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10.7

NT Part 10.7 Sound insulation

NT Part 10.7 Sound insulation

NT 10.7.1 Sound insulation requirements2019: NT 3.8.6.2

(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 NT 10.7.1; and
  2. be installed in accordance with the appropriate requirements of NT 10.7.2 and NT 10.7.3.

(2) For the purposes of this Part, the RW may be determined in accordance with AS/NZS ISO 717.1.

Explanatory information

The wall configurations shown in Figures NT 10.7.1b, 10.7.1c, 10.7.1d, 10.7.1e, 10.7.1f, 10.7.1g, 10.7.1h, 10.7.1i, 10.7.1j, 10.7.1k, 10.7.1l, 10.7.1m, 10.7.1n, 10.7.1o, 10.7.1p, 10.7.1q, 10.7.1r, 10.7.1s and 10.7.1t are typical examples. Other proprietary methods are available for meeting the RW and sound impact levels required by NT 10.7.1.

Table 10.7.1 Required RW and sound impact levels for separating walls
Separating wall — location and penetrations Impact sound resistance (as per Figures NT 10.7.1b to 10.7.1h) RW (as per Figures NT 10.7.1i to 10.7.1u)
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 NT 10.7.1a) Yes 50
Type B: in all other cases to those listed as Type A (see Figure NT 10.7.1a) No 45
A soil and waste pipe or other penetration that serves or passes through a separating wall between houses — if the adjacent room is a habitable room (other than a kitchen) No 45
A soil and waste pipe or other penetration that serves or passes through a separating wall — if the room is a kitchen or any other room No 30
Insert NT figure (10.7.1a) 10.7.1 as follows:
NT Figure 10.7.1a: Required RW — plan view
image-10-7-1a-required-rw-plan-view-NT.svg
Insert NT figure (10.7.1b) 10.7.1 as follows:
NT Figure 10.7.1b: Construction of walls to reduce impact sound and achieve a 50 RW: cavity brickwork
image-10-7-1b-construction-of-walls-50-rw-cavity-brickwork-NT.svg
Figure Notes

2 leaves of 90 mm brick masonry with—

  1. all joints filled solid with mortar; and
  2. an air space not less than 40 mm between the leaves; and
  3. the leaves connected by ties in accordance with AS 3700, except ‘(for piers—isolated and engaged)’ is removed from Clause 8.5.1(d) and where Clause 8.5.1 requires design 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
  4. wall tie spacing as set out in Part 5.6.
Insert NT figure (10.7.1c) 10.7.1 as follows:
NT Figure 10.7.1c: Construction of walls to reduce impact sound and achieve a 50 RW: single leaf brickwork
image-10-7-1c-construction-of-walls-50-rw-single-leaf-brickwork-NT.svg
Figure Notes

80 mm thick brick masonry with—

  1. each face rendered 13 mm thick; and
  2. 50 mm x 12 mm thick timber battens at not more than 610 mm centres fixed to each face but not recessed into the render; and
  3. one layer of 12 mm thick softboard nailed to the battens; and
  4. 6 mm thick medium density hardboard adhesive-fixed into the softboard.
Insert NT figure (10.7.1d) 10.7.1 as follows:
NT Figure 10.7.1d: Construction of walls to reduce impact sound and achieve a 50 RW: concrete blockwork
image-10-7-1d-construction-of-walls-50-rw-concrete-blockwork-NT.svg
Figure Notes

190 mm thick concrete block masonry with—

  1. each face of the blocks fitted with 50 mm x 50 mm timber battens, spaced at not more than 610 mm centres, screw-fixed into resilient plugs with rubber inserts; and
  2. the space between the battens completely filled with mineral or glass wool blanket or batts not less than 50 mm thick; and
  3. the outer face of the battens finished with plasterboard not less than 10 mm thick.
Insert NT figure (10.7.1e) 10.7.1 as follows:
NT Figure 10.7.1e: Construction of walls to reduce impact sound and achieve a 50 RW: timber-framed walling (method 1)
image-10-7-1e-construction-of-walls-50-rw-timber-framed-walling-1-NT.svg
Figure Notes

70 mm x 45 mm F5 staggered timber studs at 600 mm centres both side on 120 mm x 35 mm F5 timber plates with—

  1. one layer of 16 mm fire-protective grade plasterboard on both faces; and
  2. 50 mm glass fibre batts.
Insert NT figure (10.7.1f) 10.7.1 as follows:
NT Figure 10.7.1f: Construction of walls to reduce impact sound and achieve a 50 RW: timber-framed walling (method 2)
image-10-7-1f-construction-of-walls-50-rw-timber-framed-walling-2-NT.svg
Figure Notes

70 mm x 45 mm F5 timber double studs at 450 mm - 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.

Insert NT figure (10.7.1g) 10.7.1 as follows:
NT Figure 10.7.1g: Construction of walls to reduce impact sound and achieve a 50 RW: steel stud walling (method 1)
image-10-7-1g-construction-of-walls-50-rw-steel-stud-walling-1-NT.svg
Figure Notes

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

  1. two layers of 13 mm fire-protective grade plasterboard to each side; and
  2. 50 mm glass wool cavity batts.
Insert NT figure (10.7.1h) 10.7.1 as follows:
NT Figure 10.7.1h: Construction of walls to reduce impact sound and achieve a 50 RW: steel stud walling (method 2)
image-10-7-1h-construction-of-walls-50-rw-steel-stud-walling-2-NT.svg
Figure Notes

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

  1. two layers of 13 mm fire-protective grade plasterboard to each side; and
  2. 50 mm glass wool cavity batts.
Insert NT figure (10.7.1i) 10.7.1 as follows:
NT Figure 10.7.1i: Clay brickwork to achieve RW of 45 (method 1)
image-10-7-1i-clay-brickwork-rw-45-1-NT.svg
Figure Notes

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

Insert NT figure (10.7.1j) 10.7.1 as follows:
NT Figure 10.7.1j: Clay brickwork to achieve RW of 45 (method 2)
image-10-7-1j-clay-brickwork-rw-45-2-NT.svg
Figure Notes

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.

Insert NT figure (10.7.1k) 10.7.1 as follows:
NT Figure 10.7.1k: Calcium silicate brickwork to achieve RW of 45 (method 1)
image-10-7-1k-calcium-silicate-brickwork-rw-45-1-NT.svg
Figure Notes

Calcium silicate brickwork 90 mm thick with one layer of 10 mm fire-protective grade plasterboard on each side.

Insert NT figure (10.7.1l) 10.7.1 as follows:
NT Figure 10.7.1l: Calcium silicate brickwork to achieve RW of 45 (method 2)
image-10-7-1l-calcium-silicate-brickwork-rw-45-2-NT.svg
Figure Notes

Calcium silicate brickwork 90 mm thick with one layer of 10 mm fire-protective grade plasterboard on metal furring channels.

Insert NT figure (10.7.1m) 10.7.1 as follows:
NT Figure 10.7.1m: Concrete blockwork to achieve RW of 45 (method 1)
image-10-7-1m-concrete-blockwork-rw-45-1-NT.svg
Figure Notes

Concrete blockwork with—

  1. 190 mm solid units (or thicker); and
  2. material density 2200 kg/m3.
Insert NT figure (10.7.1n) 10.7.1 as follows:
NT Figure 10.7.1n: Concrete blockwork to achieve RW of 45 (method 2)
image-10-7-1n-concrete-blockwork-rw-45-2-NT.svg
Figure Notes

Concrete blockwork with—

  1. 110 mm solid units (or thicker); and
  2. material density 2200 kg/m3; and
  3. material thickness — 83 mm minimum; and
  4. 10 mm plasterboard or 12 mm render on each face.
Insert NT figure (10.7.1o) 10.7.1 as follows:
NT Figure 10.7.1o: Concrete wall to achieve RW of 45
image-10-7-1o-concrete-wall-rw-45-NT.svg
Figure Notes

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

Insert NT figure (10.7.1p) 10.7.1 as follows:
NT Figure 10.7.1p: Steel stud walling to achieve RW of 45
image-10-7-1p-steel-stud-walling-rw-45-NT.svg
Figure Notes

Steel stud walling with—

  1. 2 layers of 16 mm thick fire-protective grade plasterboard fixed to each face; or
  2. 2 layers of 13 mm thick plasterboard on both sides of 75 mm studs.
Insert NT figure (10.7.1q) 10.7.1 as follows:
NT Figure 10.7.1q: Timber stud walling to achieve RW of 49
image-10-7-1q-timber-stud-walling-rw-49-NT.svg
Figure Notes

70 mmx 45 mm timber studs at 450 mm - 600 mm centres with—

  1. one layer of 16 mm fire-protective grade plasterboard on one face; and
  2. 50 mm glass fibre batts; and
  3. one layer of 16 mm fire-protective grade plasterboard on metal resilient channel.
Insert NT figure (10.7.1r) 10.7.1 as follows:
NT Figure 10.7.1r: Timber stud walling to achieve RW of 46
image-10-7-1r-timber-stud-walliing-rw-46-NT.svg
Figure Notes

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

Insert NT figure (10.7.1s) 10.7.1 as follows:
NT Figure 10.7.1s: Ducts or other construction separating soil and waste pipes from units — masonry to achieve RW of 30
image-10-7-1s-ducts-or-other-construction-masonry-rw-30-NT.svg
Figure Notes

Masonry not less than 90 mm thick.

Insert NT figure (10.7.1t) 10.7.1 as follows:
NT Figure 10.7.1t: Ducts or other construction separating soil and waste pipes from units — plasterboard to achieve RW of 30 (method 1)
image-10-7-1t-ducts-or-other-construction-plasterboard-rw-30-1-NT.svg
Figure Notes

2 layers of plasterboard each 10 mm thick, fixed to timber studs not less than 75 mm x 50 mm and spaced at not more than 400 mm centres.

Insert NT figure (10.7.1u) 10.7.1 as follows:
NT Figure 10.7.1u: Ducts or other construction separating soil and waste pipes from units — plasterboard to achieve RW of 30 (method 2)
image-10-7-1u-ducts-or-other-construction-plasterboard-rw-30-2-NT.svg
Figure Notes

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.

NT 10.7.2 General installation requirements for walls2019: NT 3.8.6.3

(1) To achieve an appropriate RW and impact sound resistance, walls must—

  1. be installed in accordance with the appropriate requirements contained in (2) to (6); and
  2. at the junction of sound insulated walls with perimeter walls and roof cladding, be sealed in accordance with any details in Figure NT 10.7.2a.

(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 and any adjoining construction must be filed 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 (a) 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 (see Figure NT 10.7.2b).
  3. Joints between sheets or between sheets and any adjoining construction must be taped and filled solid.
  4. Fire-protective grade plasterboard (where nominated) must be the grade manufactured for use in fire-resisting construction.

(5) Steel studs and perimeter members must be installed as follows:

  1. The section of steel must be not less than 0.6 mm thick.
  2. Studs must be not less than 63 mm in depth unless another depth is specified in NT 10.7.1.
  3. Studs must be fixed to steel top and bottom plates of sufficient depth to permit secure fixing of the plasterboard.
  4. All steel members at the perimeter of the wall must be securely fixed to the adjoining structure and be bedded in resilient compound or the joints must be caulked so that there are no voids between the steel members and the wall.

(6) Timber studs and permitter 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 that there are no voids between the timber members and the wall.
Insert NT figure (10.7.2a) 10.7.2 as follows:
NT Figure 10.7.2a: Sound insulation between units — double stud wall configuration
image-10-7-2a-sound-insulation-between-units-double-stud-wall-configuration-NT.svg
Insert NT figure (10.7.2b) 10.7.2 as follows:
NT Figure 10.7.2b: Typical installation of plaster sheets for sound insulation
image-10-7-2b-typical-installation-of-plaster-sheets-for-sound-insulation-NT.svg

NT 10.7.3 Soil and waste pipes2019: NT 3.8.6.4

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.