NCC 2019 Volume One Amendment 1
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Specification F5.2 Sound insulation for building elements
1. Scope
(a)
This Specification lists the weighted sound reduction index Rw for some common forms of construction.
(b)
Wall systems listed in Table 2 having a minimum 20 mm cavity between 2 separate leaves, with—
(i)
for masonry, where wall ties are required to connect leaves, the ties are of the resilient type; and
(ii)
for other than masonry, there is no mechanical linkage between leaves except at the periphery,
are deemed to be discontinuous construction.
Specification F5.2 (in conjunction with Table 2 of Specification F5.2) gives information on the weighted sound reduction index (Rw), weighted sound reduction index with spectrum adaptation term (Rw + Ctr) and weighted normalised impact sound pressure level with spectrum adaptation term (Ln,w) for some common forms of building construction. It also list examples of discontinuous construction.
Further information can be obtained through literature produced by building product manufacturers.
2. Construction Deemed-to-Satisfy
The forms of construction listed in Table 2 for wall construction and Table 3 for floor construction, are considered to have the Rw, Rw + Ctr and Ln,w stated in that Table. The forms of construction must be installed as follows:
(a)
Masonry — Units must be laid with all joints filled solid, including those between the masonry and any adjoining construction.
(b)
Concrete slabs — Joints between concrete slabs or panels and any adjoining construction must be filled solid.
(c)
Sheeting materials—
(i)
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
(ii)
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
(iii)
joints between sheets or between sheets and any adjoining construction must be taped and filled solid.
(d)
Timber or steel-framed construction — perimeter framing members must be securely fixed to the adjoining structure and—
(i)
bedded in resilient compound; or
(ii)
the joints must be caulked so that there are no voids between the framing members and the adjoining structure.
(e)
Services—
(i)
Services must not be chased into concrete or masonry elements.
(ii)
A door or panel required to have a certain Rw + Ctr that provides access to a duct, pipe or other service must—
(A)
not open into any habitable room (other than a kitchen); and
(B)
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—
(aa)
wood, particleboard 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.
(iii)
A water supply pipe must—
(A)
only be installed in the cavity of discontinuous construction; and
(B)
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.
(iv)
Electrical outlets must be offset from each other—
(A)
in masonry walling, not less than 100 mm; and
(B)
in timber or steel-framed walling, not less than 300 mm.
Table 2 Acceptable forms of construction for walls
Description |
Rw+Ctr |
Rw |
Construction |
|---|---|---|---|
Wall construction type: Masonry |
|||
Two leaves of 110 mm clay brick masonry with— (a) cavity not less than 50 mm between leaves; and (b) 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 |
50 |
 |
|
Two leaves of 110 mm clay brick masonry with— (a) cavity not less than 50 mm between leaves and; (b) 13 mm cement render on each outside face. |
50 |
50 |
 |
|
Single leaf of 110 mm clay brick masonry with— (a) a row of 70 mm × 35 mm timber studs or 64 mm steel studs at 600 mm centres, spaced 20 mm from the masonry wall; and (b) 50 mm thick glass or mineral wool insulation with a density of 11 kg/m3 positioned between studs; and (c) one layer of 13 mm plasterboard fixed to outside face of studs and outside face of masonry. |
50 |
50 |
 |
|
Single leaf of 90 mm clay brick masonry with— (a) a row of 70 mm × 35 mm timber studs or 64 mm steel studs at 600 mm centres, spaced 20 mm from each face of the masonry wall; and (b) 50 mm thick glass or mineral wool insulation with a density of 11 kg/m3 positioned between studs in each row; and (c) one layer of 13 mm plasterboard fixed to studs on each outside face. |
50 |
50 |
 |
Single leaf of 150 mm brick masonry with 13 mm cement render on each face. |
- |
50 |
 |
Single leaf of 220 mm brick masonry with 13 mm cement render on each face. |
50 |
50 |
 |
110 mm thick brick masonry with 13 mm cement render on each face. |
- |
45 |
 |
110 mm thick concrete brickwork. |
- |
45 |
 |
Wall construction type: Concrete |
|||
150 mm thick concrete panel. |
50 |
50 |
 |
150 mm thick concrete panel with one layer of 10 mm plasterboard fixed to 28 mm metal furring channels on each face. |
- |
50 |
 |
200 mm thick concrete panel with one layer of 13 mm plasterboard or 13 mm cement render on each face. |
50 |
50 |
 |
100 mm thick concrete panel with— (a) a row of 64 mm steel studs at 600 mm centres, spaced 25 mm from the concrete panel; and (b) 80 mm thick polyester insulation or 50 mm thick glass wool insulation with a density of 11 kg/m³, positioned between studs; and (c) 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 |
50 |
 |
125 mm thick concrete panel with— (a) a row of 64 mm steel studs at 600 mm centres, spaced 20 mm from the concrete panel; and (b) 70 mm polyester insulation with a density of 9 kg/m³, positioned between studs; and (c) one layer of 13 mm plasterboard fixed to the outside face of the studs. |
50 |
50 |
 |
125 mm thick concrete panel. |
- |
50 |
 |
100 mm concrete panel with 13 mm cement render or one layer of 13 mm plasterboard on each face. |
- |
50 |
 |
190 mm thick concrete blockwork. |
- |
45 |
 |
140 mm thick concrete blockwork, the face shell thickness of the blocks being not less than 44 mm and with— (a) 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 |
- |
45 |
 |
Concrete panel - 100 mm thick. |
- |
45 |
 |
|
Note: For the purposes of this table the term "concrete panel" is a reference to a solid in-situ concrete panel or solid precast concrete panel. |
|||
|
Wall construction type: Autoclaved aerated concrete |
|||
|
75 mm thick autoclaved aerated concrete wall panel with— (a) a row of 64 mm steel studs at 600 mm centres, spaced 20 mm from the autoclaved aerated concrete wall panel; and (b) 75 mm thick glass wool insulation with a density of 11 kg/m3 positioned between studs; and (c) 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 |
50 |
 |
|
75 mm thick autoclaved aerated concrete wall panel with— (a) a row of 64 mm steel studs at 600 mm centres, spaced 35 mm from the autoclaved aerated concrete panel wall; and (b) 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 (c) 105 mm thick glass wool insulation with a density of 7 kg/m3 positioned between studs; and (d) one layer of 13 mm fire protective grade plasterboard fixed to the outside face of the studs. |
50 |
50 |
 |
Two leaves of 75 mm autoclaved aerated concrete wall panel with— (a) a cavity not less than 30 mm between panels containing 50 mm glass wool insulation with a density of 11 kg/m3; and (b) one layer of 10 mm plasterboard fixed to outside face of each panel. |
50 |
50 |
 |
|
75 mm thick autoclaved aerated concrete wall panel with— (a) one layer of 10 mm moisture resistant plasterboard on one face; and (b) 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. |
- |
50 |
 |
Wall construction type: Timber and steel framing |
|||
Two rows of 90×35 mm timber studs or two rows of 64 mm steels studs at 600 mm centres with— (a) an air gap not less than 20 mm between the rows of studs; and (b) 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 (c) 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 |
50 |
 |
Two rows of 64 mm steel studs at 600 mm centres with— (a) an air gap not less than 80 mm between the rows of studs; and (b) 200 mm thick polyester insulation with a density of 14 kg/m3; positioned between studs; and (c) 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 |
50 |
 |
One row of 92 mm steel studs at 600 mm centres with— (a) 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 (b) 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. |
- |
50 |
 |
One row of 64 mm steel studs with 2 layers of 16 mm fire-protective grade plasterboard fixed to each face. |
- |
45 |
 |
One row of 64 mm steel studs with— (a) one layer of 16 mm fire-protective grade plasterboard fixed to one face; and (b) 50 mm thick glass or mineral wool insulation with a density of 11 kg/m3 positioned between the studs; and (c) 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. |
- |
45 |
 |
One row of 64 mm steel studs with two layers of 13 mm plasterboard on each face. |
- |
45 |
 |
Table 3 Acceptable forms of construction for floors
Description |
Rw+Ctr (not less than) |
Ln,w (not more than) |
Rw (not less than) |
Construction |
|---|---|---|---|---|
|
Floor construction type: Concrete |
||||
150 mm thick concrete slab with— (a) 28 mm metal furring channels and isolation mounts fixed to underside of slab, at 600 mm centres; and (b) 65 mm thick polyester insulation with a density of 8 kg/m3, positioned between furring channels; and (c) one layer of 13 mm plasterboard fixed to furring channels. |
50 |
62 |
50 |
 |
200 mm thick concrete slab with carpet on underlay. |
50 |
62 |
50 |
 |
100 mm thick concrete slab. |
45 |
- |
45 |
 |
|
Floor construction type: Autoclaved aerated concrete |
||||
75 mm thick autoclaved aerated concrete floor panel with— (a) 8 mm ceramic tiles with flexible adhesive and waterproof membrane, located above the slab; and (b) timber joists at 600 mm centres; and (c) R1.5 glass wool insulation positioned between timber joists; and (d) 28 mm metal furring channels and resilient mounts fixed to underside of joists; and (e) two layers of 13 mm plasterboard fixed to furring channels. |
50 |
62 |
50 |
 |
|
Floor construction type: Timber |
||||
| 19 mm thick chipboard floor sheeting with— (a) 190×45 mm timber joists at 450 mm centres; and (b) R2.5 glass wool insulation positioned between timber joists; and (c) 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 (d) two layers of 16 mm fire-protective grade plasterboard fixed to furring channels. |
50 |
62 |
50 |
 |
| 19 mm thick tongued and grooved boards with— (a) timber joists not less than 175 mm x 50 mm; and (b) 75 mm thick glass or mineral wool insulation with a density of 11 kg/m3 positioned between joists and laid on 10 mm thick plasterboard fixed to underside of joists; and (c) 25 mm thick glass or mineral wool insulation with a density of 11 kg/m3 laid over entire floor, including tops of joists before flooring is laid; and (d) secured to 75 mm × 50 mm battens; and (e) the assembled flooring laid over the joists, but not fixed to them, with the battens lying between the joists. |
45 |
- |
45 |
 |