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9.3

Part 9.3 Fire protection of separating walls and floors

Part 9.3 Fire protection of separating walls and floors

(1) A separating wall between Class 1 buildings, or a wall that separates a Class 1 building from a Class 10a building which is not associated with the Class 1 building must—

  1. be constructed—
    1. having an FRL of not less than 60/60/60; or
    2. of masonry not less than 90 mm thick; and
  2. commence at the footings or ground slab (see Figure 9.3.1a), except for horizontal projections to which 9.3.4 applies (see Figure 9.3.4); and
  3. extend—
    1. if the building has a non-combustible roof covering, to the underside of the roof covering (see Figure 9.3.1a and Figure 9.3.1b); or
    2. if the building has a combustible roof covering, to not less than 450 mm above the roof covering (see Figure 9.3.1a); and
  4. comply with (2) to (5) and 9.3.2 as applicable.

(2) A separating wall of lightweight construction must be tested in accordance with Specification 6.

(3) A separating wall complying with (1)(c)(i)—

  1. must not be crossed by timber or other combustible building elements except for roof battens with dimensions of 75 x 50 mm or less, or roof sarking; and
  2. must have any gap between the top of the wall and the underside of the roof covering packed with mineral fibre or other suitable fire-resisting material.

(4) Where a building has a masonry veneer external wall, any gap between the separating wall and the external masonry veneer must be—

  1. not more than 50 mm; and
  2. packed with a mineral fibre or other suitable fire-resisting material with the packing arranged to maintain any weatherproofing requirements of H2D4.

(5) Eaves, verandahs and similar spaces that are open to the roof space and are common to more than one Class 1 dwelling must be separated by a non-combustible vertical lining (see Figure 9.3.1c).

Figure 9.3.1a Separating wall construction
image-9-3-1a-separating-wall-construction.svg
Figure 9.3.1b Separating wall construction — Underside of non-combustible roof cladding (diagram 1)
image-9-3-1b-separating-wall-construction-underside-of-non-combustible-roof-cladding-diagram-1.svg
Figure 9.3.1c Separating wall construction — Underside of non-combustible roof cladding (diagram 2)
image-9-3-1c-separating-wall-construction-underside-of-non-combustible-roof-cladding-diagram-2.svg
Figure Notes

Elements crossing the non-combustible vertical lining must comply with 9.3.1(3).

(1) Any service opening, other than those listed in (2), (3) and (4), in a separating wall must have construction with an FRL of not less than -/60/60.

(2) If an electrical wire or cable penetrates a separating wall—

  1. the service and building element at the penetration must—
    1. be identical with a prototype assembly that has been tested in accordance with AS 4072.1 and AS 1530.4 and achieve an FRL of not less than -/60/60; or
    2. differ from a prototype assembly of the service and building element in accordance with AS 4072.1; or
  2. the service must be installed so that—
    1. the opening is neatly formed, cut or drilled and no closer than 50 mm to any other service; and
    2. the opening is no larger in cross-section than—
      1. 2000 mm2 if only a single cable is accommodated and the gap between the cable and the wall is no wider than 15 mm; or
      2. 500 mm2 in any other case; and
    3. any gap between the service and the wall is packed with mineral fibre or other suitable fire-resisting material.

(3) If an electrical switch, outlet, socket or the like is accommodated in a separating wall—

  1. the service and building element at the penetration must—
    1. be identical with a prototype assembly which has been tested in accordance with AS 4072.1 and AS 1530.4 and achieve an FRL of not less than -/60/60; or
    2. differ from a prototype assembly of the service and building element in accordance with AS 4072.1; or
  2. the service must be installed so that—
    1. the opening or recess—
      1. is not located opposite any point within 300 mm horizontally or 600 mm vertically of any opening or recess on the opposite side of the wall; or
      2. does not extend beyond half the thickness of the wall; and
    2. any gap between the service and the wall is packed with mineral fibre or other suitable fire-resisting material.

(4) Other than where a tested system is used in accordance with (3)(a), if an electrical switch, socket, outlet or the like is accommodated in a hollow separating wall, the cavity immediately behind the service must be framed and packed with mineral fibre or other suitable fire-resisting material (see Figure 9.3.2).

Figure 9.3.2 Separating wall construction — Services in cavity construction
image-9-3-2-separating-wall-construction-services-in-cavity-construction.svg

Explanatory information

For the purposes of 9.3.2 and 10.7.2, a reference to a separating wall includes a wall that separates a Class 1 building from a Class 10a building that is not associated with the Class 1 building.

It is important that any opening in a separating wall between Class 1 buildings does not allow the free passage of fire between buildings. Many designs would require the installation of openings for electrical cables and outlets in these walls. 9.3.2 therefore allows such openings provided they comply with the requirements of that provision.

A reference to a hollow separating wall in 9.3.2(4) may include a stud wall, masonry cavity wall or a wall of hollow blockwork.

Part 10.7 (sound insulation) also contains requirements relevant to separating walls, in addition to the provisions of this Part. This includes installation requirements for walls and services to achieve appropriate levels of sound insulation.

Combustible roof lights, skylights or the like installed in a roof or part of a roof required to have a non-combustible covering must—

  1. have an aggregate area not more than 20% of the roof or part of the roof; and
  2. be not less than 900 mm from the vertical projection of a separating wall extending to the underside of the roof covering.

(1) Where a horizontal projection forms part of a separating wall complying with 9.3.1, any horizontal projection within 1.8 m on each side of the separating wall (see Figure 9.3.4) must—

  1. be a floor/ceiling or floor/soffit system incorporating a ceiling or soffit which has a resistance to the incipient spread of fire to the space above itself of not less than 60 minutes; or
  2. have an FRL not less than 30/30/30 when tested from the underside; or
  3. have a fire-protective covering on the underside of the floor, including beams incorporated in it, if the floor is combustible or of metal.

(2) The part of the separating wall that projects outwards horizontally must—

  1. extend to the underside of the floor/ceiling or floor/soffit system complying with (1); and
  2. not be crossed by timber or other combustible building elements except for framing members with dimensions of 75 x 50 mm or less, or sarking; and
  3. have any gap between the bottom of the wall and the underside of the floor/ceiling or floor/soffit system packed with mineral fibre or other suitable fire-resisting material.

(3) Where a floor subject to (1)(b) depends on direct vertical or lateral support from another part to maintain its FRL, that supporting part must have an FRL of not less than 30/-/-.

(4) Where a service passes through a floor referred to in (1), the penetration must not reduce the fire performance of the floor or covering.

Figure 9.3.4 Horizontal projection forming part of a separating wall
image-9-3-4-horizontal-projection-forming-part-of-a-separating-wall.svg
Figure Notes

Horizontal projections within 1.8 m of another building must be protected in accordance with 9.3.4(1).