{
  "url": "https://openlegislation.uk/building-standards-scotland-amendment-regulations-1987/schedule-2",
  "json_url": "https://openlegislation.uk/building-standards-scotland-amendment-regulations-1987/schedule-2.json",
  "legislation": "uksi/1987/1231",
  "legislation_title": "The Building Standards (Scotland) Amendment Regulations 1987",
  "legislation_url": "https://openlegislation.uk/building-standards-scotland-amendment-regulations-1987",
  "path": "schedule/2",
  "kind": "schedule",
  "number": "2",
  "heading": null,
  "text": "SCHEDULE 17\nSpecified constructions and performance standards for resistance to the transmission of sound\nRegulation H3\nPART I: INTERPRETATION OF PART II OF SCHEDULE 17\nArrangement\n1 Walls and floors providing adequate resistance to sound transmission are specified, arranged by construction type. For each type the critical points of workmanship are identified, any limits on use are noted, a set of specified constructions is given, and the junctions with adjoining elements are detailed.\nDimensions\n2 The thicknesses, masses, and other dimensions quoted shall be taken as the minimum required unless otherwise stated. Greater figures are therefore permissible. Note that the timber sizes quoted are actual sizes—therefore a requirement for joists, for example, to be 45 mm wide means that if nominal sizes are used on a drawing 50 mm should be specified.\nCalculating the required mass\n3 Where a mass is specified for walls it is expressed in kilogrammes per square metre of wall face area (kg/m2). For floors the mass is expressed in kilogrammes per square metre on plan (kg/m2).\n4 To calculate the mass of a leaf of masonry the formulae in Table 1 must be used. Densities of bricks or blocks (at 3% moisture content) may be taken from a current Agrément Certificate or from the manufacturer’s literature in which case the building control authority may ask for confirmation, eg that the measurement was done by an accredited test house. Note that the quoted density of bricks or blocks is normally the apparent density, ie the weight divided by the volume including perforations, voids or frogs. This is the density appropriate to the formulae. For co-ordinating heights not in the Table, use the formula for the nearest height. Include plaster or render in calculating the mass, but exclude any dry-lining.\nTable 1: Calculating the mass of masonry leaf\nCo-ordinating height of masonry course (mm)\nformula to be used\n75\nM = T (0.79 D + 380) + NP\n100\nM = T (0.86 D + 255) + NP\n150\nM = T (0.92 D + 145) + NP\n200\nM = T (0.93 D + 125) + NP\nWhere\nM = Mass of 1 m2 of leaf in kg/m2\nT = Thickness of masonry in metres (ie unplastered thickness)\nD = Density of masonry units in kg/m3 (at 3% moisture content)\nN = Number of plastered faces\nP = Mass of 1 m2 of plaster in kg/m2 (see below).\nMass of plaster (assumed thickness 13 mm)\nLightweight\n10 kg/m2\nGypsum\n17 kg/m2\nCement Render\n29 kg/m2\n5 In Table 1 a mortar joint of 10 mm and a dry, set mortar density of 1800 kg/m3 are assumed. Values within 10% of these figures are acceptable.\n6 for in-situ concrete or screeds calculate the mass by multiplying the density (kg/m3) by the thickness (in metres). For slabs or composite floor bases divide the total mass of the element (kg) by the plan area of the element (m2).\nConditions on the use of specified constructions\n7 In any separating wall to which Part II of this Schedule applies, the following conditions must be met:–\n(a) No opening shall be permitted except a doorway between a house and a stairway or passage where the doorway is protected by a fire resisting door satisfying Part D.\n(b) No service pipes or ducts shall pass through a separating wall except between a house and a stairway, passage or duct where the pipe or duct is protected to satisfy Part D.\n(c) Chases for services are allowed in Wall Types 1 or 2 provided they comply with paragraph 19.6 of BS 5628: Part 3: 1985. In Wall Type 3, services may pierce the freestanding panels provided any gaps are sealed with tape or caulking. In order to comply with regulation D7 no services are permitted in Wall Type 4.\n(d) Flues are only permitted in walls where the flue is of masonry construction (including precast concrete flue blocks). No flues are permitted in Wall Type 4.\n8 In any separating floor to which Part II of this Schedule applies no opening is permitted except an opening for a service duct, pipe or flue protected to satisfy Part D or Part F and which is also enclosed to satisfy this Part—ie above and below the floor.\n9 Paragraphs 7 and 8 do not apply to separating walls or floors where the alternative method of compliance (described in Part III of this Schedule) is chosen.\nPART II: SPECIFIED CONSTRUCTIONS\nWall Type 1: Solid Masonry\nThe resistance to airborne sound depends mainly on the mass of the wall.\nPoints to watch\nFill masonry joints with mortar (to achieve the mass and to avoid air paths).\nLimit the pathways around the wall (to reduce flanking transmission).\nConstructions\nFive wall constructions which will give suitable resistance to direct transmission are specified.\nDetails of how junctions must be made to limit flanking transmission follow.\nA Brick, plastered both sides.\nMass including plaster 375 kg/m2.\n13 mm plaster each side.\nLay bricks in a bond which includes headers.\nExample: 215 mm brick, lightweight plaster, 75 mm coursing; brick density of 1610 kg/m3 gives the required mass.\nB Brick, plasterboard both sides.\nMass of masonry alone 395 kg/m2.\n12.5 mm plasterboard each side, use any normal fixing method.\nLay bricks in a bond which includes headers.\nExample: 215 mm brick, 75 mm coursing, brick density of 1845 kg/m3 gives the required mass.\nC Concrete block, plastered both sides.\nMass including plaster 415 kg/m2.\n13 mm plaster each side.\nUse blocks which extend to the full thickness of the wall.\nExample: 215 mm block, lightweight plaster, 110 mm coursing; block density of 1840 kg/m3 gives the required mass.\nD Concrete block, plasterboard both sides.\nMass of masonry alone 415 kg/m2.\n12.5 mm plasterboard each side, use any normal fixing method.\nUse blocks which extend to the full thickness of the wall.\nExample: 215 mm block, 150 mm coursing; block density of 1945 kg/m3 gives the required mass.\nE Concrete, in-situ or large panel.\nPlaster optional.\nDensity 1500 kg/m3.\nMass (including plaster if used) 415 kg/m2.\nFill joints between panels with mortar.\nExample: an unplastered wall of density 2200 kg/m3; 190 mm thickness gives the required mass.\nJunctions\nRoof\nFire-stop the joint between wall and roof.\nCeiling and roof space\nWhere there is a heavy ceiling (12.5 mm plasterboard or equivalent) with sealed joints, the mass of the wall above the ceiling may be reduced to 150 kg/m2. If lightweight blocks are used to reduce mass, seal one side of the wall with cement paint or plaster skim.\nIntermediate and ground floors\nWith a timber floor do not build joists into the wall, use joist hangers.\nWith a concrete floor either the wall or the floor may be carried through.\nExternal wall\nThere must be 650 mm between openings which are on opposite sides of the separating wall.\nThe outer leaf of a cavity external wall may be of any construction.\nAn inner leaf or solid wall must not extend past the end of the separating wall.\nA masonry inner leaf or solid wall must either be bonded to the separating wall or butted to it with ties no more than 300 mm apart vertically. A mass of 120 kg/m2 is required, except where the length of external wall is limited by large openings. (A short length of return wall will not vibrate and cause flanking transmission.) These openings must be at least 1 metre high, be on both sides of the wall at each storey, and be not more than 700 mm from the face of the wall.\nThe 650 mm minimum separation still applies, however.\nA timber inner leaf or external wall must be butted tight against the separating wall with ties no more than 300 mm apart vertically. The joint between the lining to the external wall and the separating wall must be sealed with tape or caulking.\nPartitions\nThere are no restrictions on partition walls meeting a type 1 separating wall.\nWall Type 2: Cavity Masonry\nThe resistance to airborne sound depends on the mass of the leaves and on the degree of isolation achieved.\nPoints to watch\nFill masonry joints with mortar (to achieve the mass and to avoid air paths).\nMaintain the cavity up to the underside of the roof.\nConnect the leaves only where necessary for structural reasons. Use only butterfly pattern ties, spaced 900 mm apart horizontally and 450 mm apart vertically. (BS 5628 limits this tie type and spacing to cavities of 50 mm to 75 mm with a minimum masonry leaf thickness of 90 mm.)\nIf external walls are to be filled with an insulating material other than loose fibre the insulating material must be prevented from entering the cavity in the separating wall.\nConstructions\nTwo wall constructions (A and B) which will give suitable resistance to direct transmission are specified.\nTwo other wall constructions (C and D) will be suitable provided a step and/or stagger is incorporated at the separating wall.\nDetails of how junctions must be made to limit flanking transmission follow.\nA Two leaves of brick with 50 mm cavity, plastered on both room faces.\nMass including plaster 415 kg/m2.\n13 mm plaster each face.\nExample: 102 mm leaves, lightweight plaster, 75 mm coursing; brick density of 1845 kg/m3 gives the required mass.\nB Two leaves of concrete block with 50 mm cavity, plastered on both room faces.\nMass including plaster 415 kg/m2.\nExample: 100 mm leaves, lightweight plaster, 225 mm coursing; block density of 1990 kg/m3 gives the required mass.\nAdditional constructions permitted only where a step and/or stagger is used\nC Two leaves of concrete block with 50 mm cavity, plasterboard on both room faces.\nMass of masonry alone 415 kg/m2.\n12.5 mm plasterboard each face, use any normal fixing method.\nExample: 100 mm leaves, 225 mm coursing; block density of 2100 kg/m3 gives the required mass.\nD Two leaves of lightweight aggregate concrete block (maximum density 1500 kg/m3) with 75 mm cavity, plastered on both room faces.\nMass including plaster 250 kg/m2.\n13 mm plaster each face.\nSeal the face of the blockwork with cement paint or plaster through the full width and depth of any intermediate floor.\nExample: 100 mm leaves, lightweight plaster, 225 mm coursing; block density of 1105 kg/m3 gives the required mass.\nJunctions\nRoof\nFire-stop the joint between wall and roof.\nCeiling and roof space\nWhere there is a heavy ceiling (12.5 mm plasterboard or equivalent) with sealed joints, the mass of the wall above the ceiling may be reduced to 150 kg/m2. The cavity must still be maintained. If lightweight blocks are used to reduce mass one face of the wall must be sealed with cement paint or plaster skim.\nIntermediate and ground floors\nWith a timber floor use joist hangers for any joists supported on the wall.\nWith a concrete intermediate floor carry the floor through only to the cavity face of each leaf.\nWith a concrete ground floor either the wall or the floor may be carried through. A concrete slab on the ground may be continuous.\nExternal wall\nThere must be 650 mm between openings which are on opposite sides of the separating wall.\nThe outer leaf of a cavity external wall may be of any construction.\nAn inner leaf or solid wall must not extend past the end of the separating wall.\nA masonry inner leaf or solid wall must either be bonded to the separating wall or butted to it with ties no more than 300 mm apart vertically, and must have a mass of 120 kg/m2 unless wall B is used when there is no minimum required mass.\nA timber inner leaf or external wall must be butted tight against the separating wall with ties no more than 300 mm apart vertically.\nThe joint between the lining to the external wall and the separating wall must be sealed with tape or caulking.\nPartitions\nThere are no restrictions on partition walls meeting a type 2 separating wall.\nWall Type 3: Solid Masonry between Freestanding Panels\nThe resistance to airborne sound depends on the mass of the core and on the isolation and mass of the panels.\nPoints to watch\nFill masonry joints with mortar (to achieve the mass and to avoid air paths).\nSupport the panels only from floor and ceiling—do not fix or tie them to the masonry core (to maintain isolation).\nMinimum air space between panels and core 25 mm.\nKeep framing clear of core (at least 5 mm).\nConstructions\nFour masonry cores and two panels are specified which in any combination of core plus panels will give suitable resistance to direct transmission. Details of how junctions must be made to limit flanking transmission follow.\nMasonry cores\nA Brick.\nMass 300 kg/m2.\nExample: 215 mm core, 75 mm coursing; brick density of 1290 kg/m3 gives the required mass.\nB Concrete block.\nMass 300 kg/m2.\nExample: 140 mm core, 100 mm coursing; block density of 2195 kg/m3 gives the required mass.\nC Lightweight aggregate concrete block.\nMass 200 kg/m2.\nExample: 140 mm core, 225 mm coursing; block density of 1405 kg/m3 gives the required mass.\nExample: 215 mm core, 150 mm coursing; block density of 885 kg/m3 gives the required mass.\nD Autoclaved aerated concrete block.\nMass 160 kg/m2.\nExample: 200 mm core, 225 mm coursing; block density of 730 kg/m3 gives the required mass.\nPanels\nE Two sheets of plasterboard joined by a cellular core.\nMass (including plaster finish if used) 18 kg/m2.\nFix to ceiling and floor only.\nTape joints between panels.\nF Two sheets of plasterboard.\nThickness of each sheet 12.5 mm if a supporting framework is used, or total thickness of 30 mm if no framework is used.\nStagger joints.\nJunctions\nRoof\nFire-stop the joint between masonry core and roof.\nCeiling and roof space\nWhere there is a heavy ceiling (12.5 mm plasterboard or equivalent) with sealed joints, the freestanding panels may be omitted in the roof space and the mass of the core above the ceiling may be reduced to 150 kg/m2. If lightweight blocks are used to reduce mass, seal one side with cement paint or plaster skim. Seal the gap between the ceiling and the masonry core with a timber batten, and the gap between ceiling and freestanding panels with tape or caulking.\nIntermediate and ground floors\nWith a timber intermediate floor use joist hangers for any joists supported on the wall and seal the spaces between joists with full depth timber battens.\nWith a concrete intermediate floor the floor base may only be carried through where it has a mass of 365 kg/m2. Seal the gap between ceiling and panel with tape or caulking.\nThe ground floor must be a solid slab, laid on the ground (to prevent air paths).\nExternal wall\nThere must be 650 mm between openings which are on opposite sides of the separating wall.\nInternal finish to the external wall must be freestanding panels of the type specified for the separating wall except, for cores A or B only, dry-lining with joints sealed with tape or caulking may also be used. A layer of insulation may be added to panels lining the external wall provided the 25 mm and 10 mm gaps shown on the diagram are maintained. If freestanding panels are used the external wall may be of any material. If dry-lining is used, the external wall leaf must be masonry with a mass of 120 kg/m2, butt jointed to the separating wall core with ties no more than 300 mm apart vertically.\nPartitions\nPartitions abutting a type 3 separating wall must not be of masonry construction.\nOther loadbearing partitions should be fixed to the masonry core through a continuous pad of mineral fibre quilt.\nNon-loadbearing partitions should be tight butted to the freestanding panels.\nAll joints between partitions and panels must be sealed with tape or caulking.\nWall Type 4: Timber Frames with Absorbent Curtain\nThe resistance to airborne sound depends on the isolation of the frames plus absorption in the air space between.\nLimitations\nThis type is limited to use between houses up to three storeys high excluding flats or maisonettes. (See Part D of the regulations, Structural Fire Precautions.) Use in flats and maisonettes is permitted by Class Relaxation Number 75, subject to certain conditions. The special walls specified in the Relaxation, for stairways, are suitable to resist sound transmission provided isolation of the leaves is maintained.\nPoints to watch\nOnly connect frames if necessary for structural reasons, and then use as few ties as possible—not more than 14–16 gauge (40 mm × 3 mm) metal straps fixed at or just below ceiling level, 1.2 m apart.\nServices must not be contained in the wall. This is a structural fire precaution but also prevents the creation of air paths through the lining. Where fire-stops are needed in the cavity between frames they must either be flexible or fixed to only one frame.\nConstructions\nTwo constructions which with appropriate cladding and absorbent will give suitable resistance to direct transmission are specified. Details of how junctions must be made to limit flanking transmission follow.\nBasic construction\nA Timber frames, 200 mm between claddings, plus absorbent curtain in cavity.\nPlywood sheathing may be used in the cavity as necessary for structural reasons.\nB Timber frames, masonry core, plus absorbent curtain in a cavity. Claddings 200 mm apart (ignore core). Framing must be clear of core (at least 5 mm).\nMasonry core\nC This does not normally improve sound resistance, but may be useful for support and in stepped or staggered situations. There are no restrictions on type of core but the core may be connected to more than one frame.\nCladding\nD On each side: two or more layers of plasterboard, combined thickness 30 mm, joints staggered to avoid air paths.\nAbsorbent curtain\nE Unfaced mineral fibre quilt (which may be wire reinforced), density 12–36 kg/m3, thickness 25 mm if suspended in the cavity between frames, 50 mm if fixed to one frame, or 25 mm per quilt if one fixed to each frame.\nJunctions\nRoof\nFire-stop the joint between wall and roof.\nCeiling and roof space\nCarry the complete construction through to the underside of the roof. Provision of a ceiling of any type is optional.\nIntermediate floor and ground floor\nBlock the air path to the wall cavity either by carrying the cladding through the floor or by using a solid timber edge to the floor. Where the joists are at right angles to the wall seal spaces between joists with full depth timber battens.\nExternal wall\nThere must be 650 mm between openings which are on opposite sides of the separating wall.\nThere are no restrictions on the external cladding to a timber frame wall leaf but if an external leaf is used the cavity between the end of the wall frames and the outer leaf must be filled so as to seal air gaps.\nInternal finishes to external wall. Use lining of 12.5 mm plasterboard or other equally heavy material. (Resilient layers for thermal insulation may be incorporated if desired.)\nPartitions\nThere are no restrictions on partitions meeting a Type 4 separating wall.\nFloor Type 1: Concrete Base with Soft Covering\nThe resistance to airborne sound depends on the mass of the concrete base and on eliminating air paths. The soft covering reduces impact sound at source.\nLimitations\nWhere resistance to airborne sound only is required the soft covering may be omitted.\nNo other part of the construction may be altered or omitted as this would reduce airborne sound resistance.\nPoints to watch\nFill all joints between parts of the floor (to avoid air paths).\nLimit pathways around the floor (to reduce flanking transmission).\nWorkmanship and detailing must be good at the perimeters and wherever the floor is penetrated by a pipe or duct (to reduce flanking transmission and to avoid air paths).\nConstructions\nFour floor bases which will give suitable resistance to direct transmission of airborne sound are specified, followed by the soft covering which must be added to any of the four to give suitable resistance to impact sound transmission.\nDetails of how junctions must be made to limit flanking transmission follow.\nFloor bases\nA Solid concrete slab (in-situ).\nFloor screed and/or ceiling finish optional.\nMass (including any bonded screed and/or ceiling finish) 365 kg/m2.\nB Solid concrete slab with permanent shuttering. Floor screed and/or ceiling finish optional.\nMass (including shuttering only if it is solid concrete or metal, and including any bonded screed and/or ceiling finish) 365 kg/m2.\nC Concrete beams with infilling blocks.\nFloor screed must be used.\nCeiling finish optional.\nMass of beams, blocks and screed (including any bonded ceiling finish) 365 kg/m2.\nD Concrete planks (solid or hollow).\nFloor screed must be used.\nCeiling finish optional.\nMass of planks plus screed (including any bonded ceiling finish) 365 kg/m2.\nSoft covering\nE Any resilient material, or material with a resilient base, with an overall uncompressed thickness of 4.5 mm. Suitable resilience will also be provided by a floor covering with a weighted impact sound improvement index (Δ Lw) of 17 as calculated in Annex A to BS 5821: Part 2: 1984. The soft covering must be bonded to the floor base.\nJunctions\nExternal wall or cavity separating wall\nThe mass of any solid wall or inner leaf of a cavity wall adjoining the floor must be 120 kg/m2 (including any plaster) except, where the area of openings in the external wall exceeds 20% of its area, there is no minimum mass.\nThe floor base (excluding any screed, even in C or D) must pass through the wall whether spanning parallel to or at right angles to the wall. Do not bridge a cavity.\nInternal wall or solid separating wall\nIf the wall mass is less than 355 kg/m2 (including any plaster) the floor base (excluding any screed) must pass through.\nIf the wall mass is more than 355 kg/m2 (including any plaster) either the wall or the floor base (excluding any screed) may pass through. Where the wall does pass through tie the floor base to the wall and grout the joint.\nFloor penetrations\nDucts or pipes penetrating the floor must be in a duct enclosure, both above and below the floor.\nEither line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral fibre.\nThe material of the enclosure must have a mass of 15 kg/m2 (and be non-combustible in certain cases—see regulation D12).\nFlexible fire-stopping must be used where the pipe or duct passes through the floor.\nWhere permitted by regulation D11, a flue-pipe may penetrate the floor. Unless the flue-pipe dis>dh\ncharges into a flue within a chimney carried by the floor, a non-combustible enclosing duct with mineral fibre absorbent must be provided.\nFloor Type 2: Concrete Base with Floating Layer\nThe resistance to airborne sound depends mainly on the mass of the concrete base and partly on the mass of the floating layer.\nResistance to impact sound depends on a resilient layer isolating the floating layer from the base and from the surrounding construction.\nLimitations\nWhere resistance to airborne sound only is required the full construction must still be used.\nResilient layers need not be used under kitchen or sanitary fittings, or in cupboards or wardrobes.\nPoints to watch\nFill all joints between parts of the floor base (to avoid air paths).\nLimit the pathways around the floor (to reduce flanking transmission).\nWorkmanship and detailing must be good at the perimeters and wherever the floor is penetrated (to reduce flanking transmission and to avoid air paths).\nTake care not to create a bridge between the floating layer and the base, surrounding walls, or adjacent screeds.\nWith bases C and D a screed is recommended where differences in camber might cause bridging of the resilient layer and where the top chord of a trough section is less than 50 mm thick (to prevent areas of reduced resistance).\nConstructions\nFour floor bases, two floating layers and one resilient layer are specified and will in any combination of base, resilient layer and floating layer give suitable resistance to direct transmission. Two additional resilient layers which may be used only under screeds are specified also (H and I). Details of how junctions must be made to limit flanking transmission follow.\nFloor bases\nA Solid concrete slab (in-situ).\nFloor screed and/or ceiling finish optional.\nMass (including any bonded screed and/or ceiling finish) 300 kg/m2.\nB Solid concrete slab with permanent shuttering.\nFloor screed and/or ceiling finish optional.\nMass (including shuttering only if it is solid concrete or metal, and including any bonded screed and/or ceiling finish) 300 kg/m2.\nC Concrete beams with infilling blocks.\nFloor screed and/or ceiling finish optional.\nMass of beams and blocks (including any bonded screed or ceiling finish) 300 kg/m2.\nD Concrete planks (solid or hollow).\nFloor screed and/or ceiling finish optional.\nMass of planks (including any bonded screed or ceiling finish) 300 kg/m2.\nFloating layers\nE Timber raft.\nTimber boarding or wood based board, 18 mm thick and with tongued and grooved edges, fixed to 45×45 mm battens. The raft must be laid loose on the resilient layer.\nF Screed.\n65mm cement/sand screed or 40 mm anhydrite screed, with mesh reinforcement.\nResilient layer\nG 25 mm mineral fibre, density 36 kg/m3, covering the whole area of the floor. A 13 mm thickness may be used under a timber raft if the battens used have an integral closed cell resilient foam strip.\nLay the fibre rolls tightly butted, and turned up at the edges of floating layer.\nUnder a timber raft, fibre may be paper faced on the underside.\nUnder a screed, fibre must be paper faced on upper side (to prevent screed entering the layer).\nAdditional resilient layers for use only under screeds\nH 13 mm pre-compressed expanded polystyrene board (impact sound duty grade). Lay boards tightly butted, use on edge as a resilient strip at edges of floating screed.\nI 5 mm extruded (closed cell) polyethylene foam, density 30–45 kg/m3. Lay with joints lapped. Turn up at edges of floating screed.\nJunctions\nExternal wall or cavity separating wall\nThe mass of any solid wall or inner leaf of a cavity wall adjoining the floor must be 120 kg/m2 (including any plaster) except, where the area of openings in the external wall exceeds 20% of its area, there is no minimum mass.\nThe floor base (excluding any screed) must pass through the wall whether spanning parallel to or at right angles to the wall. Do not bridge a cavity.\nCarry the resilient layer up at all edges to isolate the floating layer.\nLeave a 3 mm gap between skirting and floating layer or turn resilient layer under skirting. A seal is not necessary but if used must be flexible.\nInternal wall or solid separating wall\nIf the wall mass is less than 355 kg/m2 (including any plaster) the floor base (excluding any screed) must pass through.\nIf the wall mass is more than 355 kg/m2 (including any plaster) either the wall or the floor base (excluding any screed) may pass through.Where the wall does pass through, tie the floor base to the wall and grout the joint.\nFloor penetrations\nDucts or pipes penetrating the floor must be in a duct enclosure, both above and below the floor.\nEither line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral fibre.\nThe material of the enclosure must have a mass of 15 kg/m2 (and be non-combustible in certain cases—see regulation D12).\nLeave a 3 mm gap between enclosure and floating layer, and seal with acrylic caulk or neoprene.\nFlexible fire-stopping must be used where the pipe or duct passes through the floor.\nWhere permitted by regulation D11, a flue-pipe may penetrate the floor. Unless the flue-pipe discharges into a flue within a chimney carried by the floor, a non-combustible enclosing duct with mineral fibre absorbent must be provided.\nFloor Type 3: Timber Base with Floating Layer\nThe resistance to airborne sound depends partly on the structural floor plus absorbent blanket or deafening (pugging), and partly on the floating layer. Resistance to impact sound depends on a resilient layer isolating the floating layer from the base and the surrounding construction.\nLimitations\nWhere resistance to airborne sound only is required the full construction must still be used.\nThis type of floor is limited to use in a building not more than four storeys in height where the fire resistance satisfies Part D of the regulations. This type can also be used as a specified construction for converted properties. Use is only permitted with appropriate supporting walls (see “Junctions” below).\nPoints to watch\nLimit the pathways around the floor (to reduce flanking transmission).\nWorkmanship and detailing must be good at the perimeter and wherever the floor is penetrated (to reduce flanking transmission and to avoid air paths).\nThe density of the resilient layer is important.\nTake care not to bridge between the floating layer and the base or surrounding walls (eg with services or fixings which penetrate the resilient layer). Allow for movement of materials eg expansion of chipboard after laying (to maintain isolation).\nConstructions\nThree complete constructions which will give suitable resistance to direct sound transmission are specified. Note that there are some alternatives within each construction. Details of how junctions must be made to limit flanking transmission follow.\nFloors\nA Platform floor with absorbent blanket.\nFloating layer of either timber boarding or wood-based board, 18 mm thick and with tongued and grooved edges, spot bonded to substrate of 19 mm plasterboard, or two layers of cement bonded particle board, each 6 mm thick, joints staggered, glued and screwed together.\nResilient layer of 25 mm mineral fibre, density 60–80 kg/m3.\nFloor base of 12 mm timber boarding or wood-based board nailed to timber joists (size to suit structure).\nCeiling of two layers of plasterboard, with joints staggered, total thickness 30 mm, with an absorbent blanket of 100 mm unfaced mineral fibre, density 12–36 kg/m2, laid on the ceiling.\nB Heavy ribbed floor with absorbent blanket or deafening (pugging)*.\nFloating layer of timber boarding or wood-based board, 18 mm thick and with tongued and grooved edges (joints to be glued), on substrate of 19 mm plasterboard nailed to 45 mm×45 mm timber battens placed on joists.\nResilient strips of 25 mm mineral fibre, density 70–140 kg/m3, laid on joists.\nFloor base of 45 mm timber joists.\nCeiling of either two layers of plasterboard with joints staggered, total thickness 30 mm, with an absorbent blanket of 100 mm unfaced mineral fibre, density 12–36 kg/m3, laid on the ceiling; or 6 mm plywood fixed under joists plus two layers of plasterboard with joints staggered, total thickness 30 mm, with deafening (pugging) of mass 50 kg/m2 on a polyethylene liner.\nC Ribbed floor with heavy deafening (pugging)*.\nFloating layer of timber boarding or wood-based board, 18 mm thick and with tongued and grooved edges (joints to be glued), nailed to 45 mm×45 mm timber battens placed either on or between joists.\nResilient strips of 25 mm mineral fibre, density 70–140 kg/m3, laid on joists.\nFloor base of 45 mm timber joists.\nCeiling of either 19 mm dense plaster on expanded metal lath or 6 mm plywood fixed under the joists plus two layers of plasterboard with joints staggered, total thickness 25 mm.\nBoth types of ceiling to have deafening (pugging) of mass 80 kg/m2 laid on a polyethylene liner.\n*Deafening (pugging) may be of the following types:–\nTraditional ash (75 mm);\n2–10 mm limestone chips (60 mm);\n2–10 mm whin aggregate (60 mm);\nDry sand (50 mm).\nFigures in brackets show approx thickness required to achieve 80 kg/m2.\nDo not use sand in kitchens, bathrooms, water closets or utility rooms.\nJunctions\nTimber frame wall\nSeal the gap between wall and floating layer with a resilient strip glued to the wall.\nLeave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible.\nBlock air paths between the floor base and the wall, including the space between joists when joists are at right angles to the wall.\nSeal the junction of ceiling and wall lining with tape or caulking.\nHeavy masonry leaf\nMass of leaf (including any plaster) 355 kg/m2, both above and below floor.\nSeal the gap between wall and floating layer with a resilient strip glued to the wall.\nLeave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible.\nUse any normal method of connecting floor base to wall.\nSeal the junction of ceiling and wall lining with tape or caulking.\nLight masonry leaf\nIf the mass (including any plaster) is less than 355 kg/m2 a freestanding panel as specified in Wall Type 3 must be used.\nSeal the gap between wall and floating layer with a resilient strip glued to the freestanding panel.\nLeave a 3 mm gap between skirting and floating layer. A seal is not necessary but if used must be flexible.\nUse any method of connecting floor base to wall, but block air paths between floor and wall cavities.\nTake ceiling through to masonry, seal junction with freestanding panel with tape or caulking.\nFloor penetrations\nDucts or pipes penetrating the floor must be in a duct enclosure both above and below the floor.\nEither line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral fibre.\nThe material of the enclosure must have a mass of 15 kg/m2 (and be non-combustible in certain cases—see regulation D12).\nLeave a 3 mm gap between enclosure and floating layer, seal with acrylic caulk or neoprene. (Enclosure may go down to the floor base if specification A is used, but maintain isolation of enclosure from floating layer.)\nFlexible fire-stopping must be used where the pipe or duct passes through the floor.\nWhere permitted by regulation D11, a flue-pipe may penetrate the floor. The flue-pipe must be in a non-combustible enclosing duct with mineral fibre absorbent.\nSeal the junction of ceiling and enclosure with tape or caulking.\nFloor Type 4: Timber Base with Independent Ceiling\nThe resistance to airborne and impact sound depends mainly on the mass and isolation of the independent ceiling, and partly on the mass of the floor base.\nLimitations\nWhere resistance to airborne sound only is required the full construction must still be used.\nThis type is limited to use in a building not more than four storeys in height where the fire resistance satisfies Part D of the regulations.\nIt must be used only with heavy masonry walls. It is mainly for use as a specified construction for converted properties with suitable existing floors and walls.\nPoints to watch\nLimit the pathways around the floor, especially at the edges of the independent ceiling (to reduce flanking transmission and to avoid air paths).\nWorkmanship and detailing must be good wherever the floor is penetrated.\nTake care not to create bridges between the floor base and the independent ceiling.\nConstruction\nThe construction specified below will give suitable resistance to direct sound transmission.\nDetails of how junctions must be made to limit flanking transmission follow.\nFloor\nTimber boarding or wood-based board, 18 mm thick with tongued and grooved edges (or overlaid with 3.2 mm hardboard to seal gaps).\n45 mm joists plus deafening (pugging) of mass 80 kg/m2 and a ceiling of either 19 mm dense plaster on lath or two layers of plasterboard with joints staggered, total thickness 30 mm. In existing floors deafening may be on boards between joists, in new floors use 6 mm plywood fixed to underside of joists. (A polyethylene liner may be used if desired.)\nIndependent ceiling\nAbsorbent blanket of 25 mm unfaced mineral fibre, density 12–36 kg/m2, draped over 45 mm joists supported independently of the floor. Ceiling of two layers of plasterboard with joints staggered, total thickness 30 mm. Keep ceiling 150 mm away from the floor base underside.\nJunctions\nExternal wall or separating wall\nMass of leaf must be 355 kg/m2 (including any plaster), both above and below the floor, on at least 3 sides. Leaf on fourth side must be at least 180 kg/m2.\nUse bearers on walls (fixed through mineral fibre strip) to support the edges of the ceiling and to block air paths.\nSeal the junction of ceiling and wall with tape or caulking.\nInternal wall\nIf masonry, mass must be 180 kg/m2.\nNo restriction if stud partition.\nSupport and edge ceiling as for external walls.\nFloor penetrations\nDucts or pipes penetrating the floor must be in a duct enclosure both above and below the floor.\nEither line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral fibre.\nThe material of the enclosure must have a mass of 15 kg/m2 (and be non-combustible in certain cases—see regulation D12).\nFlexible fire-stopping must be used where the pipe or duct passes through the floor.\nWhere permitted by regulation D11, a flue-pipe may penetrate the floor. The flue-pipe must be in a non-combustible enclosing duct with mineral fibre absorbent.\nSeal the junction of ceiling and enclosure with tape or caulking.\nPART III: PERFORMANCE STANDARDS AND TEST PROCEDURES\n1 When a construction other than a specified construction from Part II is used, the following performance standards will indicate adequate resistance to sound transmission.\nAirborne Sound\nMinimum values of weighted standardised level difference (DnT,w)\nMean Value\nIndividual Value\nWalls\n53\n49\nFloors\n52\n48\nImpact Sound\nMaximum values of weighted standardised impact sound pressure level (L'nT,w)\nMean Value\nIndividual Value\nFloors\n61\n65\n2 Performance of a wall or floor will be adequate if the above values are achieved when the following test programme is carried out.\nTest Procedures\n(i) for each wall or floor which requires to be tested take four sets of measurements, or as close to four as possible given the following restrictions:–\n(a) for each set of measurements use a pair of rooms if possible (room is as defined in regulation A5(1)());\n(b) use a pair consisting of a room and some other space only where necessary to make up the four sets;\n(c) use a pair consisting of spaces other than rooms only where no other measurement is possible (results from such a pair must not be used in conjunction with any other set of measurements);\n(d) take only one set of measurements between each pair.\n(ii) When measuring between a pair of rooms of unequal area, the sound source must be in the larger room.\n(iii) When measuring between a room and some other space, the sound source must be in the other space.\n(iv) Carry out the tests for airborne sound in accordance with BS 2750: Part 4:\n1980, and for impact sound in accordance with BS 2750: Part 7: 1980. The tests are to be made in completed but unfurnished houses. Doors and windows must be closed. The tests will determine the standardised level differences (DnT) for airborne sound transmission and the standardised impact sound pressure levels (L'T) for impact sound transmission.\n(v) for each set of measurements calculate the weighted standardised level difference (DnT,w) in accordance with BS 5821: Part 1: 1984 or the weighted standardised impact sound pressure level (L'nT,w) in accordance with BS 5821: Part 2: 1984.\n(vi) The calculated value from each set of measurements must be no worse than that stated in the “individual value” column in paragraph 1.\n(vii) The mean of the four* calculated values must be no worse than that stated in the “mean value” column in paragraph 1.\n*(where only two or three sets of measurements have been possible the mean must still be reached, and where only one set is possible the value achieved must not be worse than the mean value).\n3 In any building every separating wall or floor, or part of a separating wall or floor, with nominally identical construction may be regarded as forming part of a single wall or floor—eg in a block of flats a wall rising through several storeys may be regarded as a single wall, and separating floors over a whole storey may be regarded as a single floor, wherever the flat plans are nominally identical.\n4 A separating wall which changes construction only in a roofspace may be regarded as a single wall.\n5 In any group of houses covered by one building warrant separating walls and floors of nominally identical house types which are similarly situated in regard to adjoining buildings may all be regarded as meeting the performance standard if any one of these walls or floors meets the standard when tested as in paragraph 2 of this Part.\nGeneral Note\nThe test procedure in Part III of this Schedule is intended to provide evidence that a particular wall or floor satisfies the performance standard required by regulation H3(4)(b).\nA specified construction does not have to meet the performance standard.\nA building control authority which uses testing to assess the standard of workmanship of specified constructions may regard any result falling below that required of an individual value in the performance standard as indicating faulty workmanship.",
  "extent": null,
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "footnote",
      "label": "f1",
      "text": "The definition of “room” in regulation A5(1) was amended by S.I. 1986/1278."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/uksi/1987/1231/schedule/2",
    "retrieved_at": "2026-10-29T16:23:45.663811+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}