(1) Where required, insulation must comply with AS/NZS 4859.1 and be installed so that it—
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
forms a continuous barrier with ceilings, walls, bulkheads, floors or the like that inherently contribute to the thermal barrier; and
does not affect the safe or effective operation of a domestic service or fitting.
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.
To form a continuous barrier, insulation should be placed in gaps between window and door jambs, heads and sills, and the adjoining wall framing unless a gap is otherwise required. This may need to be compressible to allow for movement between members.
Explanatory information: Safety of domestic services
Care should be taken when installing insulation to ensure that it does not interfere with the safety or performance of domestic 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.
Explanatory information: Compression of insulation
The R-Value of insulation, including insulation used to mitigate thermal bridging, is reduced if it is compressed. The allocated space for insulation must therefore allow the insulation to be installed so that it maintains its correct thickness to achieve the product’s stated R-Value. Otherwise the R-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 rigid boards, may be necessary to ensure that the insulation achieves its requiredR-Value.
Explanatory information: Installation of reflective insulation
For reflective insulation and the adjoining airspace to achieve its tested R-Value, the airspace needs to be a certain width. This width varies depending on the particular type of reflective insulation. The R-Value also depends on the orientation of the insulation.
Where reflective insulation also acts as a vapour barrier or sarking, both a minimum overlap and taping may be necessary.
has metal sheet roofing directly fixed to metal purlins, metal rafters or metal battens; and
does not have a ceiling lining or has a ceiling lining fixed directly to those metal purlins, metal rafters or metal battens,
must have a thermal break, consisting of a material with an R-Value of greater than or equal to 0.2, installed between the metal sheet roofing and its supporting metal purlins, metal rafters or metal battens.
(2) (1) does not apply to roofs constructed using insulated sandwich panels.
NCC Title
Roofs and ceilings
NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
Roofs and ceilings
NCC ID
_e8e6ef98-88b5-4742-8159-22321330004f
(1) Roof and ceiling insulation must achieve the minimum R-Value—
(3) The thermal bridging in a metal-framed roof must be addressed as follows—
for a pitched roof with a horizontal ceiling—
achieving the Total R-Value in Table 13.2.3s, calculated using a method that accounts for the effects of thermal bridging; or
increasing the R-Value of the insulation between the ceiling frames by R0.5 more than the R-Value derived from (1); or
adding a continuous ceiling insulation layer with a minimum R-Value of R0.13 above or below the ceiling joists or the bottom chords of the trusses; or
achieving the required ceiling R-Value derived from (1) by stacking two layers of insulation immediately on top of each other, such that the top layer is orientated to cover the ceiling joists or bottom chords of the trusses and has an R-Value of at least R0.5; or
for a flat, skillion or cathedral roof—
achieving the Total R-Value in Table 13.2.3t, calculated using a method that accounts for the effects of thermal bridging; or
(5) Where, for operational or safety reasons, the area of ceiling insulation required is reduced, the loss of insulation must be compensated for in accordance with Table 13.2.3w.
(6) Where the ceiling insulation required by (1) to (5) has an R-Value—
greater than R3.0 and less than or equal to R4.5, it may be reduced to R3.0 within 450 mm of an external wall; or
greater than R4.5, it may be reduced to R3.0 within 450 mm of an external wall, provided all other required ceiling insulation is increased by R0.5.
(7) A roof that—
has metal sheet roofing directly fixed to metal purlins, metal rafters or metal battens; and
does not have a ceiling lining or has a ceiling lining fixed directly to those metal purlins, metal rafters or metal battens,
must have a thermal break, consisting of a material with an R-Value of greater than or equal to 0.2, installed between the metal sheet roofing and its supporting metal purlins, metal rafters or metal battens.
(8) The requirements of (1) to (7) do not apply to roofs constructed using insulated sandwich panels.
(9) Roofs constructed using insulated sandwich panels must achieve the minimum Total R-Value in Table 13.2.3x.
(10) In climate zones 1 to 5, the solar absorptance of the upper surface of a roof must not be more than 0.64.
Table 13.2.3a Pitched roof with horizontal ceiling – minimum R-Value for ceiling insulation: climate zone 1 – single storey dwelling
The Total R-Value calculation only includes the ceiling frame, insulation and ceiling lining. It is not to include internal air films, roof space or roof lining.
Minimum ceiling Total R-Values are in-situ values. They account for compression of insulation.
Table 13.2.3t Metal-framed flat, skillion or cathedral roof – minimum Total R-Value to account for thermal bridging
Direction of heat flow must be determined in accordance with Table 13.2.3v.
X = not permitted.
Explanatory information: Table 13.2.3w
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.
Note that 13.2.3(5) does not require an increase in ceiling insulation for roof lights.
Placing some of the required 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. Note that Part 10.8 contains specific provisions for condensation.
The effect of thermal bridging through repeating framing elements such as ceiling joists and the bottom chord of ceiling trusses must be considered when calculating the Total R-Value of metal-framed roofs. Other types of thermal bridges may be calculated if considered significant.
Roof lights (including any associated shaft and diffuser) serving a habitable room or an interconnecting space such as a corridor, hallway, stairway or the like must have—
a total area of not more than 5% of the floor area of the room or space served; and
transparent and translucent elements, including any imperforate ceiling diffuser, with a combined performance of—
Total area of roof lights up to 3.5% of the floor area of the room or space
Total area of roof lights more than 3.5% and up to 5% of the floor area of the room or space
< 1.0
≤ 0.45
≤ 0.29
≥ 1.0 to < 2.5
≤ 0.51
≤ 0.33
≥ 2.5
≤ 0.76
≤ 0.49
Table Notes
The roof 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.
The area of a roof light is the area of the roof opening that allows light to enter the building. The total area of roof lights is the combined area for all roof lights serving the room or space.
(1) A metal-framed wall that forms part of the building envelope must have a thermal break, consisting of a material with an R-Value of not less than R0.2, installed at all points of contact between the external cladding and the metal frame if the wall—
does not have a wall lining or has a wall lining that is fixed directly to the metal frame; and
is clad with weatherboards, fibre-cement or the like, or metal sheeting fixed to the metal frame.
(2) The requirements of (1) do not apply to walls constructed using insulated sandwich panels.
Explanatory information
A lightweight wall has no high thermal mass cladding on the outside or lining on the inside. Typically, this would represent a framed wall, clad externally with timber weatherboards, fibre-cement sheet, metal or autoclaved aerated concrete.
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. For the purposes of NSW 13.2.5(1)(b), expanded polystyrene strips greater than or equal to 12 mm thickness and timber greater than or equal to 20 mm thickness are deemed to achieve an R-Value greater than or equal to 0.2.
Many reflective insulation products that use perforations to increase their vapour permeance are not suitable for use behind vertical or diagonally orientated timber cladding boards, where required by clause 7.5.2 of the ABCB Housing Provisions, or behind open jointed or unsealed cladding systems.
NCC Title
External walls
NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
External walls
NCC ID
_d974d212-c849-4678-9101-ec158fbf8c7c
(1) Except for the external wall of a sub-floor space below a suspended floor and lightweight wall construction, wall insulation must have a minimum R-Value—
(5) A metal-framed wall that forms part of the building envelope must have a thermal break, consisting of a material with an R-Value of not less than R0.2, installed at all points of contact between the external cladding and the metal frame if the wall—
does not have a wall lining or has a wall lining that is fixed directly to the metal frame; and
is clad with weatherboards, fibre-cement or the like, or metal sheeting fixed to the metal frame.
(6) The requirements of (5) do not apply to walls constructed using insulated sandwich panels.
R-Values listed are for the labelled, declared R-Value of insulation.
X = not permitted.
Reflective = reflective insulation with an airspace with a minimum width of at least 20 mm. The surface emittance of the reflective surface facing the airspace must be a maximum of 0.1, where the airspace is exposed to the sun during construction to reduce glare (an outward facing surface), or 0.05 if not exposed to the sun (an inward facing surface).
This table shows wall heights for single storey dwellings. For two storey (or more) dwellings with a wall height up to 2.4 m, add R0.5 to the R-Values given in this Table. For two storey (or more) dwellings with a wall height greater than 2.4 m, add R1.0.
R-Values listed are for the labelled, declared R-Value of insulation.
X = not permitted.
Reflective = reflective insulation with an airspace with a minimum width of at least 20 mm. The surface emittance of the reflective surface facing the airspace must be a maximum of 0.1 where the airspace is exposed to the sun during construction to reduce glare (an outward facing surface), or 0.05 of not exposed to the sun (an inward facing surface).
This Table shows wall heights for single storey dwellings. For two storey (or more) dwellings with a wall height up to 2.4 m, add R0.5 to R-Values from this Table. For two storey (or more) dwellings with a wall height greater than 2.4 m, add R1.0.
R-Values listed are for the labelled, declared R-Value of insulation.
X = not permitted.
This Table shows wall heights for single storey dwellings. For two storey (or more) dwellings with a wall height of up to 2.4 m add R0.4 to the R-Values from this Table. For two storey (or more) dwellings with a wall height greater than 2.4 m, add R0.8.
R-Values listed are for the labelled, declared R-Value for insulation.
X = not permitted.
Reflective = reflective insulation with an airspace with a minimum width of at least 20 mm. The surface emittance of the reflective surface facing the airspace must be a maximum 0.1, where the airspace is exposed to the sun during construction to reduce glare (an outward facing surface), or 0.05 if not exposed to the sun (an inward facing surface).
This Table shows wall heights for single storey dwellings. For two storey (or more) dwellings with a wall height up to 2.4 m, add R1.0 to the R-Values given in this Table. For two storey (or more) dwellings with a wall height greater than 2.4 m, add R1.5.
R-Values listed are for the labelled, declared R-Value of insulation.
X = not permitted.
This Table shows wall heights for single storey dwellings. For two storey (or more) dwellings, add R0.25 to the R-Values given in this Table, to a maximum R-Value of R1.44.
R-Values listed are for the labelled, declared R-Value of insulation.
X = not permitted.
This Table shows wall heights for single storey dwellings. For two storey (or more) dwellings with a wall height up to 2.4 m, add R0.5 to the R-Values given in this Table. For two storey (or more) dwellings with a wall height greater than 2.4 m, add R1.0. In both cases, the maximum insulation level must be not more than R2.7, or R3.1 if there is a reflective airspace.
Table 13.2.5p Concrete block walls with internal lining fixed to a metal frame: minimum Total R-Value to account for thermal bridging
Either install reflective insulation outside the frame to create a minimum 20 mm reflective airspace between frame and cladding, or increase insulation between frames by R0.5.
>1.5
Either install reflective insulation outside the frame to create a minimum 20 mm reflective airspace between frame and cladding, or add a layer of continuous insulation with an R-Value of at least R0.30 on the inside or the outside of the frame.
Table Notes
Minimum R-Values are in-situ values. They account for compression of insulation.
The surface emittance of a reflective surface facing an airspace must be a maximum of 0.1.
Either install reflective insulation outside the frame to a minimum 20 mm reflective airspace between the frame and veneer, or add a layer of continuous insulation with an R-Value of at least R0.30 on the inside or the outside of the frame.
Table Notes
Minimum R-Values are in-situ values. They account for compression of insulation.
The surface emittance of a reflective surface facing an airspace must be a maximum of 0.1.
Explanatory information
A lightweight wall has no high thermal mass cladding on the outside or lining on the inside. Typically, this would represent a framed wall, clad externally with timber weatherboards, fibre-cement sheet, metal or autoclaved aerated concrete.
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. For the purposes of 13.2.5(5)(b), expanded polystyrene strips greater than or equal to 12 mm thickness and timber greater than or equal to 20 mm thickness are deemed to achieve an R-Value greater than or equal to 0.2.
Many reflective insulation products that use perforations to increase their vapour permeance are not suitable for use behind vertical or diagonally orientated timber cladding boards, where required by clause 7.5.2 of the ABCB Housing Provisions, or behind open jointed or unsealed cladding systems.
(1) A concrete slab-on-ground with an in-slab or in-screed heating or cooling system, must have insulation with an R-Value greater than or equal to 1.0, installed around the vertical edge of its perimeter.
be continuous from the adjacent finished ground level—
to a depth of greater than or equal to 300 mm; or
for at least the full depth of the vertical edge of the concrete slab-on-ground (see Figure 13.2.6).
(3) The requirements of (1) do not apply to an in-screed heating or cooling system used solely in a bathroom, amenity area or the like.
Explanatory information
NSW 13.2.6(3) 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.
Care should be taken to ensure that the type of termite management system selected is compatible with the slab edge insulation.
NCC Title
Floors and subfloor walls
NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
Floors and subfloor walls
NCC ID
_889dd04d-070b-48b6-aa4d-b90e142d9117
(1) Floor insulation, where the floor is over an unenclosed space, must achieve the minimum R-Value in accordance with Table 13.2.6a.
(2) Floor and subfloor insulation, where the floor is over an enclosed subfloor space, must—
(4) A concrete slab-on-ground with an in-slab or in-screed heating or cooling system, must have insulation with an R-Value greater than or equal to 1.0, installed around the vertical edge of its perimeter.
The Total R-Value can be adjusted using area weightings where there is a combination of floor coverings. Invert the Total R-Value for each floor type before applying area weightings.
The Total R-Value for the floor plane only includes the floor frame, insulation, flooring and floor coverings. It does not include the internal air film, subfloor airspace, subfloor walls or external air film.
Minimum Total R-Values are in-situ values. They account for compression of insulation.
Direction of heat flow must be determined in accordance with Table 13.2.6k.
For 13.2.6(3) the effect of thermal bridging through repeating framing elements must be considered when calculating the Total R-Value of metal-framed floors. Other types of thermal bridges may be calculated if considered significant.
13.2.6(7) 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.
Care should be taken to ensure that the type of termite management system selected is compatible with the slab edge insulation.
A Class 10a building attached to a Class 1 building must—
have an external fabric that achieves the required level of thermal performance for a Class 1 building; or
be separated from the Class 1 building with construction having the required level of thermal performance for the Class 1 building.
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 required thermal performance.
Explanatory Figure 13.2.7 below depicts examples of a Class 1 building with an attached Class 10a garage.