Part J4 Building fabric
Introduction to this Part
This Part contains Deemed-to-Satisfy Provisions for compliance with Part J1. It sets out provisions for the building envelope including roofs, ceilings, roof lights, walls, glazing and floors.
Notes
From 1 May 2023 to 30 September 2023 Section J of NCC 2019 Volume One Amendment 1 may apply instead of Section J of NCC 2022 Volume One. From 1 October 2023 Section J of NCC 2022 Volume One applies.
Notes: New South Wales Section J Energy Efficiency
- For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Single Dwelling or Multi Dwelling Certificate issued under Version 3.0 or earlier, NSW Section J of NCC 2019 Volume One Amendment 1 applies.
- For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Single Dwelling or Multi Dwelling Certificate issued under Version 4.0 or later, Section J of NCC 2022 Volume One applies.
- For a Class 2 building or a Class 4 part of a building, where a relevant development consent or an application for a complying development certificate requires compliance with a BASIX Alterations and Additions Certificate, NSW Section J of NCC 2019 Volume One Amendment 1 applies.
- For a Class 3 building or Class 5 to 9 building:
- From 1 May 2023 to 30 September 2023 NSW Section J of NCC 2019 Volume One Amendment 1 may apply instead of Section J of NCC 2022 Volume One.
- From 1 October 2023 Section J of NCC 2022 Volume One applies.
Notes: Tasmania Section J Energy Efficiency
In Tasmania, for a Class 2 building and Class 4 part of a building, Section J is replaced with Section J of BCA 2019 Amendment 1.
Deemed-to-Satisfy Provisions
J4D1
Deemed-to-Satisfy Provisions
2019: J1.0
- J2D2; and
- J3D2 to J3D15; and
- J4D2 to J4D7; and
- J5D2 to J5D8; and
- J6D2 to J6D13; and
- J7D2 to J7D9; and
- J8D2 to J8D4; and
- J9D2 to J9D5.
NSW J4D1 Deemed-to-Satisfy Provisions2019: J1.0
- NSW J2D2; and
J4D2
Application of Part
2019: J1.1
Application of Part
The Deemed-to-Satisfy Provisions of this Part apply to building elements forming the envelope of a Class 2 to 9 building other than J4D3(5), J4D4, J4D5, J4D6 and J4D7 which do not apply to a Class 2 sole-occupancy unit or a Class 4 part of a building.
J4D3
Thermal construction — general
2019: J1.2
- abuts or overlaps adjoining insulation other than at supporting members such as studs, noggings, joists, furring channels and the like where the insulation must be 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 service or fitting.
- the necessary airspace to achieve the required R-Value between a reflective side of the reflective insulation and a building lining or cladding; and
- the reflective insulation closely fitted against any penetration, door or window opening; and
- the reflective insulation adequately supported by framing members; and
- each adjoining sheet of roll membrane being—
- overlapped not less than 50 mm; or
- taped together.
- it maintains its position and thickness, other than where it is compressed between cladding and supporting members, water pipes, electrical cabling or the like; and
- in a ceiling, where there is no bulk insulation or reflective insulation in the wall beneath, it overlaps the wall by not less than 50 mm.
- calculated in accordance with AS/NZS 4859.2 for a roof or floor; or
- determined in accordance with Specification 37 for wall-glazing construction; or
- determined in accordance with Specification 39 or Section 3.5 of CIBSE Guide A for soil or sub-floor spaces.
Notes
Where required is deemed to refer to “Where a development consent specifies that insulation is to be provided as part of the development.”.
Thermal construction—general
- abuts or overlaps adjoining insulation other than at supporting members such as studs, noggings, joists, furring channels and the like where the insulation must be 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 service or fitting.
- the necessary airspace to achieve the required R-Value between a reflective side of the reflective insulation and a building lining or cladding; and
- the reflective insulation closely fitted against any penetration, door or window opening; and
- the reflective insulation adequately supported by framing members; and
- each adjoining sheet of roll membrane being—
- overlapped not less than 50 mm; or
- taped together.
- it maintains its position and thickness, other than where it is compressed between cladding and supporting members, water pipes, electrical cabling or the like; and
- in a ceiling, where there is no bulk insulation or reflective insulation in the wall beneath, it overlaps the wall by not less than 50 mm.
- calculated in accordance with AS/NZS 4859.2 for a roof or floor; or
- determined in accordance with Specification 37 for wall-glazing construction; or
- determined in accordance with Specification 39 or Section 3.5 of CIBSE Guide A for soil or sub-floor spaces.
J4D4
Roof and ceiling construction
2019: J1.3
- in climate zones 1, 2, 3, 4 and 5, R3.7 for a downward direction of heat flow; and
- in climate zone 6, R3.2 for a downward direction of heat flow; and
- in climate zone 7, R3.7 for an upward direction of heat flow; and
- in climate zone 8, R4.8 for an upward direction of heat flow.
J4D5
Roof lights
2019: J1.4
Roof lights 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—
- for Total system SHGC, in accordance with Table J4D5; and
- for Total system U-Value, not more than U3.9.
Roof light shaft index Note 1 | 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.
J4D6
Walls and glazing
2019: J1.5
- for a Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area, U2.0; and
- for a Class 3 or 9c building or a Class 9a ward area—
- in climate zones 1, 3, 4, 6 or 7, U1.1; or
- in climate zones 2 or 5, U2.0; or
- in climate zone 8, U0.9.
- where the wall is less than 80% of the area of the wall-glazing construction, R1.0; or
- where the wall is 80% or more of the area of the wall-glazing construction, the value specified in NSW Table J4D6a.
- for a Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area, the values specified in NSW Table J4D6b; and
- for a Class 3 or 9c building or a Class 9a ward area, the values specified in NSW Table J4D6c.
Climate zone | Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area | Class 3 or 9c building or Class 9a ward area |
---|---|---|
1 | 2.4 | 3.3 |
2 | 1.4 | 1.4 |
3 | 1.4 | 3.3 |
4 | 1.4 | 2.8 |
5 | 1.4 | 1.4 |
6 | 1.4 | 2.8 |
7 | 1.4 | 2.8 |
8 | 1.4 | 3.8 |
Climate zone | Eastern aspect solar admittance | Northern aspect solar admittance | Southern aspect solar admittance | Western aspect solar admittance |
---|---|---|---|---|
1 | 0.12 | 0.12 | 0.12 | 0.12 |
2 | 0.13 | 0.13 | 0.13 | 0.13 |
3 | 0.16 | 0.16 | 0.16 | 0.16 |
4 | 0.13 | 0.13 | 0.13 | 0.13 |
5 | 0.13 | 0.13 | 0.13 | 0.13 |
6 | 0.13 | 0.13 | 0.13 | 0.13 |
7 | 0.13 | 0.13 | 0.13 | 0.13 |
8 | 0.2 | 0.2 | 0.42 | 0.36 |
Climate zone | Eastern aspect solar admittance | Northern aspect solar admittance | Southern aspect solar admittance | Western aspect solar admittance |
---|---|---|---|---|
1 | 0.07 | 0.07 | 0.10 | 0.07 |
2 | 0.10 | 0.10 | 0.10 | 0.10 |
3 | 0.07 | 0.07 | 0.07 | 0.07 |
4 | 0.07 | 0.07 | 0.07 | 0.07 |
5 | 0.10 | 0.10 | 0.10 | 0.10 |
6 | 0.07 | 0.07 | 0.07 | 0.07 |
7 | 0.07 | 0.07 | 0.08 | 0.07 |
8 | 0.08 | 0.08 | 0.08 | 0.08 |
Walls and glazing
- for a Class 2 common area, a Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area, U2.0; and
- for a Class 3 or 9c building or a Class 9a ward area—
- in climate zones 1, 3, 4, 6 or 7, U1.1; or
- in climate zones 2 or 5, U2.0; or
- in climate zone 8, U0.9.
- where the wall is less than 80% of the area of the wall-glazing construction, R1.0; or
- where the wall is 80% or more of the area of the wall-glazing construction, the value specified in Table J4D6a.
- for a Class 2 common area, a Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area, the values specified in Table J4D6b; and
- for a Class 3 or 9c building or a Class 9a ward area, the values specified in Table J4D6c.
Climate zone | Class 2 common area, Class 5, 6, 7, 8 or 9b building or a Class 9a building other than a ward area | Class 3 or 9c building or Class 9a ward area |
---|---|---|
1 | 2.4 | 3.3 |
2 | 1.4 | 1.4 |
3 | 1.4 | 3.3 |
4 | 1.4 | 2.8 |
5 | 1.4 | 1.4 |
6 | 1.4 | 2.8 |
7 | 1.4 | 2.8 |
8 | 1.4 | 3.8 |
Climate zone | Eastern aspect solar admittance | Northern aspect solar admittance | Southern aspect solar admittance | Western aspect solar admittance |
---|---|---|---|---|
1 | 0.12 | 0.12 | 0.12 | 0.12 |
2 | 0.13 | 0.13 | 0.13 | 0.13 |
3 | 0.16 | 0.16 | 0.16 | 0.16 |
4 | 0.13 | 0.13 | 0.13 | 0.13 |
5 | 0.13 | 0.13 | 0.13 | 0.13 |
6 | 0.13 | 0.13 | 0.13 | 0.13 |
7 | 0.13 | 0.13 | 0.13 | 0.13 |
8 | 0.2 | 0.2 | 0.42 | 0.36 |
Climate zone | Eastern aspect solar admittance | Northern aspect solar admittance | Southern aspect solar admittance | Western aspect solar admittance |
---|---|---|---|---|
1 | 0.07 | 0.07 | 0.10 | 0.07 |
2 | 0.10 | 0.10 | 0.10 | 0.10 |
3 | 0.07 | 0.07 | 0.07 | 0.07 |
4 | 0.07 | 0.07 | 0.07 | 0.07 |
5 | 0.10 | 0.10 | 0.10 | 0.10 |
6 | 0.07 | 0.07 | 0.07 | 0.07 |
7 | 0.07 | 0.07 | 0.08 | 0.07 |
8 | 0.08 | 0.08 | 0.08 | 0.08 |
J4D7
Floors
2019: J1.6
- in climate zone 8; or
- a Class 3, Class 9a ward area or Class 9b building in climate zone 7 that has a floor area to floor perimeter ratio of less than or equal to 2.
- is a concrete slab-on-ground in climate zone 8; or
- has an in-slab or in-screed heating or cooling system, except where used solely in a bathroom, amenity area or the like.
- be water resistant; and
- be continuous from the adjacent finished ground level—
- to a depth not less than 300 mm; or
- for the full depth of the vertical edge of the concrete slab-on-ground.
Location | Climate zone 1— upwards heat flow | Climate zones 2 and 3 — upwards and downwards heat flow | Climate zones 4, 5, 6 and 7 — downwards heat flow | Climate zone 8 — downwards heat flow |
---|---|---|---|---|
A floor without an in-slab heating or cooling system | 2.0 | 2.0 | 2.0 | 3.5 |
A floor with an in-slab heating or cooling system | 3.25 | 3.25 | 3.25 | 4.75 |
Table Notes
For the purpose of calculating the Total R-Value of a floor, the sub-floor and soil R-Value must be calculated in accordance with Specification 39 or Section 3.5 of CIBSE Guide A.