Annex D: Design details approved by Robust Details Ltd

  1. Robust details

    Robust details

    Robust Details Ltd is a non-profit distributing company, limited by guarantee, set up by the house-building industry. Its objectives are broadly to identify, arrange testing and, if satisfied, approve and publish design details that, if correctly implemented in separating structures, should achieve compliance with Requirement E1. It also carries out checks on the performance achieved in practice.

    The robust design details are available in a handbook, which may be purchased from Robust Details Ltd. The company can be contacted at: PO Box 7289, Milton Keynes, Bucks, MK14 6ZQ; telephone 0870 240 8210; fax 0870 240 8203; e-mail; website

    Although the design details are in the public domain, their use in building work is not authorised unless the builder has registered the particular use  of the relevant design detail or details with Robust Details Ltd and obtained a unique number or numbers from the company. Each unique number identifies a house or flat in which one or more of the design details are being used.

    The system of unique numbers makes possible an essential part of Robust Details Ltd’s procedures for ensuring that design details it has approved deliver reasonable sound insulation performance in practice. Robust Details Ltd carries out a programme of checks on a proportion of cases where approved design details are used.

    Under Regulation 41(4) of the Building Regulations 2010 and Regulation 20(1) of the Building (Approved Inspector, etc.) Regulations 2010, the requirement for appropriate sound insulation testing imposed by Regulations 41 and 20(1) does not apply to parts of the building which would otherwise be subject to the testing requirement where all the following apply:

    a. the building work consists of the erection of a new dwelling-house (i.e. a semi-detached or terraced house) or a building containing flats;

    b. the person carrying out the building work notifies the building control body before the start of building work on site that, in a specified part or parts of the building, he is using one or more specified design details from those approved by Robust Details Ltd. In a case where building control is being carried  out by the local authority, the notification must be given not later than the date on which notice of commencement of construction is given under Regulation 16(1) of the Building Regulations 2010;

    c. the notification specifies the unique number or numbers issued by Robust Details Ltd in respect of the specified use of the design detail or details;

    d. the building work carried out in respect of the part or parts of the building identified in the notification is in accordance with the design detail or details specified in the notification.

    If the notification is late, or if it does not specify the relevant part or parts, the design detail or details in question and the unique number or numbers, the part or parts of the building in question are subject to sound insulation testing under Regulation 41 or 20(1) and (5) in the usual way.

    If the notification is itself valid but the work is not carried out in accordance with the design detail or details, the relevant separating structures become subject to sound insulation testing under Regulation 41 or 20(1) and (5). It would be open to the builder to take remedial action such that the building control body was satisfied that the work had been brought into compliance with the specified detail or details. With that exception, testing under Regulation 41 or 20(1) and (5) would be needed on all structures that have been subject to a valid notification under Regulation 41(4) or 20(1) and (5) but which in the opinion of the building control body have not then been constructed in accordance with the specified detail or details.

    It should be noted that the compliance of work with a robust detail, in circumstances where the correct procedures have been followed to attract exemption from PCT, is not a ‘deemed to satisfy’ condition. The underlying requirement remains to achieve compliance with Part E1. The  guidance in Approved Document E is that compliance will usually be established by the measured performance of the structure. Therefore it would be open to anyone, e.g. a homeowner, who considered that a party structure does not comply with Part E1, to seek to establish that by the carrying out of tests. It would not be a defence for the builder to show that he had correctly carried out a design detail approved by Robust Details Ltd, if the structure’s measured performance were shown not to meet the performance standards in Approved Document E.