like parallel to the wall line or at right angles to the wall.
Performance RequirementH1P1 is satisfied for piled footings if they are designed and installed in accordance with AS 2159.
Explanatory information
Slab construction—design requirements for other elements of construction that may be used in combination with the above piled footing systems, including concrete slabs, etc. are described in H1D2 for Structural provisions and H1D4 for Footings and slabs.