Part J4 Building fabric

(1) Where a Deemed-to-Satisfy Solution is proposed, Performance Requirements J1P1 to J1P4 are satisfied by complying with—

1. J2D2; and
2. J3D2 to J3D15; and
3. J4D2 to J4D7; and
4. J5D2 to J5D8; and
5. J6D2 to J6D13; and
6. J7D2 to J7D9; and
7. J8D2 to J8D4; and
8. J9D2 to J9D5.

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

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.

(1) Where required, insulation must comply with AS/NZS 4859.1 and be installed so that it—

1. 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
2. forms a continuous barrier with ceilings, walls, bulkheads, floors or the like that inherently contribute to the thermal barrier; and
3. does not affect the safe or effective operation of a service or fitting.

(2) Where required, reflective insulation must be installed with—

1. the necessary airspace to achieve the required R-Value between a reflective side of the reflective insulation and a building lining or cladding; and
2. the reflective insulation closely fitted against any penetration, door or window opening; and
3. the reflective insulation adequately supported by framing members; and
4. each adjoining sheet of roll membrane being—
   1. overlapped not less than 50 mm; or
   2. taped together.

(3) Where required, bulk insulation must be installed so that—

1. 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
2. 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.

(4) Roof, ceiling, wall and floor materials, and associated surfaces are deemed to have the thermal properties listed in Specification 36.

(5) The required Total R-Value and Total System U-Value, including allowance for thermal bridging, must be—

1. calculated in accordance with AS/NZS 4859.2 for a roof or floor; or
2. determined in accordance with Specification 37 for wall-glazing construction; or
3. determined in accordance with Specification 39 or Section 3.5 of CIBSE Guide A for soil or sub-floor spaces.

(1) A roof or ceiling must achieve a Total R-Value greater than or equal to—

1. in climate zones 1, 2, 3, 4 and 5, R3.7 for a downward direction of heat flow; and
2. in climate zone 6, R3.2 for a downward direction of heat flow; and
3. in climate zone 7, R3.7 for an upward direction of heat flow; and
4. in climate zone 8, R4.8 for an upward direction of heat flow.

(2) In climate zones 1, 2, 3, 4, 5, 6 and 7, the solar absorptance of the upper surface of a roof must be not more than 0.45.

Roof lights must have—

1. a total area of not more than 5% of the floor area of the room or space served; and
2. transparent and translucent elements, including any imperforate ceiling diffuser, with a combined performance of—
   1. for Total system SHGC, in accordance with Table J4D5; and
   2. for Total system U-Value, not more than U3.9.

(1) The Total System U-Value of wall-glazing construction, including wall-glazing construction which wholly or partly forms the envelope internally, must not be greater than—

1. 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
2. for a Class 3 or 9c building or a Class 9a ward area—
   1. in climate zones 1, 3, 4, 6 or 7, U1.1; or
   2. in climate zones 2 or 5, U2.0; or
   3. in climate zone 8, U0.9.

(2) The Total System U-Value of display glazing must not be greater than U5.8.

(3) The Total System U-Value of wall-glazing construction must be calculated in accordance with Specification 37.

(4) Wall components of a wall-glazing construction must achieve a minimum Total R-Value of—

1. where the wall is less than 80% of the area of the wall-glazing construction, R1.0; or
2. where the wall is 80% or more of the area of the wall-glazing construction, the value specified in Table J4D6a.

(5) The solar admittance of externally facing wall-glazing construction, excluding wall-glazing construction which is wholly internal, must not be greater than—

1. 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
2. for a Class 3 or 9c building or a Class 9a ward area, the values specified in Table J4D6c.

(6) The solar admittance of a wall-glazing construction must be calculated in accordance with Specification 37.

(7) The Total system SHGC of display glazing must not be greater than 0.81 divided by the applicable shading factor specified in S37C7.

(1) A floor must achieve the Total R-Value specified in Table J4D7.

(2) For the purposes of (1), a slab-on-ground that does not have an in-slab heating or cooling system is considered to achieve a Total R-Value of R2.0, except—

1. in climate zone 8; or
2. 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.

(3) A floor must be insulated around the vertical edge of its perimeter with insulation having an R-Value greater than or equal to 1.0 when the floor—

1. is a concrete slab-on-ground in climate zone 8; or
2. has an in-slab or in-screed heating or cooling system, except where used solely in a bathroom, amenity area or the like.

(4) Insulation required by (3) for a concrete slab-on-ground must—

1. be water resistant; and
2. be continuous from the adjacent finished ground level—
   1. to a depth not less than 300 mm; or
   2. for the full depth of the vertical edge of the concrete slab-on-ground.