Section 3 Wall cladding

Wall cladding

  1. General
    1. Technical approach
      1. Loading
        1. Fixings
          1. Further guidance

            General

            3.1 Wall cladding presents a hazard if it becomes detached from the building. This section provides guidance on the support and fixing of wall cladding. An acceptable level of safety can be achieved by different means depending on the type and location of the cladding. The guidance given relates to all forms of cladding, including curtain walling and glass facades. It is not intended to provide guidance concerning the weather resistance of wall cladding which is included in Approved Document C, Site preparation and resistance to moisture, or guidance on resistance to spread of fire which is included in Approved Document B, Fire safety, or guidance in relation to sound insulation, which is included in Approved Document E, Resistance to the passage of sound.

            Technical approach

            3.2 The cladding will meet the safety requirement if:

            • A: the cladding is capable of safely sustaining and transmitting to the supporting structure of the building all dead, imposed and wind loads, and
            • B: the cladding is securely fixed to and supported by the structure of the building. This shall comprise both vertical support and horizontal restraint, and
            • C: provision is made, where necessary, to accommodate differential movement of the cladding and the supporting structure of the building, and
            • D: the cladding and its fixings (including any support components) are of durable materials; the design life of the fixings being not less than that of the cladding. Fixings shall be corrosion resistant and of a material type appropriate for the local environment.

             

            Loading

            3.3 Wind loading on the cladding should be derived from BS EN 1991-1-4:2005 with its UK National Annex with due consideration given to local increases in wind suction arising from funnelling of the wind through gaps between

            3.4 Where the cladding is required to support other fixtures, e.g. handrails, and fittings, e.g. antennae and signboards, account should be taken of the loads and forces arising from such fixtures and fittings.

            3.5 Where the wall cladding is required to function as pedestrian guarding to stairs, ramps, vertical drops of 600mm or greater or as a vehicle barrier, then account should be taken of the additional imposed loading, as stipulated in Approved Document K, Protection from falling, collision and impact.

            3.6 Where the wall cladding is required to safely withstand lateral pressures from crowds, an appropriate design loading is given in BS EN 1991-1-1:2002 with its UK National Annex and the Guide to Safety at Sports Grounds (4th Edition, 1997).

            Fixings

            3.7 The selection of fixings for supporting cladding should be determined from a consideration of the proven performance of the fixing and the risks associated with the particular application. In this regard applications should be designated as being either non-redundant (where the failure of a single fixing could lead to the detachment of the cladding) or redundant (where failure or excessive movement of one fixing results in load sharing by adjacent fixings) and the required reliability of the fixing determined accordingly.

            Notes:Attention is drawn to the availability of anchors with an ETA (European Technical Approval) gained in accordance with the requirements of ETAG 001 Guideline for European Technical Approval Metal Anchors for use in Concrete Parts 1-5, which cover both redundant and non-redundant applications, and Part 6 which covers ‘Anchors for multiple use in non-structural applications’ and which can effectively be regarded as covering redundant use. The UK definition of ‘multiple use’ is contained in an annexe to the ETAG Part 6 and is framed in such a way that all applications can be validated as to whether or not they conform to this category without calculation. All ETAG parts may be downloaded in English from www.eota.be.

            3.8 The strength of fixings should be derived from tests using materials representative of the material into which the fixing is to be anchored, taking account of any inherent weaknesses that may affect the strength of the fixing, e.g. cracks in concrete due to shrinkage and flexure, or voids in masonry construction. The design loads will generally be available from the manufacturer’s test data determined from a European Technical Approval (ETA) or an extant British Standard.

            Note: ETAs are available which cover use either in both cracked and non-cracked concrete or in non-cracked concrete only. Those which cover both cracked and non-cracked concrete allow higher loads for use in non-cracked than in cracked concrete.

            Further guidance

            3.9 The use of large panels of glass in cladding of walls and roofs where the cladding is not divided into small areas by load-bearing framing requires special consideration. Guidance is given in the following documents:

            The Institution of Structural Engineers’ Report on ‘Structural use of glass in buildings’ dated 1999, available from 11 Upper Belgrave Street, London SW1X 8BH.

            ‘Nickel sulfide in toughened glass’ published by the Centre for Window Cladding and Technology dated 2000.

            3.10 Further guidance on cladding is given in the following documents:

            The Institution of Structural Engineers’ Report on ‘Aspects of Cladding’ dated 1995.

            The Institution of Structural Engineers’ Report on ‘Guide to the structural use of adhesives’ dated 1999.

            BS 8297:2000 Code of practice for the design and installation of non-load-bearing pre-cast concrete cladding.

            BS 8298:2010 Code of practice for the design and installation of natural stone cladding and lining.

            3.11 Additional guidance on fixings is given in the following documents:

            • ETAG No. 001 1997 Guideline for EuropeanTechnical Approvals of Metal Anchors for use in Concrete, European Organisation for Technical Approvals (EOTA), Brussels. All EOTA parts maybe downloaded in English from www.eota.be.
            • Part 1 Anchors in general.
            • Part 2 Torque controlled anchors.
            • Part 3 Undercut anchors.
            • Part 4 Deformation controlled anchors. Part 5 Bonded anchors.
            • Part 6 Metal anchors for redundant use in concrete for lightweight systems.
            • BS 5080-1:1993 Structural fixings in concrete and masonry. Method of test for tensile loading.
            • CIRIA Report RP 566 Cladding Fixings: Good practice guidance, available from 6 Storey’s Gate, London SWIP 3AU.
            • CIRIA Reports C579 and C589 Retention of masonry facades – Best practice guide.
            • Guidance notes published by the Construction Fixings Association, www.fixingscfa.co.uk.
            • Guidance Note: Procedure for Site Testing Construction Fixings (1994).
            • Guidance Note: European Technical Approvals for Construction Fixings (1998).
            • Guidance Note: Anchor Selection (1995).
            • Guidance Note: Fixings and Fire (1998).
            • Guidance Note: Anchor Installation (1996).
            • Guidance Note: Bonded Anchors (1999).
            • Guidance Note: Heavy Duty Expansion Anchors (1997).
            • Guidance Note: Fixings for Brickwork and Blockwork (1997).
            • Guidance Note: Undercut Anchors (1998).
            • Guidance Note: Fixings and Corrosion (2002).