NCC 2019 Volume Two
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Part 3.8.6 Sound insulation

Part 3.8.6 Sound insulation

Appropriate Performance Requirements

Appropriate Performance Requirements

Where an alternative sound insulation system is proposed as a Performance Solution to that described in Part 3.8.6, that proposal must comply with—

  1. Performance RequirementP2.4.6; and
  2. the relevant Performance Requirements determined in accordance with A2.2(3) and A2.4(3) as applicable.

3.8.6.1 Application

Compliance with this acceptable construction practice satisfies Performance Requirement P2.4.6 for sound insulation.

3.8.6.2 Sound insulation requirements

(a)

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—

(i)

have an Rw + Ctr (airborne) not less than 50; and

(ii)

be of discontinuous construction if it separates a bathroom, sanitary compartment, laundry or kitchen in one Class 1 building from a habitable room (other than a kitchen) in an adjoining Class 1 building (see Figure 3.8.6.1).

(b)

For the purposes of (a)(ii), discontinuous construction means a wall system that has two separate leaves and that is not a staggered stud wall, that complies with the following:

(i)

The wall has a minimum 20 mm cavity between leaves.

(ii)

For masonry walls, where wall ties are required to connect leaves, the ties are of the resilient type.

(iii)

For walls other than masonry, there is no mechanical linkage between leaves except at the periphery.

(c)

A wall required to have sound insulation must continue to—

(i)

the underside of the roof above; or

(ii)

a ceiling that provides the sound insulation required for the wall.

Explanatory information:

Explanatory information:

Insulation to reduce both airborne and impact noise transmission is required for parts of a wall that are common to adjoining Class 1 buildings but not parts of a wall located in the subfloor.

3.8.6.3 Determination of airborne sound insulation ratings

(a)

The Rw + Ctr sound insulation rating required by 3.8.6.2(a)(i) must—

(i)

be determined in accordance with AS/NZS ISO 717.1, using results from laboratory measurements; or

(ii)

comply with Table 3.8.6.1a to Table 3.8.6.1d and the relevant provisions of 3.8.6.4.

Explanatory information:

Explanatory information:

Rw is a measure of airborne sound insulation. Ctr is a spectrum adjustment factor that adjusts for low frequency sound levels. Ctr has been chosen in recognition of the problems caused by the high bass frequency outputs of modern home theatre systems and music reproduction equipment used by occupants of Class 1 buildings.

The wall configurations shown in Table 3.8.6.1a to Table 3.8.6.1d are typical examples. Other proprietary methods are available via testing to AS/NZS ISO 717.1 for meeting the Rw + Ctr requirements of 3.8.6.2.

Figure 3.8.6.1 Required airborne and impact sound insulation — Plan view
v2_Fig3861_2019.svg

3.8.6.4 Construction of sound insulated walls

To achieve the appropriate level of sound insulation, walls must be constructed as follows:

(a)

Stud wall junction — junctions of sound insulated walls with any perimeter walls and roof cladding must be sealed in accordance with Figure 3.8.6.2.

Figure 3.8.6.2 Sound insulation between buildings - Stud wall junctions
v2_Fig3862_2019.svg
(b)

Masonry — units must be laid with all joints filled solid, except for articulation joints complying with 3.3.5.13, including those between the masonry and any adjoining construction.

(c)

Concrete panels — must have joints between panels and any adjoining construction filled solid.

(d)

Plasterboard sheeting —

(i)

If two layers are required, the second layer joints must not coincide with those of the first layer (see Figure 3.8.6.3).

(ii)

Joints between sheets including the outer layer or between sheets and any adjoining construction must be taped and filled solid.

Figure 3.8.6.3 Typical installation of plaster sheets for sound insulation
v2_Fig3863_2009.svg
(e)

Steel framed construction — steel framing and perimeter members must be installed as follows:

(i)

Steel framing members must be not less than 0.6 mm thick.

(ii)

Studs must be not less than 63 mm in depth unless another depth is specified in Table 3.8.6.1a to Table 3.8.6.1d.

(iii)

All steel members at the perimeter of the wall must be securely fixed to the adjoining structure and the joints must be caulked so that there are no voids between the steel members and the wall.

(f)

Timber-framed construction — timber studs and perimeter members must be installed as follows:

(i)

Noggings and like members must not bridge between studs supporting different wall leaves.

(ii)

All timber members at the perimeter of the wall must be securely fixed to the adjoining structure and the joints must be caulked so there are no voids between the timber members and the wall.

3.8.6.5 Services

(a)

Services must not be chased into concrete or masonry separating walls.

(b)

If a duct, soil, waste, water supply or storm water pipe is located in a separating wall—

(i)

a door or panel providing access to a duct or pipe required to be separated must—

(A)

not open into any habitable room, other than a kitchen; and

(B)

in any other part must be firmly fixed so as to overlap the frame or rebate of the frame by not less than 10 mm and be constructed of—

(aa)

wood, plasterboard or blockboard not less than 33 mm thick; or

(bb)

compressed fibre reinforced cement sheeting not less than 9 mm thick; or

(cc)

other suitable material with a mass per unit area not less than 24.4 kg/m2; and

(ii)

in the case of a water supply pipe, it must—

(A)

only be installed in discontinuous construction; and

(B)

in the case of a water supply pipe that serves one dwelling, not be fixed to the wall leaf on the side of any other dwelling and have a clearance not less than 10 mm to the other wall leaf.

(c)

Electrical outlets must be offset from each other—

(i)

in masonry walling, not less than 100 mm; and

(ii)

in timber or steel-framed walling, not less than 300 mm.

Table 3.8.6.1a Acceptable forms of construction for masonry walls

Description

Rw + Ctr (not less than)

Construction

Two leaves of 110 mm clay brick masonry with—

  1. cavity not less than 50 mm between leaves; and
  2. 50 mm thick glass wool insulation with a density of 11 kg/m3 or 50 mm thick polyester insulation with a density of 20 kg/m3 in the cavity.

50
v2_Tab386201_2005.svg

Two leaves of 110 mm clay brick masonry with—

  1. cavity not less than 50 mm between leaves; and
  2. 13 mm cement render on each outside face.

50
v2_Tab386202_2005.svg

Single leaf of 110 mm clay brick masonry with—

  1. a row of 70 mm x 35 mm timber studs or 64 mm steel studs at 600 mm centres, spaced 20 mm from the masonry wall; and
  2. 50 mm thick mineral insulation or glass wool insulation with a density of 11 kg/m3 positioned between studs; and
  3. one layer of 13 mm plasterboard fixed to outside face of studs and outside face of masonry.

50
v2_Tab386203_2005.svg

Single leaf of 90 mm clay brick masonry with—

  1. a row of 70 mm x 35 mm timber studs or 64 mm steels studs at 600 mm centres, spaced 20 mm from each face of the masonry wall; and
  2. 50 mm thick mineral insulation or glass wool insulation with a density of 11 kg/m3 positioned between studs in each row; and
  3. one layer of 13 mm plasterboard fixed to studs on each outside face.

50
v2_Tab386204_2005.svg

Single leaf of 220 mm brick masonry with 13 mm cement render on each face.

50
v2_Tab386205_2005.svg
Table 3.8.6.1b Acceptable forms of construction for concrete walls

Description

Rw+Ctr (not less than)

Construction

150 mm thick plain off form concrete.

50
v2_Tab386206_2005.svg

200 mm thick concrete panel with one layer of 13 mm plasterboard or 13 mm cement render on each face.

50
v2_Tab386207_2005.svg

100 mm thick concrete panel with—

  1. a row of 64 mm steel studs at 600 mm centres, spaced 25 mm from the concrete panel; and
  2. 80 mm thick polyester insulation or 50 mm thick glass wool insulation with a density of 11 kg/m3, positioned between studs; and
  3. two layers of 13 mm plasterboard fixed to outside face of studs and one layer of 13 mm plasterboard fixed to outside face of concrete panel.

50
v2_Tab386208_2005.svg

125 mm thick concrete panel with—

  1. a row of 64 mm steel studs at 600 mm centres, spaced 20 mm from the concrete panel; and
  2. 70 mm polyester insulation with a density of 9 kg/m3, positioned between studs; and
  3. one layer of 13 mm plasterboard fixed to the outside face of the studs.

50
v2_Tab386209_2005.svg
Table 3.8.6.1c Acceptable forms of construction for autoclaved aerated concrete walls

Description

Rw+Ctr (not less than)

Construction

75 mm thick autoclaved aerated concrete wall panel with—

  1. a row of 64 mm steel studs at 600 mm centres, spaced 20 mm from the autoclaved aerated concrete wall panel; and
  2. 75 mm thick glass wool insulation with a density of 11 kg/m3 positioned between studs; and
  3. one layer of 10 mm moisture resistant plasterboard or 13 mm fire protective grade plasterboard fixed to outside face of studs and outside face of autoclaved aerated concrete wall panel.

50
v2_Tab386210_2005.svg

75 mm thick autoclaved aerated concrete wall panel with—

  1. a row of 64 mm steel studs at 600 mm centres, spaced 35 mm from the autoclaved aerated concrete panel wall; and
  2. 28 mm metal furring channels fixed to the outside face of the autoclaved aerated concrete wall panel, with 50 mm thick polyester insulation with a density of 9 kg/m3 positioned between furring channels and one layer of 13 mm fire protective grade plasterboard fixed to furring channels; and
  3. 105 mm thick glass wool insulation with a density of 7 kg/m3 positioned between studs; and
  4. one layer of 13 mm fire protective grade plasterboard fixed to the outside face of the studs.

50
v2_Tab386211_2005.svg

Two leaves of 75 mm autoclaved aerated concrete wall panel with—

  1. a cavity not less than 30 mm between panels containing 50 mm glass wool insulation with a density of 11 kg/m3; and
  2. one layer of 10 mm plasterboard fixed to outside face of each panel.

50
v2_Tab386212_2005.svg
Table 3.8.6.1d Acceptable forms of construction for timber and steel framed walls

Description

Rw+Ctr (not less than)

Construction

Two rows of 90 x 35 mm timber studs or two rows of 64 mm steels studs at 600 mm centres with—

  1. an air gap not less than 20 mm between the rows of studs; and
  2. 50 mm thick glass wool insulation or 60 mm thick polyester insulation with a density of 11 kg/m³; positioned between one row of studs, and
  3. two layers of 13 mm fire protective grade plasterboard or one layer of 6 mm fibre cement sheet and one layer of 13 mm fire protective grade plasterboard, fixed to outside face of studs.

50
v2_Tab386213_2005.svg

Two rows of 64 mm steel studs at 600 mm centres with—

  1. an air gap not less than 80 mm between the rows of studs; and
  2. 200 mm thick polyester insulation with a density of 14 kg/m3; positioned between studs; and
  3. one layer of 13 mm fire-protective grade plasterboard and one layer 13 mm plasterboard on one outside face and one layer of 13 mm fire-protective grade plasterboard on the other outside face.

50
v2_Tab386214_2005.svg

State and Territory Variations

State and Territory Variations

In Northern Territory Part 3.8.6 acceptable construction practice is replaced with the following:

Acceptable construction practice

3.8.6.1 Application

Compliance with this Part satisfies Performance Requirement P2.4.6 for sound insulation.

3.8.6.2 Sound insulation requirements

  1. A separating wall between two or more Class 1 buildings must—
    1. achieve the weighted sound reduction index (Rw) and impact sound resistance required by Table 3.8.6.1; and
    2. be installed in accordance with the appropriate requirements of 3.8.6.3 and 3.8.6.4; and
  2. for the purpose of this Part, the Rw may be determined in accordance with AS/NZS ISO 717.1.
Table 3.8.6.1 Required R w and sound impact levels for separating walls

Separating wall — location and penetrations

Impact sound resistance (as per Table 3.8.6.2 )

R w (as per Table 3.8.6.3)

Type A

Between a bathroom, sanitary compartment, laundry or kitchen and a habitable room (other than a kitchen) in an adjoining Class 1 building (dwelling) (see Figure 3.8.6.1).

Yes

50

Type B

In all other cases to those listed as Type A. (See Figure 3.8.6.1)

No

45

Soil and waste pipes

A waste pipe or other penetration that serves or passes through a separating wall between houses—

  1. If the adjacent room is a habitable room (other than a kitchen); or

No

45

Soil and waste pipes

A waste pipe or other penetration that serves or passes through a separating wall between houses—

  1. If the room is a kitchen or any other room.

No

30

Figure 3.8.6.1 Required R w —Plan view

v2_Fig3861sv_2005.svg

3.8.6.3 General installation requirements for walls

  1. To achieve the appropriate Rw and impact sound resistance, walls must—
    1. be installed in accordance with the appropriate requirements contained in (b) to (f); and
    2. at the junction of sound insulated walls with perimeter walls and roof cladding, be sealed in accordance with any relevant detail in Figure 3.8.6.3.
  2. Masonry units must—
    1. be laid with all joints filled solid, including those between the masonry and any adjoining construction; and
    2. not be chased for services.
  3. Joints between concrete slabs, wall units and any adjoining construction must be filled solid.
  4. Plasterboard must be installed as follows:
    1. If one layer is required under this Part, joints must be staggered with the joints in sheets on the opposite face of the wall.
    2. If 2 layers are required, the first layer must be fixed according to (i) and the second layer must be fixed to the first layer with nails, screws or adhesive so that the joints do not coincide with those of the first layer.
    3. Joints between sheets or between sheets and any adjoining construction must be taped and filled solid.
    4. Fire-protective grade plasterboard (when nominated) must be the grade manufactured for use in fire-resisting construction.

Figure 3.8.6.2 Typical installation of plaster sheets for sound insulation

v2_Fig3862sv_2005.svg
  1. Steel studs and perimeter members must be installed as follows:
    1. The section of steel must be not less than 0.6 mm thick.
    1. Studs must be not less than 63 mm in depth unless another depth is specified in the Table.
    1. Studs must be fixed to steel top and bottom plates of sufficient depth to permit secure fixing of the plasterboard.
    1. All steel members at the perimeter of the wall must be securely fixed to the adjoining structure and bedded in resilient compound or the joints must be caulked so that there are no voids between the steel members and the wall.
  2. Timber studs and perimeter members must be installed as follows:
    1. Studs must be fixed to top and bottom plates of sufficient depth to permit secure fixing of the plasterboard.
    2. Noggings and like members must not bridge between studs supporting different wall leaves.
    3. All timber members at the perimeter of the wall must be securely fixed to the adjoining structure and bedded in resilient compound or the joints must be caulked so there are no voids between the timber members and the wall.

      3.8.6.4Soil and waste pipes

      If a soil or waste pipe passes through a separating wall—

  1. a door or panel providing access to the pipe must not open into any habitable room, other than a kitchen; and
  2. an access door or panel in any other part must be firmly fixed so as to overlap the frame or rebate of the frame by not less than 10 mm, be fitted with a sealing gasket along all edges and constructed of—
    1. wood, plasterboard or blockboard not less than 38 mm thick; or
    2. compressed fibre reinforced cement sheeting not less than 9 mm thick; or
    3. other suitable material with a mass per unit area not less than 24.4 kg/m2.

      Explanatory information:

      Explanatory information:

      The wall configurations shown in Tables 3.8.6.2 and 3.8.6.3 are typical examples. Other proprietary methods are available for meeting the Rw and sound impact levels required by Table 3.8.6.1.

Table 3.8.6.2 Construction of walls to reduce impact sound and achieve a 50 R w

Wall construction type

Design diagram — Plan view

Cavity brickwork

v2_Tab3862asv_2005.svg

2 leaves 90 mm brick masonry with—

(a) all joints filled solid with mortar; and

(b) an air space not less than 40 mm between the leaves; and

(c) the leaves connected only by ties in accordance with AS& 3700, except '(for piers—isolated or engaged)' is removed from Clause 8.5.1(d) and where Clause 8.5.1 requires design as for unreinforced masonry in accordance with Section 7, the member must also be designed as unreinforced masonry in accordance with Tables 10.3 and 4.1(a)(i)(C) of AS 3700; and

(d) wall tie spacing in accordance with details set out in Part 3.3.

Single leaf brickwork

v2_Tab3862bsv_2005.svg

80 mm thick brick masonry with—

(a) each face rendered 13 mm thick; and

(b) 50x12 mm thick timber battens at not more than 610 mm centres fixed to each face but not recessed into the render; and

(c) one layer of 12 mm thick softboard nailed to the battens; and

(d) 6 mm thick medium density hardboard adhesive-fixed to the softboard.

Concrete blockwork

v2_Tab3862csv_2005.svg

190 mm thick concrete block masonry with—

(a) each face of the blocks fitted with 50x50 mm timber battens, spaced at not more than 610 mm centres, screw-fixed into resilient plugs with rubber inserts; and

(b) the space between the battens completely filled with mineral or glass wool blanket or batts not less than 50 mm thick; and

(c) the outer face of the battens finished with plasterboard not less than 10 mm thick.

Timber-framed walling

v2_Tab3862dsv_2005.svg

70 x 45 mm F5 staggered timber studs at 600 mm centres both sides on 120x35 mm F5 timber plates with—

(a) one layer of 16 mm fire protective grade plasterboard on both faces; and

(b) 50 mm glass fibre batts.

Timber-framed walling

v2_Tab3862esv_2005.svg

70 x 45 mm F5 timber double studs at 450 – 600 mm centres with an air space not less than 20 mm between studs with two layers of 13 mm fire protective grade plasterboard on both faces.

Steel stud walling

v2_Tab3862fsv_2005.svg

64 mm staggered metal studs (0.75 mm base metal thickness) at 600 mm centres both sides, clipped in 92 mm metal tracks with—

(a) two layers of 13 mm fire protective grade plasterboard to each side; and

(b) 50 mm glasswool cavity batts.

Steel stud walling

v2_Tab3862gsv_2005.svg

64 mm double metal studs (0.75 mm base metal thickness) at 600 mm centres with an air space not less than 20 mm between studs, in separate frames with no mechanical links with—

(a) two layers of 13 mm fire protective grade plasterboard to each side; and

(b) 50 mm glasswool cavity batts.
Table 3.8.6.3 R w applicable to construction

Wall construction type

R w

Design diagram — Plan view

Clay brickwork

110 mm thick in one or more leaves and with a mass per unit area of not less than 290 kg/m2.

45

v2_Tab3863asv_2005.svg

Clay brickwork

80 mm thick, pressed brick and rendered 13 mm on one side, the mass per unit area of the unrendered wall being not less than 215 kg/m2.

45

v2_Tab3863bsv_2005.svg

Calcium silicate brickwork

90 mm thick calcium silicate brick with one layer of 10 mm fire protective grade plasterboard on each side.

45

v2_Tab3863csv_2005.svg

Calcium silicate brickwork

90 mm thick calcium silicate brick with one layer of 10 mm fire protective plasterboard and one layer of fire protective plasterboard on metal furring channels.

45

v2_Tab3863dsv_2005.svg

Concrete blockwork

190 mm solid units (or thicker)

Material density 2200 kg/m3

45

v2_Tab3863esv_2005.svg

Concrete blockwork

110 mm solid units (or thicker)

Material density 2200 kg/m3

Material thickness — 83 mm min.

10 mm plasterboard or 12 mm render on each face.

45

v2_Tab3863fsv_2005.svg

Concrete wall

In-situ concrete — 125 mm thick and with a density of not less than 2200 kg/m3.

45

v2_Tab3863gsv_2005.svg

Steel stud walling

With 2 layers of 16 mm thick fire-protective grade plasterboard fixed to each face.

45

v2_Tab3863hsv_2005.svg

Steel stud walling

With 2 layers of 13 mm plasterboard on both sides of 75 mm studs.

45

v2_Tab3863isv_2005.svg

Timber stud walling

70 x 45 mm timber studs at 450 – 600 mm centres with

49

v2_Tab3863jsv_2005.svg

(a) one layer of 16 mm fire protective grade plasterboard on one face; and

(b) 50 mm glass fibre batts; and

(c) one layer of 16 mm fire protective grade plasterboard on metal resilient channel.

Timber stud walling

70 x 45 mm timber studs at 450 – 600 mm centres with two layers of 16 mm fire protective grade plasterboard on both sides.

46

v2_Tab3863ksv_2005.svg

Ducts or other construction separating soil and waste pipes from units — masonry

Not less than 90 mm thick.

30

v2_Tab3863lsv_2005.svg

Ducts or other construction separating soil and waste pipes from units — plasterboard

2 layers of plasterboard each 10 mm thick, fixed to timber studs not less than 75x50 mm and spaced at not more than 400 mm centres.

30

v2_Tab3863msv_2005.svg

Ducts or other construction separating soil and waste pipes from units — plasterboard

2 layers of plasterboard each 13 mm thick, one on each side of steel studs not less than 50 mm deep and spaced at not more than 400 mm centres.

30

v2_Tab3863nsv_2005.svg

Figure 3.8.6.3

Sound insulation between units — Double stud wall configuration

v2_Fig3863sv_2009.svg