Acoustics for wood floors: Part E impact sound and build-ups

At a glance

Impact: lower is better. L'nT,w is the level in the room below with a tapping machine above. Each figure is the limit for the floor between two rooms, tested on site. Northern Ireland was not read.

The numbers, and which rooms they cover

A hotel bedroom is a room for residential purposes under the Building Regulations. The definition, reproduced in Approved Document E, takes in a room in a hostel, hotel, boarding house, hall of residence or residential home, and leaves out a patient room in a hospital or similar. Requirement E1 asks for reasonable resistance to sound from other parts of the building. Table 0.1b sets the figures for the floors and stairs that separate such rooms, and Table 0.1a the same for flats.

The impact figure is a maximum: L’nT,w, the level of a tapping machine in the room above as heard in the room below, corrected for the reverberation time of the room. A lower figure is better. For a purpose-built room it is 62 dB, and 64 dB where the room was formed by a change of use. The airborne figure is a minimum (DnT,w + Ctr): 45 dB for a floor between purpose-built rooms and 43 dB for a conversion. The Welsh Government's edition of the Document has the same Table 0.1b. Scotland's non-domestic handbook sets stricter figures for impact: 56 dB, or 58 dB for conversions of traditional buildings. Northern Ireland has its own booklet, which we did not read.

• The floor above a bar or restaurant. Paragraph 0.8 says the table values suit spaces used for normal domestic purposes, and that a higher standard may be needed between those and communal or non-domestic spaces. It calls for specialist advice.
• No shortcut for hotels. Robust Details, the alternative to testing, is described in paragraph 0.2 for new-build houses and buildings containing flats. A room for residential purposes is tested. The Document's introduction says pre-completion testing has applied to them since 1 July 2003.
• Corridors are a separate requirement, E3 (reverberation). See specifying timber floors for high-traffic interiors.

How the number is proved: the pre-completion test

Compliance is shown by a test on site, on the floor as built. Nobody can certify a wood floor, or an underlay, for Part E on its own. Approved Document E (England) describes the pre-completion test like this.

Annex B names carpet and foam-backed vinyl as soft coverings. It does not say how a timber floor, or a timber floor on an underlay, is to be treated at test. Ask the acoustician and the building control body before the programme is set, since it decides whether the floor finish is down on test day.

The test standards have moved on. Approved Document E names BS EN ISO 140-7:1998 for the field measurement, BS EN ISO 140-8:1998 for laboratory tests on coverings and BS EN ISO 717-2:1997 for rating. BSI lists those three as withdrawn (31 December 2015, 28 February 2011 and 31 March 2013), and lists BS EN ISO 16283-2:2020, BS EN ISO 10140-3:2021 and BS EN ISO 717-2:2020 as current. Which editions a test report should follow is for the acoustician and building control.

A maker's figure is not the site result

A maker's number is nearly always a laboratory figure, and a laboratory figure is not the site result. The Document's glossary defines ΔLw as the measured improvement in impact sound insulation from a floor covering or floating floor on a test floor in a laboratory. L’nT,w is the result for the whole floor as built.

Annex B adds two cautions. A flanking laboratory can include the walls, and a build-up that reaches 58 dB L’nT,w or less there is, per the Document, indicative that the same construction may reach 62 dB on site, but a flanking laboratory result cannot be used to demonstrate compliance (B3.11, B3.14).

The build-ups Approved Document E describes

Approved Document E gives examples of floors that, built correctly, should meet the tables. They are not exhaustive: other designs may be used with advice from the manufacturer or another source (3.2, 6.3). For rooms for residential purposes (6.8), the most suitable new-build floors are types 1.1C and 1.2B, a concrete base with a soft covering. Types 2 and 3, with floating floors, can be used provided the floating floors and ceilings are not continuous between rooms for residential purposes, and specialist advice may be needed.

The finished timber floor is not part of those descriptions, except where it is the soft covering of type 1, or part of a floating floor assessed by performance (c). The Document's second route for a soft covering is a tested ΔLw of at least 17 dB (3.28). So a timber floor with a tested system figure may be a route to type 1; whether a given system counts is for the acoustician and building control. That is our reading.

Edges and details: where floors fail

Most failures are in the details, not the layers. The Document's ‘points to watch’ for floating floors and platform floors (3.63, 3.99, 4.34) are:

• leave a small gap, as the manufacturer advises, between the floating layer and the wall at every room edge, and fill it with flexible sealant;
• leave a gap of about 5 mm between the skirting and the floating layer, filled with flexible sealant;
• lay resilient material in rolls or sheets with lapped joints, or tightly butted and taped; use paper facing on the upper side of fibrous material so screed cannot enter it;
• carry the resilient layer up at all room edges, to isolate the floating layer from the wall;
• allow for movement of materials, for example the expansion of chipboard after laying;
• do not bridge between the floating layer and the base or the walls, for example with services or fixings that pass through the resilient layer.

For a timber floor, the movement gap at the edge and the acoustic gap are the same gap: keep rigid fixings, packers and fillers out of it. That is our reading, not the Document's. For the movement gap and the thresholds see floor transitions and movement joints, and for the screed beneath subfloor requirements for wood flooring. The depth all these layers add is on floor build-up heights and finished floor levels.

Floor between [rooms for residential purposes] to achieve impact sound insulation L'nT,w not more than [62] dB [64 dB where formed by material change of use] and airborne sound insulation DnT,w + Ctr not less than [45] dB [43 dB], as Approved Document E Table 0.1b, [and not more than [ ] dB / not less than [ ] dB, as set by [acoustician] for the floor above [bar or restaurant]]. [Scotland: not more than 56 dB.]

Floor build-up: [Approved Document E floor type [2.1C] with floating floor [(b)] and ceiling treatment [C] / acoustician's design [ref]]. Concrete base not less than [300] kg/m²; resilient layer [mineral wool 25 mm, 36 kg/m³ / [type], dynamic stiffness not more than [15] MN/m³ and thickness not less than [5] mm to BS EN 29052-1]; floating layer [65 mm sand-cement screed, not less than 80 kg/m²]; finish [engineered timber, [ ] mm, [bonded / floated]].

The floating floor or covering to have a ΔLw of not less than [ ] dB, tested with the finished floor, adhesive and underlay proposed, loaded and unloaded, on a [140] mm test floor by a UKAS accredited laboratory, to [BS EN ISO 10140-3 and BS EN ISO 717-2, current editions / editions agreed with building control]. Report dated [ ] to be submitted before ordering.

Pre-completion testing by a [UKAS accredited / ANC registered] test body to Approved Document E Annex B, at the rate set by [building control body], in rooms complete except decoration, unfurnished, doors closed. Resilient layer turned up at all room edges; gap [ ] at the wall and [5] mm under skirtings, filled with flexible sealant; resilient joints lapped or butted and taped; no fixing or service to pass through the resilient layer.

Standards and sources

• Approved Document E: Resistance to the passage of sound (England; 2003 edition, reprint October 2015): Table 0.1b (p.12); Sections 0, 1, 3, 4, 6; Annex B. Paragraphs cited in the text. Read 5 Nov 2026.
• Approved Document E frequently asked questions (DCLG, March 2016): read 5 Nov 2026.
• Welsh Government: Approved Document E: Table 0.1b (p.19) read 5 Nov 2026.
• Scotland: building standards technical handbook 2022, non-domestic, section 5.1: clause 5.1.2, Table 5.1; published 1 Jun 2022; read 5 Nov 2026.
• BS EN ISO 16283-2:2020, BS EN ISO 10140-3:2021, BS EN ISO 717-2:2020, BS EN 29052-1:1992: BSI Knowledge listings: Current. BS EN ISO 140-7:1998, 140-8:1998 and 717-2:1997, named in the Document, are withdrawn. Standards not read.

Questions we are asked

What impact sound must a hotel bedroom floor meet?

In England and Wales, Approved Document E Table 0.1b gives a maximum of 62 dB L'nT,w for floors between purpose-built rooms for residential purposes, which include hotel rooms, and 64 dB where the room was formed by a change of use. Lower is better. Scotland's non-domestic handbook gives 56 dB, or 58 dB for conversions of traditional buildings.

Does a wood floor fail Part E?

Not by being wood. The test is on the floor as built, and the build-up decides. Approved Document E describes floors with a concrete base, a resilient layer and a floating layer that are expected to meet the tables, and leaves room for other designs shown to work. A bare timber floor on a bare slab has to be shown to pass.

Is an acoustic underlay enough?

Not on its own. An underlay is one layer of a build-up. The site result depends on the slab, the ceiling, the walls, the details at the edges and the workmanship. A maker's laboratory figure for an underlay is a different quantity from the site result.

Can Robust Details be used in a hotel?

Approved Document E describes Robust Details for new-build houses and buildings containing flats (paragraph 0.2). A room for residential purposes is tested on site. Confirm the route with the building control body.

What is the difference between ΔLw and L'nT,w?

ΔLw is a laboratory figure: how much a covering or floating floor improves impact sound insulation on a test floor. L'nT,w is the result for the finished floor on site, with the tapping machine above and the microphone below, walls included.

Who tests the floor, and when?

A test body with third-party accreditation, preferably UKAS, arranged and paid for by the person carrying out the building work. Tests are made once the rooms are essentially complete except for decoration, unfurnished, with doors closed.

Does Part E apply if I only replace the floor finish?

The Department's 2016 FAQ says the Building Regulations apply to new building work and are not retrospective. Whether a particular refit is controlled work is for the building control body. A new room for residential purposes, or a change of use, brings Part E into play. A lease may also carry its own flooring rules, which are outside this sheet.