Part E Wall & Floor Sound Reduction

Robust Details (RD) are wall and floor constructions approved and published by Robust Details Ltd (www.robustdetails.com). Notifying one removes the Regulation 41 pre-completion testing duty for the parts of the building it is notified on, and only in one situation: Approved Document E para 0.2 confines the exemption 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". It is therefore not available on a material change of use, and not available in a building of rooms for residential purposes, which Regulation 2 defines as rooms "not a dwelling-house or a flat". Annex E sets three further conditions: notify the building control body before work starts on site, quote the unique number issued by Robust Details Ltd, and build in accordance with the notified detail. A late notification puts the work back under Regulation 41. Annex E also states that 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 if measured performance did not meet the standard. Codes of the form E-WM-1 or E-WT-1 are Robust Details references and appear nowhere in Approved Document E. All of the above is the England and Wales position under Regulation 41. Scotland and Northern Ireland run their own arrangements and both accept Robust Details in some form: see the Scotland and Northern Ireland section on this page.

No, and Approved Document E offers no conversion factor to do it with. The Part E targets in Tables 1a and 1b are DnT,w + Ctr and L'nT,w, measured in the finished building and including flanking transmission through the junctions. Rw is measured on an element alone in a laboratory. AD E gives a laboratory value in one place only, Table 2, which sets Rw at least 40 dB for new INTERNAL walls and floors under Requirement E2, and it attaches no decibel rating to any separating wall or floor at all. The nearest thing in the document is Annex B paras B3.13 and B3.14, and they are not an Rw conversion: they say that 49 dB DnT,w + Ctr measured in a flanking laboratory is indicative that the same construction may achieve at least 45 dB in the field, and 58 dB L'nT,w indicative of no more than 62 dB. That is an allowance between two measurements of the SAME quantity, and para B3.11 states flatly that "It is not possible to demonstrate compliance with Requirement E1 using test results from a flanking laboratory." Compliance is shown by pre-completion testing under Regulation 41, or on a new-build house or building containing flats by notifying a Robust Detail (AD E para 0.2 and Annex E). This page carried Rw and Ln,w ranges of its own until August 2026. They were removed because no published source for them could be found, and Robust Details Ltd publishes no laboratory rating for its details either. Where a laboratory Rw is genuinely useful, take it from the tested proprietary system you are actually building, quoted by its manufacturer with the test report reference, and treat it as a comparison between products rather than evidence of compliance.

Yes. Approved Document E wall type 4.1, at para 2.147, is a double leaf frame construction with absorbent material, and it is the only framed separating wall the document specifies. Its figures: a minimum distance of 200 mm between the inside faces of the two linings; each lining two or more layers of plasterboard, each sheet at least 10 kg/m², joints staggered, each layer fixed independently to its own frame; and unfaced mineral wool batts or quilt of at least 10 kg/m³ density, at least 25 mm thick if suspended in the cavity between the frames, 50 mm if fixed to one frame, or 25 mm per batt if one is fixed to each frame. Plywood sheathing may be used in the cavity where it is needed structurally. Note the 200 mm is measured between LINING faces, not between studs, and a single stud wall is not one of the constructions in Section 2. AD E para 2.141 describes a timber frame only; for a steel framed separating wall it says to seek advice from the manufacturer, so there is no deemed-to-satisfy route for one in Approved Document E.

The impact requirement is L'nT,w no more than 62 dB for a purpose-built separating floor or stair, 64 dB for one formed by material change of use. Approved Document E meets it in one of two ways depending on the floor type, and gives figures for each. Floor type 1 uses a SOFT FLOOR COVERING, para 3.28: any resilient material, or material with a resilient base, of overall uncompressed thickness at least 4.5 mm, or any covering with a weighted reduction in impact sound pressure level of at least 17 dB. Floor type 2 uses a FLOATING FLOOR, paras 3.64 to 3.66: (a) a timber raft of at least 12 kg/m² on 45 x 45 mm battens laid loose on mineral wool of 36 kg/m³ and at least 25 mm thick; (b) a 65 mm sand cement screed, or a proprietary product of at least 80 kg/m², on that same mineral wool paper faced on the upper side, or on a resilient layer of maximum dynamic stiffness 15 MN/m³ and at least 5 mm thick under load; (c) rigid boarding above resilient or damping layers with a weighted reduction in impact sound pressure level of at least 29 dB. Floor type 3 uses a PLATFORM FLOOR, paras 3.101 and 3.102: at least two layers of board totalling 25 kg/m², each layer at least 8 mm, staggered joints, laid loose on mineral wool at least 25 mm thick and 60 to 100 kg/m³. One thing to plan for: impact tests are run WITHOUT a soft covering (para 1.10), and Annex B para B2.13 gives only two exceptions, separating floor type 1 and a concrete base whose soft covering is an integral part of the floor. On any other floor type a carpet that has been laid must be taken up for the test, or at least half the floor exposed (B2.14).