NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings
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28

Specification 28 Sound insulation for building elements

Specification 28 Sound insulation for building elements

NCC Blurbs

This Specification lists the weighted sound reduction index RW for some common forms of construction.

NCC Title

Scope

NCC State
NT
NCC Variation Type
Replacement
NCC SPTC Current
Scope

This Specification lists the weighted sound reduction index RW for some common forms of construction.

NCC Blurbs

The forms of construction listed in NT S28C3 are considered to have the RW stated in that clause if installed as follows:

  1. Masonry: units must be laid with all joints filled solid, including those between the masonry and any adjoining construction.
  2. Concrete slabs: joints between concrete slabs and any adjoining construction must be filled solid.
  3. Plasterboard—
    1. if one layer is required under this Specification, it must be screw-fixed to the studs with joints staggered on opposite faces; and
    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; and
    3. joints between sheets or between sheets and any adjoining construction must be taped and filled solid; and
    4. fire-protective grade plasterboard must be the special grade manufactured for use in fire-resisting construction.
  4. Steel studs and perimeter members—
    1. the section of steel must be not less than 0.6 mm thick; and
    2. studs must be not less than 63 mm in depth unless another depth is listed in NT S28C3; and
    3. studs must be fixed to steel top and bottom plates of sufficient depth to permit secure fixing of the plasterboard; and
    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.
NCC Title

Construction deemed-to-satisfy

NCC State
NT
NCC Variation Type
Replacement
NCC SPTC Current
Construction deemed-to-satisfy

Wall systems listed in S28C4 to S28C7 having a minimum 20 mm cavity between 2 separate leaves are deemed to be discontinuous construction if—

  1. for masonry, where wall ties are required to connect leaves, the ties are of the resilient type; and
  2. for other than masonry, there is no mechanical linkage between leaves except at the periphery.
NCC Blurbs

(1) Construction in accordance with the following has an RW of not less than 45:

  1. Walls — clay brickwork:
    1. 230 mm thick in one or more leaves and with a mass per unit area of not less than 290 kg/m2.
    2. 110 mm thick rendered 13 mm thick on both sides with a mass per unit area of the unrendered wall being not less than 190 kg/m2.
    3. 110 mm thick, of semi-dry-pressed bricks and rendering 13 mm on one side, the mass per unit area being not less than 215 kg/m2.
    4. 110 mm thick, of extruded brick and rendered 13 mm on one side, the mass per unit area being not less than 180 kg/m2.
  2. Walls — concrete brickwork: 110 mm thick with a mass per unit area of not less than 195 kg/m2.
  3. Walls — concrete blockwork:
    1. 190 mm thick with a mass per unit area of not less than 215 kg/m2.
    2. 140 mm thick, the wall thickness of the blocks being not less than 44 mm and with—
      1. 50 mm x 50 mm timber battens spaced at not more than 610 mm centres screw-fixed on one face of the blocks into resilient plugs with rubber inserts between the battens and the wall; and
      2. the face of the battens clad with 13 mm thick standard plasterboard; and
      3. a mass per unit area of the whole system of not less than 220 kg/m2.
  4. Walls — concrete:
    1. In-situ concrete — 125 mm thick and with a density of not less than 2200 kg/m3.
    2. In-situ concrete — 100 mm thick and with a density of not less than 2500 kg/m3.
    3. Precast concrete — 100 mm thick and without joints.
  5. Walls — steel stud walling:
    1. With 2 layers of 16 mm thick fire-protective grade plasterboard fixed to each face.
    2. With—
      1. 1 layer of 13 mm thick fire-protective grade plasterboard fixed to one face, and before fixing, 50 mm thick mineral or glass wool blanket or batts stapled to the back of each sheet so that the sheet is completely covered; and
      2. 2 layers of 13 mm thick fire-protective grade plasterboard fixed to the other face.
    3. With—
      1. 1 layer of 16 mm thick fire-protective grade plasterboard fixed to one face; and
      2. 50 mm thick mineral or glass wool blanket or batts wedged firmly between the studs; and
      3. 2 layers of fire-protective grade plasterboard fixed to the other face, the inner layer being 16 mm thick and the outer layer being 13 mm.
    4. With 2 layers of 13 mm plasterboard on both sides of 75 mm studs.
  6. Floors — concrete:
    1. In-situ concrete slab — 125 mm thick and with a density of not less than 2200 kg/m3.
    2. In-situ concrete slab — 100 mm thick and with a density of not less than 2500 kg/m3.
    3. Pre-cast concrete slab — 100 mm thick and without joints.
  7. Floors — timber, comprising—
    1. timber joists not less than 175 mm x 50 mm; and
    2. 75 mm thick mineral or glass wool blanket or batts cut to fit tightly between joists and laid on 10 mm thick plasterboard fixed to underside of joists; and
    3. 25 mm thick mineral or glass wool blanket or batts laid over entire floor, including tops of joists before flooring is laid; and
    4. tongued and grooved boards not less than 19 mm thick, secured to 75 mm x 50 mm battens; and
    5. the assembled flooring laid over the joists, but not fixed to them, with the battens lying between the joists.

(2) Ducts or other construction separating soil and waste pipes from units, constructed in accordance with the following, have an RW of not less than 30:

  1. Masonry — not less than 90 mm thick.
  2. Plasterboard — 2 layers of plasterboard:
    1. 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.
    2. 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.
NCC Title

RW applicable to construction

NCC State
NT
NCC Variation Type
Replacement
NCC SPTC Current
RW applicable to construction

(1) The forms of wall construction described in S28C4 to S28C7 and floor construction described in S28C8 to S28C10, are considered to have the Rw, Rw + Ctr and Ln,w stated in those clauses.

(2) The forms of construction referred to in (1) must be installed as follows:

  1. Masonry units must be laid with all joints filled solid, including those between the masonry and any adjoining construction.
  2. Joints between concrete slabs or panels and any adjoining construction must be filled solid.
  3. For sheeting materials—
    1. if one layer is required on both sides of a wall, it must be fastened to the studs with joints staggered on opposite sides; and
    2. if two layers are required, the second layer must be fastened over the first layer so that the joints do not coincide with those of the first layer; and
    3. joints between sheets or between sheets and any adjoining construction must be taped and filled solid.
  4. Timber or steel-framed construction — perimeter framing members must be securely fixed to the adjoining structure and—
    1. bedded in resilient compound; or
    2. the joints must be caulked so that there are no voids between the framing members and the adjoining structure.
  5. Services must not be chased into concrete or masonry elements.
  6. A door or panel required to have a certain Rw + Ctr that provides access to a duct, pipe or other service must—
    1. not open into any habitable room (other than a kitchen); and
    2. 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 be constructed of—
      1. wood, particleboard or blockboard not less than 33 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.
  7. A water supply pipe must—
    1. only be installed in the cavity of discontinuous construction; and
    2. in the case of a pipe that serves only one sole-occupancy unit, not be fixed to the wall leaf on the side adjoining any other sole-occupancy unit and have a clearance not less than 10 mm to the other wall leaf.
  8. Electrical outlets must be offset from each other—
    1. in masonry walling, not less than 100 mm; and
    2. in timber or steel-framed walling, not less than 300 mm.

(1) Acceptable forms of construction for masonry walls are set out in (2) to (9).

(2) Two leaves of 110 mm clay brick masonry with—

  1. a cavity of 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C4a.

(3) Two leaves of 110 mm clay brick masonry with—

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

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, when constructed as shown in Figure S28C4b.

(4) A 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 glass or mineral 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C4c.

(5) A 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 glass or mineral 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C4d.

(6) A single leaf of 150 mm brick masonry with 13 mm cement render on each face has an Rw of not less than 50 if constructed as shown in Figure S28C4e.

(7) A single leaf of 220 mm brick masonry with 13 mm cement render on each face has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C4f.

(8) 110 mm thick brick masonry with 13 mm cement render on each face has an Rw of not less than 45 if constructed as shown in Figure S28C4g.

(9) 110 mm thick concrete brickwork has an Rw of not less than 45 if constructed as shown in Figure S28C4h.

Figure S28C4a Two leaves of 110 mm clay brick masonry (method 1)
image-S28C4a-two-leaves-110-mm-clay-brick-masonry-method-1.svg
Figure S28C4b Two leaves of 110 mm clay brick masonry (method 2)
image-S28C4b-two-leaves-110-mm-clay-brick-masonry-method-2.svg
Figure S28C4c Single leaf of 110 mm clay brick masonry
image-S28C4c-single-leaf-110-mm-clay-brick-masonry.svg
Figure S28C4d Single leaf of 90 mm clay brick masonry
image-S28C4d-single-leaf-90-mm-clay-brick-masonry.svg
Figure S28C4e Single leaf of 150 mm brick masonry with 13 mm cement render on each face
image-S28C4e-single-leaf-150-mm-brick-masonry-with-13-mm-cement-render-on-each-face.svg
Figure S28C4f Single leaf of 220 mm brick masonry with 13 mm cement render on each face
image-S28C4f-single-leaf-220-mm-brick-masonry-with-13-mm-cement-render-on-each-face.svg
Figure S28C4g 110 mm thick brick masonry with 13 mm cement render on each face
image-S28C4g-110-mm-thick-brick-masonry-with-13-mm-cement-render-on-each-face.svg
Figure S28C4h 110 mm thick concrete brickwork
image-S28C4h-110-mm-thick-concrete-brickwork.svg

(1) Acceptable forms of construction for concrete walls are set out in (3) to (12).

(2) For the purposes of this clause, the term ‘concrete panel’ is a reference to a solid in-situ concrete panel or solid pre-cast concrete panel.

(3) A 150 mm thick concrete panel has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C5a.

(4) A 150 mm thick concrete panel with one layer of 10 mm plasterboard fixed to 28 mm metal furring channels on each face, has an Rw of not less than 50, if constructed as shown in Figure S28C5b.

(5) A 200 mm thick concrete panel with one layer of 13 mm plasterboard or 13 mm cement render on each face has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C5c.

(6) A 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,

has an with an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed in accordance with Figure S28C5d.

(7) A 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,

has an with an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed in accordance with Figure S28C5e.

(8) A 125 mm thick concrete panel has an Rw of not less than 50, if constructed as shown in Figure S28C5f.

(9) A 100 mm concrete panel with 13 mm cement render or one layer of 13 mm plasterboard on each face has an Rw of not less than 50, if constructed as shown in Figure S28C5g.

(10) A 190 mm thick concrete blockwork has an Rw of not less than 45, if constructed as shown in Figure S28C5h.

(11) 140 mm thick concrete blockwork, the face shell thickness of the blocks being not less than 44 mm and with—

  1. 50 mm x 50 mm timber battens spaced at not more than 610 mm centres screw-fixed on one face of the blocks into resilient plugs with rubber inserts between battens and the wall; and
  2. the face of the battens clad with 13 mm plasterboard,

has an Rw of not less than 45, if constructed as shown in Figure S28C5i.

(12) A concrete panel, 100 mm thick, has an Rw of not less than 45, if constructed as shown in Figure S28C5j.

Figure S28C5a 150 mm thick concrete panel
image-S28C5a-150-mm-thick-concrete-panel.svg
Figure S28C5b 150 mm thick concrete panel with one layer of 10 mm plasterboard fixed to 28 mm metal furring channels on each face
image-S28C5b-150-mm-concrete-panel-10-mm-plasterboard-28-mm-metal-furring-channels.svg
Figure S28C5c 200 mm thick concrete panel with one layer of 13 mm plasterboard or 13 mm cement render on each face
Figure S28C5d 100 mm thick concrete panel with studs, insulation and plasterboard
image-S28C5d-100-mm-concrete-panel-studs-insulation-plasterboard.svg
Figure S28C5e 125 mm thick concrete panel with studs, insulation and plasterboard
image-S28C5e-125-mm-concrete-panel-studs-insulation-plasterboard.svg
Figure S28C5f 125 mm thick concrete panel
image-S28C5f-125-mm-thick-concrete-panel.svg
Figure S28C5g 100 mm concrete panel with 13 mm cement render or one layer of 13 mm plasterboard on each face
image-S28C5g-100-mm-concrete-panel-with-13-mm-cement-render-or-13-mm-plasterboard.svg
Figure S28C5h 190 mm thick concrete blockwork
image-S28C5h-190-mm-thick-concrete-blockwork.svg
Figure S28C5i 140 mm thick concrete blockwork with timber battens and 13 mm plasterboard
image-S28C5i-140-mm-concrete-blockwork-timber-battens-13-mm-plasterboard.svg
Figure S28C5j 100 mm thick concrete panel
image-S28C5j-100-mm-thick-concrete-panel.svg

(1) Acceptable forms of construction for autoclaved aerated concrete walls are set out in (2) to (5).

(2) A 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C6a.

(3) A 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C6b.

(4) 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C6c.

(5) A 75 mm thick autoclaved aerated concrete wall panel with—

  1. one layer of 10 mm moisture resistant plasterboard on one face; and
  2. 28 mm metal furring channels and resilient mounts, 75 mm polyester insulation with a density of 9 kg/m3 and 13 mm fire-protective grade plasterboard fixed to the other face,

has an Rw of not less than 50, if constructed as shown in Figure S28C6d.

Figure S28C6a 75 mm thick autoclaved aerated concrete wall panel (method 1)
image-S28C6a-75-mm-thick-autoclaved-aerated-concrete-wall-panel-method-1.svg
Figure S28C6b 75 mm thick autoclaved aerated concrete wall panel (method 2)
image-S28C6b-75-mm-thick-autoclaved-aerated-concrete-wall-panel-method-2.svg
Figure S28C6c Two leaves of 75 mm autoclaved aerated concrete wall panel
image-S28C6c-two-leaves-75-mm-autoclaved-aerated-concrete-wall-panel.svg
Figure S28C6d 75 mm thick autoclaved aerated concrete wall panel (method 3)
image-S28C6d-75-mm-thick-autoclaved-aerated-concrete-wall-panel-method-3.svg

(1) Acceptable forms of construction for timber and steel framing walls are set out in (2) to (11).

(2) Two rows of 70 x 35 mm timber studs at 450 mm centres with—

  1. an air gap not less than 20 mm between the rows of studs; and
  2. 75 mm thick glass or mineral wool insulation with a density of 8 kg/m³ 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C7a.

(3) One row of 70 mm x 35 mm staggered timber studs, without noggings between adjacent studs, at not less than 450 mm centres, fixed to 90 mm x 35 mm wall plates with—

  1. 75 mm thick glass or mineral wool insulation with a minimum density of 8 kg/m³ positioned between studs; and
  2. two layers of 13 mm fire-protective grade plasterboard fixed to outside face of studs,

has an Rw of not less than 50, if constructed as shown in Figure S28C7b.

(4) One row of 70 mm x 35 mm timber studs at not less than 600 mm centres with—

  1. 75 mm thick glass or mineral wool insulation with a minimum density of 8 kg/m³ positioned between studs; and
  2. two layers of 13 mm fire-protective grade plasterboard fixed to outside face of studs,

has an Rw of not less than 45, if constructed as shown in Figure S28C7c.

(5) One row of 70 mm x 35 mm timber studs at not less than 450 mm centres with—

  1. 28 mm furring channels installed horizontally on one side; and
  2. two layers of 13 mm fire-protective plasterboard fixed on each face,

has an Rw of not less than 45, if constructed as shown in Figure S28C7d.

(6) Two rows of 64 mm steel 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C7e.

(7) 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,

has an Rw + Ctr of not less than 50 and an Rw of not less than 50, if constructed as shown in Figure S28C7f.

(8) One row of 92 mm steel studs at 600 mm centres with—

  1. 50 mm thick glass wool insulation with a density of 11 kg/m3 or 60 mm thick polyester insulation with a density of 8 kg/m3, positioned between studs; and
  2. 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 each face,

has an Rw of not less than 50, if constructed as shown in Figure S28C7g.

(9) One row of 64 mm steel studs with 2 layers of 16 mm fire-protective grade plasterboard fixed to each face has an Rw of not less than 45, if constructed as shown in Figure S28C7h.

(10) One row of 64 mm steel studs with—

  1. one layer of 16 mm fire-protective grade plasterboard fixed to one face; and
  2. 50 mm thick glass or mineral wool insulation with a density of 11 kg/m3 positioned between the studs; and
  3. two layers of fire-protective grade plasterboard fixed to the other face, the inner layer being 16 mm thick and the outer layer being 13 mm,

has an Rw of not less than 45, if constructed as shown in Figure S28C7i.

(11) One row of 64 mm steel studs with two layers of 13 mm plasterboard on each face has an Rw of not less than 45, if constructed as shown in Figure S28C7j.

Figure S28C7a Two rows of 70 mm x 35 mm timber studs
image-S28C7a-two-rows-70-mm-x-35-mm-timber-studs.svg
Figure S28C7b One row of 70 mm x 35 mm staggered timber studs without noggings between adjacent studs
image-S28C7b-one-row-of-70-mm-x-35-mm-staggered-timber-studs-without-noggings.svg
Figure S28C7c One row of 70 mm x 35 mm timber studs at not less than 600 mm centres
image-S28C7c-one-row-of-70-mm-x-35-mm-timber-studs-not-less-than-600-mm-centre.svg
Figure S28C7d One row of 70 mm x 35 mm timber studs at not less than 450 mm centres
image-S28C7d-one-row-of-70-mm-x-35-mm-timber-studs-not-less-than-450-mm-centre.svg
Figure S28C7e Two rows of 64 mm steel studs at 600 mm centres (Method 1)
image-S28C7e-two-rows-of-64-mm-steel-studs-600-mm-centres.svg
Figure S28C7f Two rows of 64 mm steel studs at 600 mm centres (Method 2)
image-S28C7f-two-rows-of-64-mm-steel-studs.svg
Figure S28C7g One row of 92 mm steel studs
image-S28C7g-one-row-92-mm-steel-studs.svg
Figure S28C7h One row of 64 mm steel studs with 2 layers of 16 mm fire-protective grade plasterboard
image-S28C7h-one-row-64-mm-steel-studs-two-layers-16-mm-fire-protective-plasterboard.svg
Figure S28C7i One row of 64 mm steel studs
image-S28C7i-one-row-64-mm-steel-studs.svg
Figure S28C7j One row of 64 mm steel studs with two layers of 13 mm plasterboard on each face
image-S28C7j-one-row-64-mm-steel-studs-two-layers-13-mm-plasterboard-each-face.svg

(1) Acceptable forms of construction for concrete floors are set out in (2) to (4).

(2) 150 mm thick concrete slab with—

  1. 28 mm metal furring channels and isolation mounts fixed to underside of slab, at 600 mm centres; and
  2. 65 mm thick polyester insulation with a density of 8 kg/m3, positioned between furring channels; and
  3. one layer of 13 mm plasterboard fixed to furring channels,

has an Rw + Ctr of not less than 50, an Ln,w of not more than 62 and an Rw of not less than 50, if constructed as shown in Figure S28C8a.

(3) 200 mm thick concrete slab with carpet on underlay has an Rw + Ctr of not less than 50, an Ln,w of not more than 62 and an Rw of not less than 50, if constructed as shown in Figure S28C8b.

(4) 100 mm thick concrete slab has an Rw + Ctr of not less than 45 and an Rw of not less than 45, if constructed as shown in Figure S28C8c.

Figure S28C8a 150 mm thick concrete slab
image-S28C8a-150-mm-thick-concrete-slab.svg
Figure S28C8b 200 mm thick concrete slab with carpet on underlay
image-S28C8b-200-mm-thick-concrete-slab-carpet-underlay.svg
Figure S28C8c 100 mm thick concrete slab
image-S28C8c-100-mm-thick-concrete-slab.svg

(1) An acceptable form of construction for autoclaved aerated concrete floors is set out in (2).

(2) 75 mm thick autoclaved aerated concrete floor panel with—

  1. 8 mm ceramic tiles with flexible adhesive and waterproof membrane, located above the slab; and
  2. timber joists at 600 mm centres; and
  3. R1.5 glass wool insulation positioned between timber joists; and
  4. 28 mm metal furring channels and resilient mounts fixed to underside of joists; and
  5. two layers of 13 mm plasterboard fixed to furring channels,

has an Rw + Ctr of not less than 50, an Ln,w of not more than 62 and an Rw of not less than 50, if constructed as shown in Figure S28C9.

Figure S28C9 75 mm thick autoclaved aerated concrete floor panel
image-S28C9-75-mm-thick-autoclaved-aerated-concrete-floor-panel.svg

(1) Acceptable forms of construction for timber floors are set out in (2) and (3).

(2) 19 mm thick particleboard floor sheeting with—

  1. 190 mm x 45 mm timber joists at 450 mm centres; and
  2. R2.5 glass or mineral wool insulation positioned between timber joists; and
  3. 28 mm metal furring channels and isolation mounts fixed to underside of joists, isolation mounts to be of natural rubber with a dynamic factor of not more than 1.1 and static deflection of not less than 3 mm at actual operating load; and
  4. two layers of 16 mm fire-protective grade plasterboard fixed to furring channels,

has an Rw + Ctr of not less than 50, an Ln,w of not more than 62 and an Rw of not less than 50, if constructed as shown in Figure S28C10a.

(3) Timber flooring with minimum 8.5 kg/m² mass, over 19 mm thick particleboard floor sheeting with—

  1. 190 mm x 45 mm timber joists at not less than 450 mm centres; and
  2. R2.5 glass or mineral wool insulation positioned between timber joists; and
  3. 28 mm metal furring channels fixed to underside of joists at 600 mm centres by clip or mount; and
  4. one layer of 13 mm acoustic grade plasterboard fixed to furring channels,

has an Rw + C of not less than 45 and an Rw of not less than 45, if constructed as shown in Figure S28C10b.

Figure S28C10a 19 mm thick particleboard floor sheeting
image-S28C10a-19-mm-thick-particleboard-floor-sheeting.svg
Figure S28C10b Timber flooring with minimum 8.5kg/m² mass, over 19 mm thick particleboard floor sheeting
image-S28C10b-timber-flooring-over-19-mm-thick-particleboard-floor-sheeting.svg