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Part 3.12.1 Building Fabric

3.12.1 Application

(a)

The provisions of 3.12.1.1 to Open link in same page3.12.1.5 apply to—

(i)

a Class 1 building; and

(ii)

a Class 10a building with a Open link in same pageconditioned space.

(b)

The provisions of Open link in same page3.12.1.6 apply to a Class 1 building with an attached Class 10a building.

Acceptable construction practice

3.12.1.1 Building fabric thermal insulation

(a)

Where Open link in same pagerequired, insulation must comply with AS/NZS 4859.1 and be installed so that it—

(i)

abuts or overlaps adjoining insulation other than at supporting members such as columns, studs, noggings, joists, furring channels and the like where the insulation must butt against the member; and

(ii)

forms a continuous barrier with ceilings, walls, bulkheads, floors or the like that inherently contribute to the thermal barrier; and

Explanatory information:

For example, in a two storey house with the second storey set back, the insulation in the first storey wall, the second storey wall and the roof over the set-back must be continuous. Therefore if the roof over the set-back has insulation on a horizontal ceiling, then insulation is also needed on the vertical in any ceiling space in order to connect the ceiling insulation to the second storey wall.

(iii)

does not affect the safe or effective operation of a Open link in same pagedomestic service or fitting.

Explanatory information:

Care should be taken when installing insulation to ensure that it does not interfere with the safety or performance of Open link in same pagedomestic services and fittings such as heating flues, recessed light fittings, light transformers, gas appliances and general plumbing and electrical components. This includes providing appropriate clearance as detailed in relevant legislation and referenced standards such as for electrical, gas and fuel oil installations.

(b)

Where Open link in same pagerequired, Open link in same page reflective insulation must be installed with—

(i)

the necessary airspace, to achieve the required Open link in same pageR-Value between a reflective side of the Open link in same pagereflective insulation and a building lining or cladding; and

Explanatory information: Airspace adjoining reflective insulation

For Open link in same pagereflective insulation and the adjoining airspace to achieve its tested Open link in same pageR-Value, the airspace needs to be a certain width. This width varies depending on the particular type of Open link in same pagereflective insulation and the Open link in same pageR-Value to be achieved.

(ii)

the Open link in same pagereflective insulation closely fitted against any penetration, door or Open link in same pagewindow opening; and

(iii)

the Open link in same pagereflective insulation adequately supported by framing members; and

(iv)

each adjoining sheet of roll membrane being—

(A)

overlapped not less than 150 mm; or

(B)

taped together.

Explanatory information: Adjoining sheets of roll membrane

Where Open link in same pagereflective insulation also acts as a vapour barrier or sarking, both the minimum overlap and taping may be necessary.

(c)

Where Open link in same pagerequired, bulk insulation must be installed so that—

(i)

it maintains its position and thickness, other than where it crosses roof battens, water pipes, electrical cabling or the like; and

Explanatory information: Compression of bulk insulation

The Open link in same pageR-Value of bulk insulation is reduced if it is compressed. The allocated space for bulk insulation must therefore allow the insulation to be installed so that it maintains its correct thickness when using the product’s stated Open link in same pageR-Value, otherwise the Open link in same pageR-Value needs to be reduced to account for any compression. This is particularly relevant to wall and cathedral ceiling framing whose members can only accommodate a limited thickness of insulation. In some instances, larger framing members or thinner insulation material, such as polystyrene boards, may be necessary to ensure that the insulation achieves its Open link in same pagerequired  Open link in same pageR-Value.

(ii)

in a ceiling, where there is no bulk insulation or Open link in same pagereflective insulation in the Open link in same pageexternal wall beneath, it overlaps the Open link in same pageexternal wall by not less than 50 mm.

Explanatory information:
  1. The Open link in same pageR-Value of Open link in same pagereflective insulation and its adjoining airspace is affected by the width of the airspace between a reflective side of the Open link in same pagereflective insulation and the building lining or cladding. For further information on Open link in same pagereflective insulation, refer to the explanatory information accompanying Open link in same pageFigure 3.12.1.1.
  2. Artificial cooling of buildings in some climates can cause condensation to form inside the layers of the building Open link in same pageenvelope. Such condensation can cause significant structural or cosmetic damage to the Open link in same pageenvelope before it is detected. Associated mould growth may also create health risks to the occupants. Effective control of condensation is a complex issue. In some locations a fully sealed vapour barrier may need to be installed on the more humid, or generally warmer, side of the insulation.

3.12.1.2 Roofs

(a)

Subject to Open link in same page(b) and Open link in same page3.12.1.2(e), a roof must—

(i)

achieve the Open link in same pageTotal R-Value specified in Open link in same pageTable 3.12.1.1a for the direction of heat flow; and

(ii)

where a pitched roof has a flat ceiling, have not less than 50% of the added insulation laid on the ceiling.

(b)

In Open link in same pageclimate zones 1, 2, 3, 4 and 5 the Open link in same pageTotal R-Value specified in Open link in same pageTable 3.12.1.1a is reduced by 0.5 where the Open link in same pagerequired insulation is laid on the ceiling and the roof space is ventilated by—

(i)

gable vents, ridge vents, eave vents, roof vents or the like that—

(A)

are evenly distributed to allow an unobstructed flow of air; and

(B)

are located to ensure, where practicable, there are no dead airspaces; and

(C)

have an aggregate fixed open area of not less than 1.0% of the ceiling area; or

(ii)

not less than 2 wind-driven roof ventilators having an aggregate opening area of not less than 0.14 m2 in conjunction with gable vents, ridge vents, eave vents, roof vents or the like having an aggregate fixed open area of not less than 0.2% of the ceiling area.

Table 3.12.1.1a ROOF AND CEILING—MINIMUM TOTAL R-VALUE

Climate zone 1 2 3 4 and 5 6 and 7 8
Altitude less than 300 m Altitude 300 m or more
Direction of heat flow Downwards Downwards and upwards Upwards
Minimum Total R-Value for a roof with an upper surface solar absorptance value of not more than 0.4 3.1 4.1 4.1 4.1 4.6 6.3
Minimum Total R-Value for a roof with an upper surface solar absorptance value of more than 0.4 but not more than 0.6 4.1 4.6 4.6 4.6 5.1 6.3
Minimum Total R-Value for a roof or ceiling with a roof upper surface solar absorptance value of more than 0.6 5.1 5.1 5.1 5.1 5.1 6.3
Note: Altitude means the height above the Australian Height Datum at the location where the building is to be constructed.
Explanatory information:
  1. The roof space ventilation option, in climate zones 1, 2, 3, 4 and 5, applies to a pitched roof with a flat ceiling to ensure that efficient cross ventilation is achieved in the roof space to remove hot air. Roof space ventilation is generally not suitable for most flat, skillion, cathedral ceiling and similar roof types because of the lack of space between the ceiling and roof.
  2. Care should be taken to ensure that the roof ventilation openings do not allow rain penetration and that they comply with appropriate bushfire provisions.
  3. Gaps between roof tiles with sarking (or reflective insulation at rafter level) and metal sheet roofing are not acceptable methods of providing roof space ventilation.
  4. Compliance with the ventilation provisions in 3.12.1.2(b)(ii) may result in the ingress of wind driven rain, fine dust, corrosive aerosols, or stimulate the growth of mould or fungus in the roof enclosure. Consideration should therefore be given to the surrounding environmental features, including exposure to marine or industrial environments, prior to adopting this as an alternative to the roof insulation provisions in 3.12.1.2(b)(i).
  5. A low solar absorptance roof reduces the flow of heat from solar radiation better than a high solar absorptance roof. A roof with a solar absorptance value of less than 0.4 typically corresponds to a roof of light colour such as white, off-white or cream. Typical absorptance values based on ASTM E903 are as follows.

Typical Absorptance Values

Colour Value
Slate (dark grey) 0.90
Red, green 0.75
Yellow, buff 0.60
Zinc aluminium — dull 0.55
Galvanised steel — dull 0.55
Light grey 0.45
Off white 0.35
Light cream 0.30
  1. The direction of heat flow in Open link in same pageTable 3.12.1.1a is considered to be the predominant direction of heat flow for the hours of occupation of the building. It takes into account the higher rate of occupancy of houses at night time rather than day time.
  2. 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.
(c)

A roof that—

(ii)

has metal sheet roofing directly fixed to metal purlins, metal rafters or metal battens; and

(iii)

does not have a ceiling lining or has a ceiling lining fixed directly to those metal purlins, metal rafters or metal battens (see Open link in same pageFigure 3.12.1.1(b)),

must have a thermal break, consisting of a material with an Open link in same pageR-Value of not less than 0.2, installed between the metal sheet roofing and its supporting metal purlins, metal rafters, or metal battens.

(d)

A roof, or roof and associated ceiling, is deemed to have the Open link in same pageTotal R-Value in Open link in same pageFigure 3.12.1.1.

Figure 3.12.1.1 TOTAL R-VALUE FOR TYPICAL ROOF AND CEILING CONSTRUCTION

Roof construction description Total R-Value

(a) Flat roof, skillion roof and cathedral ceiling — Ceiling lining under rafter

Show Full Sized ImageFigure 3.12.1.1a Flat roof, skillion roof and cathedral ceiling — Ceiling lining under rafter

Unventilated Down 0.48
Up 0.36

(b) Flat roof, skillion roof and cathedral ceiling — Exposed rafters

Show Full Sized ImageFigure 3.12.1.1b Flat roof, skillion roof and cathedral ceiling — Exposed rafters

Unventilated Down 0.44
Up 0.38

(c) Pitched roof with flat ceiling — Tiled roof

Show Full Sized ImageFigure 3.12.1.1c Pitched roof with flat ceiling — Tiled roof

Ventilated Down 0.74
Up 0.23
Unventilated Down 0.56
Up 0.41

(d) Pitched roof with flat ceiling — Metal roof

Show Full Sized ImageFigure 3.12.1.1d Pitched roof with flat ceiling — Metal roof

Ventilated Down 0.72
Up 0.21
Unventilated Down 0.54
Up 0.39

Notes:

  1. The Open link in same pageTotal R-Value of the roof and ceiling construction in Open link in same pageFigure 3.12.1.1 is based on there being a roof space. If the roof space is filled, the roof space Open link in same pageR-Value needs to be subtracted from the Open link in same pageTotal R-Value of the roof and ceiling materials.
  2. The Open link in same pageTotal R-Value of the unventilated roof and ceiling construction in Open link in same pageFigure 3.12.1.1(c) for tiled roofs are based on there being Open link in same pagesarking-type material which would prevent ventilation of the roof space through the gaps in the roof tiles.
Explanatory information:
  1. Typical construction:

    Open link in same pageFigure 3.12.1.1 provides examples of various roof and ceiling construction. The Open link in same pageR-Value of the Open link in same pagerequired insulation is calculated by subtracting the inherent Open link in same pageTotal R-Value of the roof and ceiling construction from the Open link in same pageTotal R-Value in Open link in same pageTable 3.12.1.1. The inherent Open link in same pageTotal R-Value of the typical roof and ceiling has been determined by adding together the Open link in same pageR-Values of the outdoor air film, roof cladding, roof airspace, ceiling sheet lining and internal film.

  2. The Open link in same pageTotal R-Value of the roof and ceiling materials may need to be adjusted if other building elements such as sarking are also installed. For example, sarking or sheet insulation under tiles may change a roof space from “ventilated” to “unventilated”.
  3. Thermal bridging:

    Irrespective of the framing material used, the minimum added Open link in same pageR-Value specified in Open link in same pageFigures 3.12.1.1 and Open link in same page3.12.1.3 and Open link in same pageTable 3.12.1.4 is deemed to include the effect of thermal bridging created by framing members in situations other than described in explanatory note 4.

  4. Thermal break:

    Because of the high thermal conductance of metal, a thermal break is to be provided where the ceiling lining of a house is fixed directly to the underside of the metal purlins or metal battens of a metal deck roof or where there is no ceiling lining. The purpose of the thermal break is to ensure that the thermal performance of this form of roof construction is comparable to that of a similar roof with timber purlins or timber battens.

    A thermal break may be provided by materials such as timber, expanded polystyrene strips, plywood or compressed bulk insulation. The material used as a thermal break must separate the metal purlins or metal battens from the metal deck roofing and achieve the specified Open link in same pageR-Value. Open link in same pageReflective insulation alone is not suitable for use as a thermal break because it requires an adjoining airspace to achieve the specified Open link in same pageR-Value (see explanatory note 6).

    For the purposes of Open link in same page3.12.1.2(c), expanded polystyrene strips of not less than 12 mm thickness, compressed bulk insulation, and timber of not less than 20 mm thickness are considered to achieve an Open link in same pageR-Value of not less than 0.2.

  5. Location of insulation:

    The thermal performance of the roof may vary depending on the position of the insulation, the climatic conditions, the design of the house and the way in which it is operated. For example, insulation installed under the roof, rather than on the ceiling, of a conditioned house with a large roof space is less effective because of the additional volume of roof airspace that would need to be heated or cooled. Conversely, for an unconditioned house, the use of Open link in same pagereflective insulation is more effective when placed directly under the roof.

  6. Choice of insulation:

    There are a number of different insulation products that may be used to achieve the minimum added Open link in same pageR-Value. However, care should be taken to ensure that the choice made is appropriate for the construction and climatic conditions as the location and relationship between options in Open link in same pageFigures 3.12.1.1 and Open link in same page3.12.1.3 and Open link in same pageTable 3.12.1.4 may not be suitable in all circumstances for both practical and technical reasons. For instance, in some Open link in same pageclimate zones, insulation should be installed with due consideration of condensation and associated interaction with adjoining building materials. As an example, Open link in same pagereflective insulation or sarking installed on the cold side of the building Open link in same pageenvelope should be vapour permeable.

    Open link in same pageReflective insulation is considered to provide the following additional Open link in same pageR-Values when used in conjunction with the Open link in same pageTotal R-Value of a pitched roof and flat ceiling construction described in Open link in same pageFigure 3.12.1.1. To achieve these values, the Open link in same pagereflective insulation must be laid directly under the roof cladding and have a minimum airspace of 15 mm between a reflective side of the Open link in same pagereflective insulation and the adjoining lining or roof cladding (see Open link in same page3.12.1.1(b)).

    The actual Open link in same pageR-Value added by Open link in same pagereflective insulation and its adjoining airspace should be determined for each product in accordance with the standard prescribed in Open link in same page3.12.1.1(a), which takes into consideration factors such as the number of adjacent airspaces, dimensions of the adjacent airspace, whether the space is ventilated and the presence of an anti-glare coating. When Open link in same pagereflective insulation has an anti-glare coating on one side, the emittance value of that side will be greater than the value of the uncoated side.

    Also, where another emittance value for Open link in same pagereflective insulation is used (other than the value used in the table below), care should be taken to ensure that the number of airspaces allowed for is consistent with the form of construction and whether the airspace is reflective, partially reflective or non-reflective. Where bulk insulation fills the airspace, the Open link in same pageTotal R-Value should be reduced to take account of the loss of airspace.

Emittance of added reflective insulation Direction of heat flow R-Value added by reflective insulation
Pitched roof (>10 o ) with horizontal ceiling Flat skillion or pitched roof (≤10 o ) with horizontal ceiling Pitched roof with cathedral ceilings
Unventilated roof space Ventilated roof space 15° to not more than 25° pitch more than 25° to not more than 35° pitch more than 35° to 45° pitch

0.2 outer

0.05 inner

Downwards 1.12 1.21 1.28 0.96 0.86 0.66

0.2 outer

0.05 inner

Upwards 0.75 0.59 0.68 0.72 0.74 0.77

0.9 outer

0.05 inner

Downwards 0.92 1.01 1.06 0.74 0.64 0.44

0.9 outer

0.05 inner

Upwards 0.55 0.40 0.49 0.51 0.52 0.53

Notes:

  1. The direction of heat flow applicable in each Open link in same pageclimate zones specified in Open link in same pageTable 3.12.1.1a.
  2. Ventilated roof space means ventilated in accordance with Open link in same page3.12.1.2(b).
(e)

Where, for operational or safety reasons associated with exhaust fans, flues or recessed downlights, the area of Open link in same pagerequired ceiling insulation is reduced, the loss of insulation must be compensated for by increasing the Open link in same pageR-Value of insulation in the remainder of the ceiling in accordance with Open link in same pageTable 3.12.1.1b.

Table 3.12.1.1b ADJUSTMENT OF MINIMUM R-VALUE FOR LOSS OF CEILING INSULATION

Percentage of ceiling area uninsulated Minimum Open link in same pageR-Value of ceiling insulation Open link in same pagerequired to satisfy 3.12.1.2(a)
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Adjusted minimum Open link in same pageR-Value of ceiling insulation Open link in same pagerequired to compensate for loss of ceiling insulation area
0.5% to less than 1.0% 1.0
1.6
2.2
2.8
3.4
4.0
4.7
5.4
6.2
6.9  
1.0% to less than 1.5% 1.1
1.7
2.3
2.9
3.6
4.4
5.2
6.1
7.0  
1.5% to less than 2.0% 1.1
1.7
2.4
3.1
3.9
4.8
5.8
6.8  
2.0% to less than 2.5% 1.1
1.8
2.5
3.3
4.2
5.3
6.5  
2.5% to less than 3.0% 1.2
1.9
2.6
3.6
4.6
5.9  
3.0% to less than 4.0% 1.2
2.0
3.0
4.2
5.7 Not permitted
4.0% to less than 5.0% 1.3
2.2
3.4
5.0  
5.0% or more  
Note: Where the minimum Open link in same pageR-Value of ceiling insulation Open link in same pagerequired to satisfy Open link in same page3.12.1.2(a) is between the values stated, interpolation may be used to determine the adjusted minimum Open link in same pageR-Value.

 

Explanatory information:
  1. When considering the reduction of insulation because of exhaust fans, flues or recessed downlights, 0.5% of the ceiling area for a 200 m2 house would permit 2 bathroom heater-light assemblies, a laundry exhaust fan, a kitchen exhaust fan and either approximately 20 recessed down-lights with 50 mm clearance to insulation, 10 recessed downlights with 100 mm clearance to insulation or only 3 recessed downlights with 200 mm clearance to insulation.
  2. Note that Table 3.12.1.1b refers to the R-Value of the insulation located on the ceiling and is not the Total R-Value Open link in same pagerequired of the roof. The roof has an inherent R-Value and there may also be insulation at the roof line.
  3. Note that 3.12.1.2(e) does not require an increase in ceiling insulation for Open link in same pageroof lights.
  4. Placing some of the Open link in same pagerequired insulation at the roof level may result in a more practical outcome. Insulation at the roof level is effective in warm climates and significantly moderates the roof space extremes and condensation risk in cold climates.

3.12.1.3 Roof lights

Roof lights (including any associated shaft and diffuser) serving a Open link in same pagehabitable room or an interconnecting space such as a corridor, hallway, stairway or the like must—

(a)

if the Open link in same pageroof lights are not Open link in same pagerequired for compliance with Open link in same pagePart 3.8

(ii)

have an aggregate area of not more than 3% of the total Open link in same pagefloor area of the storey served; or

(b)

if the Open link in same pageroof lights are Open link in same pagerequired for compliance with Open link in same pagePart 3.8

(i)

have an area not more than 150% of the minimum area required by Open link in same pagePart 3.8.5; and

(ii)

have transparent and translucent elements, including any imperforate ceiling diffuser with—

(A)

an Open link in same pageTotal System SHGC of not more than 0.29; and

(B)

a Open link in same pageTotal System U-Value of not more than 2.9.

Table 3.12.1.2 ROOF LIGHTS — THERMAL PERFORMANCE OF TRANSPARENT AND TRANSLUCENT ELEMENTS

Roof lights shaft index (see Note 1) Constant Total area of Open link in same pageroof lights serving the room or space as a percentage of the Open link in same pagefloor area of the room or space
Not more than 2% More than 2% to not more than 3% More than 3% to not more than 4% More than 4% to not more than 5%
Less than 0.5 Total System SHGC Not more than 0.83 Not more than 0.57 Not more than 0.43 Not more than 0.34
Total System U-Value Not more than 8.5 Not more than 5.7 Not more than 4.3 Not more than 3.4
0.5 to less than 1.0 Total System SHGC Not more than 0.83 Not more than 0.72 Not more than 0.54 Not more than 0.43
Total System U-Value Not more than 8.5 Not more than 5.7 Not more than 4.3 Not more than 3.4
1.0 to less than 2.5 Total System SHGC Not more than 0.83 Not more than 0.83 Not more than 0.69 Not more than 0.55
Total System U-Value Not more than 8.5 Not more than 5.7 Not more than 4.3 Not more than 3.4
2.5 and above Total System SHGC Not more than 0.83 Not more than 0.83 Not more than 0.83 Not more than 0.83
Total System U-Value Not more than 8.5 Not more than 5.7 Not more than 4.3 Not more than 3.4

Notes:

  1. The Open link in same pageroof light shaft index is determined by measuring the distance from the centre of the shaft at the roof to the centre of the shaft at the ceiling level and dividing it by the average internal dimension of the shaft opening at the ceiling level (or the diameter for a circular shaft) in the same units of measurement.
  2. The total area of Open link in same pageroof lights is the combined area for all Open link in same pageroof lights serving the room or space.
  3. The area of a Open link in same pageroof light is the area of the roof opening that allows light to enter the building.
  4. The thermal performance of an imperforate ceiling diffuser may be included in the Open link in same pageTotal System U-Value of the Open link in same pageroof light.
  5. The total area of Open link in same pageroof lights serving the room or space as a percentage of the Open link in same pagefloor area of the room or space must not exceed 5% unless allowed by Open link in same page3.12.1.3(b).
Explanatory information:
  1. The Total System SHGC and Total System U-Values are expressed as Australian Fenestration Rating Council (AFRC) values.
  2. The Total System SHGC and Total System U-Values are for a Open link in same pageroof light with or without a ceiling diffuser. A roof light may achieve the required performance on its own or in conjunction with a ceiling diffuser.
  3. The Total System SHGC and Total System U-Values for some simple types of roof lights are shown in the table below. Smaller numbers indicate better glazing element performance. The table gives worst case assessments, which can be improved by obtaining generic or custom product assessments from suppliers, manufacturers, industry associations (including their online resources) and from competent assessors.
WORST CASE WHOLE ROOF LIGHT ELEMENT PERFORMANCE VALUES WITHOUT A CEILING DIFFUSER OR WITH A PERFORATED CEILING DIFFUSER
Translucent or transparent element description Domed panel Flat, framed panel
Total System SHGC Total System U-Values Total System SHGC Total System U-Values
Single layer clear 0.80 8.4 0.79 8.0
Single tinted 0.66 8.4 0.63 7.9
Single layer translucent ("opal") 0.57 8.4 0.56 7.9
Double layer clear 0.71 5.4 0.70 4.9

 

WORST CASE WHOLE ROOF LIGHT ELEMENT PERFORMANCE VALUES WITH AN IMPERFORATE CEILING DIFFUSER
Translucent or transparent element description Domed panel Flat, framed panel
Total System SHGC Total System U-Values Total System SHGC Total System U-Values
Single layer clear 0.72 4.3 0.71 4.2
Single tinted 0.59 4.3 0.57 4.2
Single layer translucent ("opal") 0.51 4.3 0.50 4.2
Double layer clear 0.64 3.4 0.63 3.2

3.12.1.4 External walls

(a)

Each part of an Open link in same pageexternal wall must satisfy the requirements of Open link in same pageTable 3.12.1.3a for all walls, or Open link in same pageTable 3.12.1.3b for walls with a surface density of not less than 220 kg/m2, except for—

(i)

opaque non-glazed openings such as doors (including garage doors), vents, penetrations, shutters and the like; and

(ii)

glazing unless covered by Open link in same pageTable 3.12.1.3b.

Explanatory information:

Surface density is the mass of one vertical square metre of wall.

Table 3.12.1.3a  — OPTIONS FOR EACH PART OF AN EXTERNAL WALL

Climate Zone Options
1, 2, 3, 4 and 5
  1. Achieve a minimum Open link in same pageTotal R-Value of 2.8.
  1.  
    1. Achieve a minimum Open link in same pageTotal R-Value of 2.4; and
    2. shade the Open link in same pageexternal wall of the storey with a verandah, balcony, eaves, carport or the like, which projects at a minimum angle of 15 degrees in accordance with Open link in same pageFigure 3.12.1.2.
6 and 7 Achieve a minimum Open link in same pageTotal R-Value of 2.8.
8 Achieve a minimum Open link in same pageTotal R-Value of 3.8.

 

Table 3.12.1.3b  — OPTIONS FOR EACH PART OF AN EXTERNAL WALL WITH A SURFACE DENSITY OF NOT LESS THAN 220 kg/m2

Climate Zone Options
1, 2 and 3
  1.  
    1. For a storey, other than one with another storey above, shade the wall with a verandah, balcony, eaves, carport or the like which projects at a minimum angle of 15 degrees in accordance with Open link in same pageFigure 3.12.1.2; and
    2. when the Open link in same pageexternal walls are not shaded in accordance with (i) and there is another storey above, external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for CSHGC in Open link in same page3.12.2.1 reduced by 20%; and
    3. theOpen link in same page external wall incorporates insulation with an Open link in same pageR-Value of not less than 0.5; and
    4. the lowest storey containing Open link in same pagehabitable rooms has—
      1. a concrete slab-on-ground floor; or
      2. masonry Open link in same pageinternal walls.
5
  1.  
    1. For a storey, other than one with another storey above, shade the wall with a verandah, balcony, eaves, carport or the like which projects at a minimum angle of 15 degrees in accordance with Open link in same pageFigure 3.12.1.2; and
    2. when the Open link in same pageexternal walls are not shaded in accordance with (i) and there is another storey above, external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for CSHGC in Open link in same pageTable 3.12.2.1 reduced by 15%; and
    3. theOpen link in same page external wall incorporates insulation with an Open link in same pageR-Value of not less than 0.5; and
    4. the lowest storey containing Open link in same pagehabitable rooms has—
      1. a concrete slab-on-ground floor; or
      2. masonry Open link in same pageinternal walls.
  1.  
    1. Shade the wall with a verandah, balcony, eaves, carport or the like which projects at a minimum angle of 15 degrees in accordance with Open link in same pageFigure 3.12.1.2; and
    2. external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for CSHGC in Open link in same pageTable 3.12.2.1 reduced by 15%; and
    3. the lowest storey containing Open link in same pagehabitable rooms has—
      1. a concrete slab-on-ground floor; and
      2. masonry Open link in same pageinternal walls.
4 and 6
  1.  
    1. The external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for Cu in Open link in same pageTable 3.12.2.1 reduced by 15%; and
    2. the Open link in same pageexternal wall incorporates insulation with an Open link in same pageR-Value of not less than 0.5; and
    3. the lowest storey containing Open link in same pagehabitable rooms has—
      1. a concrete slab-on-ground floor; or
      2. masonry Open link in same pageinternal walls.
  1.  The external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for Cu in Open link in same pageTable 3.12.2.1 reduced by 20%.
  1.  
    1. The Open link in same pageexternal wall incorporates insulation with an Open link in same pageR-Value of not less than 1.0; and
    2. the lowest storey containing Open link in same pagehabitable rooms has—
      1. a concrete slab-on-ground floor; and
      2. masonry Open link in same pageinternal walls.
7
  1.  
    1. The external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for Cu in Open link in same pageTable 3.12.2.1 reduced by 15%; and
    2. the Open link in same pageexternal wall incorporates insulation with an Open link in same pageR-Value of not less than 1.0.
  1.  
    1. The external Open link in same pageglazing complies with 3.12.2.1 with the applicable value for Cu in Open link in same pageTable 3.12.2.1 reduced by 20%; and
    2. the Open link in same pageexternal wall incorporates insulation with an Open link in same pageR-Value of not less than 0.5.
  1. The Open link in same pageexternal wall incorporates insulation with an Open link in same pageR-Value of not less than 1.5.
8 Achieve a minimum Open link in same pageTotal R-Value of 3.8.

 

Figure 3.12.1.2

MEASUREMENT OF A PROJECTION FOR WALL SHADING

Show Full Sized ImageFigure 3.12.1.2 MEASUREMENT OF A PROJECTION FOR WALL SHADING
Explanatory information:

Guttering can be considered as providing shading if attached to a shading projection.

(b)

A wall in Open link in same pageTable 3.12.1.3a that—

(i)

has lightweight external cladding such as weatherboards, fibre-cement or metal sheeting fixed to the metal frame; and

(ii)

does not have a wall lining or has a wall lining that is fixed directly to the metal frame (see Open link in same pageFigure 3.12.1.3(a) and Open link in same page(b)),

must have a thermal break, consisting of a material with an Open link in same pageR-Value of not less than 0.2, installed between the external cladding and the metal frame.

Explanatory information:
  1. The thermal performance of metal and timber framed walls is affected by conductive thermal bridging by the framing members and convective thermal bridging at gaps between the framing and any added bulk insulation. Metal framed walls are more prone to conductive thermal bridging than timber framed walls.
  2. Because of the high thermal conductance of metal, a thermal break is needed when a metal framing member directly connects the external cladding to the internal lining or the internal environment. The purpose of the thermal break is to ensure that the thermal performance of the metal framed wall is comparable to that of a similarly clad timber framed wall.

    A thermal break may be provided by materials such as timber battens, plastic strips or polystyrene insulation sheeting. The material used as a thermal break must separate the metal frame from the cladding and achieve the specified Open link in same pageR-Value.

    For the purposes of 3.12.1.4(b)(ii), expanded polystyrene strips of not less than 12 mm thickness and timber of not less than 20 mm thickness are deemed to achieve an R-Value of not less than 0.2.

    The Open link in same pageR-Value of the thermal break is not included when calculating the Open link in same pageTotal R-Value of the wall, if the thermal break is only applied to the metal frame, because this calculation is done for locations free of framing members.

(c)

A wall constructed in accordance with Open link in same pageFigure 3.12.1.3 is deemed to have the Open link in same pageTotal R-Value specified in that Figure if it has an airspace.

Figure 3.12.1.3 TOTAL R-VALUE FOR TYPICAL WALL CONSTRUCTION

External wall construction description Total R-Value

(a) Weatherboard

Show Full Sized ImageFigure 3.12.1.3a TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.48

(b) Fibre-cement sheet

Show Full Sized ImageFigure 3.12.1.3b TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.42

(c) Clay masonry veneer

Show Full Sized ImageFigure 3.12.1.3c TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.56

(d) Concrete blockwork masonry

Show Full Sized ImageFigure 3.12.1.3d TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.54

(e) Cavity clay masonry

Show Full Sized ImageFigure 3.12.1.3e TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.69

(f) Externally insulated clay masonry

Show Full Sized ImageFigure 3.12.1.3f TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.53

(g) Externally insulated concrete masonry

Show Full Sized ImageFigure 3.12.1.3g TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

0.46

(h) Autoclaved aerated concrete masonry

Show Full Sized ImageFigure 3.12.1.3h TYPICAL INSULATION OPTIONS FOR TYPICAL WALL CONSTRUCTION

2.42
Explanatory information:
  1. Figure 3.12.1.3 provides examples of typical types of wall construction. The additional R-Value required can be calculated by subtracting the inherent Total R-Value of the typical wall construction in Figure 3.12.1.3 from the required Total R-Value. The inherent Total R-Value of the typical wall construction has been arrived at by adding together the R-Values for outdoor air film, wall cladding or veneer, wall cavity or airspace, internal lining and internal air film. Where a cavity or airspace is filled the Total R-Value should be reduced by 0.17 to take account of the loss of the cavity or airspace.
  2. Reflective insulation with one reflective surface having an emittance and direction as indicated, is considered to achieve the following R-Values when used in conjunction with the Total R-Value of a wall construction, as described in Figure 3.12.1.3. The actual added by reflective insulation should be determined for each product in accordance with the standard prescribed in 3.12.1.1(a), which takes into consideration factors such as the number of adjacent airspaces, dimensions of the adjacent airspace, whether the airspace is ventilated and the presence of an anti-glare coating.
Wall construction Reflective airspace details R-Value added by reflective insulation
Concrete or masonry with internal plasterboard on battens One 20 mm reflective airspace located between Open link in same pagereflective insulation (of not more than 0.05 emittance inwards) and plasterboard 0.48
External wall cladding (70 mm timber frame with internal lining) One 70 mm reflective airspace located between Open link in same pagereflective insulation (of not more than 0.05 emittance inwards) and plasterboard 0.43
Masonry veneer (70 mm timber frame with internal lining)
  1. One 70 mm reflective airspace located between Open link in same pagereflective insulation and plasterboard; and
  2. One 25 mm anti-glare airspace located between Open link in same pagereflective insulation (of not more than 0.2 emittance outwards) and masonry
0.95
Cavity masonry
  1. No airspace between the Open link in same pagereflective insulation and the inner leaf of masonry; and
  2. One 35 mm anti-glare airspace located between Open link in same pagereflective insulation (of not more than 0.2 emittance outwards) and the outer leaf of masonry
0.50
  1. For further information on Open link in same pagereflective insulation, refer to the explanatory information following Figure 3.12.1.1.
  2. Walls with a surface density of 220 kg/m2 or more are deemed to achieve acceptable levels of thermal performance in certain Open link in same pageclimate zones due to their ability to store heat and therefore slow the heat transfer through the building Open link in same pagefabric. These walls are defined by surface density (kg/m2), which is the mass of one vertical square metre of wall, in order to reduce the complexity when measuring the mass of walls with voids.

    The following are examples of some typical wall constructions that achieve a surface density of 220 kg/m2:

    1. Two leaves each of 90 mm thick or greater clay or concrete masonry.
    2. 140 mm thick or greater dense-weight hollow concrete or clay blocks with—
      1. 10 mm plasterboard or render; and
      2. at least one concrete grouted horizontal bond beam; and
      3. vertical cores filled with concrete grout at centres not exceeding 1000 mm.
    3. 140 mm thick or greater concrete wall panels and dense-weight hollow concrete or clay blocks with all vertical cores filled with concrete grout.
    4. 190 mm thick or greater dense-weight hollow concrete or clay blocks with—
      1. at least one concrete grouted horizontal bond beam; and
      2. vertical cores filled with concrete grout at centres not exceeding 1800 mm.
    5. Earth-wall construction with a minimum wall thickness of 200 mm.

3.12.1.5 Floors

(a)

A suspended floor, other than an intermediate floor in a building with more than one storey—

Table 3.12.1.4 SUSPENDED FLOOR – MINIMUM TOTAL R-VALUE

Climate Zone 1 2 3 4 5 6 7 8
  Direction of heat flow
  Upwards Downwards
Minimum Total R-Value 1.5 1.0 1.5 2.25 1.0 2.25 2.75 3.25
Note: For an enclosed perimeter treatment, the underfloor airspace and its enclosure may be included in the Open link in same pageTotal R-Value calculation.
(ii)

with an in-slab or in-screed heating or cooling system, must be insulated—

(A)

around the vertical edge of its perimeter with insulation having an Open link in same pageR-Value of not less than 1.0; and

(B)

underneath the slab with insulation having an Open link in same pageR-Value of not less than 2.0 which may include insulation installed to meet the requirements of Open link in same page (i); and

(iii)

that is enclosed beneath, must have a barrier to prevent convection installed below floor level between the airspace under the floor and any wall Open link in same pagecavities.

Explanatory information:
  1. An enclosed perimeter treatment means that the airspace under the floor is enclosed between ground and floor level by walls which have only the Open link in same pagerequired subfloor vents.
  2. The barrier Open link in same pagerequired by 3.12.1.5(a)(iii) could be an imperforate flashing.
  3. Specific solutions for concrete slab and timber floors can be found in documents and online resources prepared by industry associations and product suppliers.
(b)

A floor is deemed to have the Open link in same pageTotal R-Value specified in Open link in same pageTable 3.12.1.5.

Table 3.12.1.5 TOTAL R-VALUE FOR TYPICAL SUSPENDED FLOOR CONSTRUCTION

Enclosure and height of floor Direction of heat flow Open link in same pageTotal R-Value
Cavity masonry 190 mm concrete masonry Single skin masonry 9 mm fibre-cement sheet
(a)  Suspended timber floor
Enclosed - not more than 0.6 m high Upwards 1.00 0.93 0.88 0.77
Downwards 1.11 1.06 1.01 0.90
Enclosed - more than 0.6 m but to not more than 1.2 m high Upwards 0.86 0.81 0.76 0.65
Downwards 1.00 0.94 0.89 0.77
Enclosed - more than 1.2 m to not more than 2.4 m high Upwards 0.76 0.72 0.67 0.57
Downwards 0.89 0.84 0.79 0.69
Unenclosed Upwards 0.39
Downwards 0.51
(b)  Suspended concrete floor
Enclosed - not more than 0.6 m high Upwards 0.93 0.88 0.83 0.72
Downwards 1.06 1.01 0.96 0.85
Enclosed - more than 0.6 m but to not more than 1.2 m high Upwards 0.81 0.76 0.71 0.60
Downwards 0.94 0.89 0.84 0.72
Enclosed - more than 1.2 m to not more than 2.4 m high Upwards 0.71 0.67 0.62 0.52
Downwards 0.84 0.79 0.74 0.64
Unenclosed Upwards 0.34
Downwards 0.46

Notes:

  1. The height of the floor is measured from ground surface to the underside of the floor or the insulation.
  2. For the purposes of calculating the Open link in same pageTotal R-Value of a floor, the Open link in same pageR-Value attributable to an in-slab or in-screed heating or cooling system is ignored.
Open link in same pageReflective insulation
Explanatory information:
  1. Table 3.12.1.5 provides examples of the inherent Total R-Values of enclosed and unenclosed suspended floors of two typical types of construction. Any added R-Value can be calculated by subtracting the inherent R-Value of the typical construction in Table 3.12.1.5 from the Open link in same pagerequired Total R-Value in Table 3.12.1.4.
  2. Any non-reflective building membrane fixed between or under floor joists is considered to add an R-Value of 0.2 to the Total R-Value of the base construction described in Table 3.12.1.5. Open link in same pageReflective insulation will achieve a higher value which will need to be determined for each product in accordance with AS/NZS 4859.1. Typically, a reflective building membrane attached beneath the floor joists of an unenclosed floor, with a single bright side facing upwards to a 90 mm airspace, can add an R-Value of 0.43 for heat flow upwards and 1.32 for heat flow downwards. Double sided Open link in same pagereflective insulation with a 90 mm airspace installed under an enclosed floor can add an R-Value of 0.55 for heat flow upwards and 1.97 for heat flow downwards. Both examples allow for dust on the upper surface in accordance with AS/NZS 4859.1.
  3. A reflective or non-reflective building membrane should be installed with due consideration of potentially damaging condensation in some Open link in same pageclimate zones and associated interaction with adjoining building materials.
  4. For further information on reflective insulation, refer to the explanatory information accompanying Figure 3.12.1.1.
(c)

A concrete slab-on-ground—

(i)

with an in-slab or in-screed heating or cooling system, must have insulation with an Open link in same pageR-Value of not less than 1.0, installed around the vertical edge of its perimeter; and

(ii)

when in Open link in same pageclimate zone 8, must be insulated—

(A)

around the vertical edge of its perimeter with insulation having an Open link in same pageR-Value of not less than 1.0; and

(B)

underneath the slab with insulation having an Open link in same pageR-Value of not less than 2.0.

(d)

Insulation Open link in same pagerequired by Open link in same page(c)(i) and Open link in same page(c)(ii)(A) must—

(i)

be water resistant; and

(ii)

be continuous from the adjacent finished ground level—

(A)

to a depth of not less than 300 mm; or

(B)

for at least the full depth of the vertical edge of the concrete slab-on-ground (see Open link in same pageFigure 3.12.1.4).

(e)

The requirements of Open link in same page(a)(ii), and Open link in same page(c)(i) do not apply to an in-screed heating or cooling system used solely in a bathroom, amenity area or the like.

Explanatory information:

3.12.1.5(e) provides an exemption for an in-screed heating or cooling system used solely in bathrooms, amenity areas and the like, as these are typically small areas.

Figure 3.12.1.4

INSULATION OF SLAB EDGE

Show Full Sized ImageFigure 3.12.1.4 INSULATION OF SLAB EDGE
Explanatory information:

Care should be taken to ensure that the type of termite management system selected is compatible with the slab edge insulation.

3.12.1.6 Attached Class 10a buildings

A Class 10a building attached to a Class 1 building must—

(a)

have an external Open link in same pagefabric that achieves the Open link in same pagerequired level of thermal performance for a Class 1 building; or

(b)

be separated from the Class 1 building with construction having the Open link in same pagerequired level of thermal performance for the Class 1 building; or

(c)

in Open link in same pageclimate zone 5—

(i)

be enclosed with masonry walls other than where there are doors and Open link in same pageglazing; and

(ii)

be separated from the Class 1 building with a masonry wall that extends to the ceiling or roof; and

(iii)

achieve a Open link in same pageTotal R-Value in the roof equivalent to that Open link in same pagerequired by Open link in same pageTable 3.12.1.1 for the Class 1 building; and

(iv)

not have a garage door facing the east or west orientation other than if the Class 1 building Open link in same pageglazing complies with 3.12.2.1 with the applicable value for CSHGC in Open link in same pageTable 3.12.2.1 reduced by 15%.

Explanatory information:

The attachment of a Class 10a building, such as a garage, glasshouse, solarium, pool enclosure or the like should not compromise the thermal performance of the Class 1 building. In addition, the Class 10a building may be insulated and so assist the Class 1 building achieve the Open link in same pagerequired thermal performance.

The following are examples of a Class 1 building with an attached Class 10a garage.

In Open link in same page(a), the thermal performance Open link in same pagerequired for the Class 1 building may be achieved by the walls and floor of the Class 1 building as if the Class 10a garage is an under floor space with an enclosed perimeter.

In Open link in same page(b), the thermal performance Open link in same pagerequired for the Class 1 building may be achieved by the outside walls and floor of the Class 10a garage.

In Open link in same page(c), in Open link in same pageclimate zone 5, the thermal performance of the Class 1 building may be achieved by ensuring that the roof of the Class 10a building satisfies Open link in same pageTable 3.12.1.1 and the walls are of masonry construction.