Part E Sound Calculator — Sound Insulation Requirements

There are three tables. AD E Table 1a covers dwelling-houses and flats and has TWO row groups: purpose built (walls and floors DnT,w + Ctr at least 45 dB, floors and stairs L'nT,w no more than 62 dB) and formed by material change of use (walls and floors at least 43 dB, floors and stairs no more than 64 dB). Conversions of dwellings are the second row group of Table 1a, NOT Table 1b. Table 1b covers rooms for residential purposes: purpose built walls at least 43 dB but floors and stairs at least 45 dB and no more than 62 dB; material change of use 43 dB and no more than 64 dB. Table 2 covers new internal walls and floors within a dwelling and asks for a laboratory Rw of at least 40 dB, with no impact requirement. One override to know: AD E para 0.1 says that for walls separating rooms for residential purposes from adjoining dwelling-houses and flats, the Table 1a standards should be achieved.

Rw is a weighted sound reduction index measured on an element in a laboratory. DnT,w + Ctr is measured in the finished building and includes flanking transmission through the junctions. Tables 1a and 1b are field values; Table 2 is the only table in AD E headed 'Laboratory values' and it covers internal walls and floors only. AD E gives NO conversion between the two, so a laboratory Rw cannot be compared with a Table 1a target. The nearest thing AD E has is Annex B paras B3.13 and B3.14, and they are not a conversion: they say that 49 dB DnT,w + Ctr measured in a FLANKING laboratory is indicative that the same construction may achieve 45 dB in the field, and 58 dB L'nT,w indicative of no more than 62 dB in the field. That is a 4 dB allowance between two measurements of the SAME quantity, and para B3.11 adds that a flanking laboratory result cannot demonstrate compliance with Requirement E1 at all.

No. Neither Section 2 (separating walls), Section 3 (separating floors) nor Section 5 (internal walls and floors) attaches a decibel value to any construction. They give specifications, and paras 0.5, 2.1, 3.1 and 5.1 say those specifications should achieve the relevant table. The only decibel figures on components in those sections are the 29 dB Rw corridor doorset (paras 2.26, 4.20 and 6.6), the 17 dB weighted reduction in impact sound pressure level for a soft floor covering (para 3.28) and the 29 dB weighted reduction for floating floor (c) (para 3.66). None of the three is comparable with Table 1a, 1b or 2. That is why this page reports which construction is listed and what binds it, rather than a predicted rating.

L'nT,w is the standardised impact sound pressure level measured in the finished building: how much impact noise, such as footsteps, passes through a floor. LOWER is better, which is the opposite of the airborne figure, and AD E states it as a MAXIMUM. Table 1a allows no more than 62 dB for a purpose-built separating floor or stair and 64 dB for one formed by material change of use. Separating walls have no impact requirement at all: both Table 1a and Table 1b carry a dash in that column for walls, and Table 2 has no impact column.

For separating walls, separating floors and stairs with a separating function, yes. AD E para 0.2: Regulation 41 of the Building Regulations 2010, or Regulation 20(1) and (5) of the Building (Approved Inspectors etc.) Regulations 2010, requires appropriate sound insulation testing on that work, and para 1.3 lists all four building situations it applies to: purpose built dwelling-houses and flats, dwelling-houses and flats formed by material change of use, purpose built rooms for residential purposes, and rooms for residential purposes formed by material change of use. The one exception is Robust Details, and it is available in ONE of those four. Para 0.2 confines it to 'new-build houses and buildings containing flats', and Annex E condition (a) to work that 'consists of the erection of a new dwelling-house (i.e. a semi-detached or terraced house) or a building containing flats'; Regulation 41(4) uses the same words. So it is not available for any material change of use, and not available for a building of rooms for residential purposes, because Regulation 2 defines a room for residential purposes as one 'which is not a dwelling-house or a flat'. On a new build a builder can use Robust Details on some separating structures and test the rest. Internal walls and floors are different again: they fall under Requirement E2, and para 0.9 says it is not intended that their performance should be verified by testing on site.

Robust Details are constructions approved and published by Robust Details Ltd, whose use removes the Regulation 41 testing obligation for the plots they are notified on, and ONLY on new-build houses and buildings containing flats (AD E para 0.2 and Annex E condition (a)). They are NOT the same thing as the constructions in AD E. AD E names the scheme at para 0.2 and Annex E but reproduces none of its details, so codes of the form E-WM-1 or E-WT-1 are Robust Details references and do not appear anywhere in AD E. This page uses AD E's own codes: wall types 1.1 to 4.1, floor types 1.1C to 3.1A, the Section 4 treatments and internal wall and floor types A to D. One more thing Annex E says that is easy to miss: compliance with a robust detail is not a deemed-to-satisfy condition. The underlying duty is still to comply with E1, and it would not be a defence to show the detail was followed correctly if the measured performance turned out not to meet the standard.

No, and the Limits on application printed beside the Requirement narrow it sharply. E2 covers (a) internal walls between a bedroom or a room containing a water closet, and other rooms, and (b) internal floors. It then does NOT apply to: (a) an internal wall which contains a door; (b) an internal wall which separates an en suite toilet from the associated bedroom; (c) existing walls and floors in a building which is subject to a material change of use. Limit (a) removes most bedroom walls, because the bedroom door is usually in the wall you would want to insulate. AD E still gives advice at para 5.9, but as good practice rather than as a requirement: lightweight doors with poor perimeter sealing lower the effective sound insulation of the wall, so seal the perimeter well or use a doorset. Limit (c) matters in conversions: a retained existing internal wall or floor is outside E2 altogether, while a NEW one built in the same conversion is inside it, because Table 2 is headed 'Laboratory values for new internal walls and floors ... whether purpose built or formed by material change of use'.

Then the table figure is a starting point, not the answer. AD E para 0.8: the standards in Tables 1a and 1b 'are appropriate for walls, floors and stairs that separate spaces used for normal domestic purposes. A higher standard of sound insulation may be required between spaces used for normal domestic purposes and communal or non-domestic purposes. In these situations the appropriate level of sound insulation will depend on the noise generated in the communal or non-domestic space.' A flat over a shop, a bedroom against a plant room, a room next to a bar: AD E sets no number for any of them and says specialist advice may be needed to establish whether a higher standard is required and what it should be. Pre-completion testing will not settle it either, because para 1.8 says testing should not be carried out between living spaces and corridors, stairwells or hallways. Corridor walls and doors have their own guidance at paras 2.25 to 2.27, 4.19 to 4.21 and 6.5 to 6.7.