《BS-5262-1991.pdf》由会员分享，可在线阅读，更多相关《BS-5262-1991.pdf（46页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 5262:1991 Code of practice for External renderings Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 This British Standard, having been prepared under the direction of the Elements and Components (of Diverse Ma
2、terials) for Buildings Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 October 1991 BSI 01-1999 First published, as CP 221, January 1960 Second edition, as BS 5262, February 1976 Third edition, October 1991 The following BSI references
3、 relate to the work on this standard: Committee reference ECB/5 Draft for comment 89/14492 DC ISBN 0 580 19747 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Elements and Components (of Diverse Materials) for Buildings Standards Polic
4、y Committee (ECB/-) to Technical Committee ECB/5, upon which the following bodies were represented: Aggregate Concrete Block Association Association of Lightweight Aggregate Manufacturers British Aggregate Construction Materials Industries Building Employers Confederation Chartered Institute of Buil
5、ding Concrete Society Contract Flooring Association Department of the Environment (Property Services Agency) Department of the Environment (Building Research Establishment) Federation of Association of Specialists and Sub-Contractors Federation of Plastering and Drywall Contractors Institution of St
6、ructural Engineers Mastic Asphalt Council and Employers Federation Mortar Producers Association Limited National Federation of Terrazzo Mosaic Specialists Royal Institute of British Architects Sand and Gravel Association Limited Scottish Master Plasterers Association Society of Chemical Industry The
7、 following bodies were also represented in the drafting of the standard, through subcommittees and panels: Autoclaved Aerated Concrete Products Association External Wall Insulation Association National House-Building Council Amendments issued since publication Amd. No.DateComments Licensed Copy: she
8、ffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 BSI 01-1999i Contents Page Committees responsibleInside front cover Forewordv Section 1. General 1Scope1 2Definitions1 3Exchange of information1 4Building programme1 Section 2. Materials 5Cements2 6
9、Limes2 7Aggregates2 7.1Sands2 7.2Coarse aggregate2 7.3Artificial aggregates2 8Pigments2 9Fibres2 10Admixtures2 10.1 General2 10.2 Plasticizers2 10.3 Waterproofers2 10.4 Water-retentive agents2 10.5 Polymer dispersions2 11Bonding agents3 12Water3 13Ready-mixed rendering materials3 13.1 Ready-mixed li
10、me : sand3 13.2 Retarded ready-to-use cement : lime : sand or cement : sand3 13.3 Bagged rendering materials3 13.4 Proprietary materials3 14Reinforcement, metal lathing and beads3 14.1 General3 14.2 Expanded metal3 14.3 Ribbed lathing3 14.4 Welded wire mesh3 14.5 Non-metallic mesh3 14.6 Beads and st
11、ops3 15Fixings3 15.1 General3 15.2 Nails and pins4 15.3 Staples4 15.4 Screws and bolt fixings4 15.5 Washers and ancillary angles, brackets or cleats4 15.6 Wire4 15.7 Fixing blocks in solid backgrounds4 15.8 Plugs4 16Firring4 Section 3. Design 17Factors influencing the design of the rendering system5
12、 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 ii BSI 01-1999 Page 17.1 Choice of rendering mixes5 17.2 Provision of joints5 17.3 Preparation of background5 17.4 Detailing of architectural features5 18Conditions of exposure5 1
13、9Resistance to rain penetration5 20Soluble salts in background9 21Effects of atmospheric pollution9 22Corrosion of metals10 23Effects of freezing10 24Thermal properties10 25Durability10 25.1 General10 25.2 The background, its nature and durability10 25.3 Type of rendering10 25.4 The method of applic
14、ation, particularly in relation to the nature of the background10 26Fire resistance and combustibility11 27Resistance to cracking11 27.1 Movements of the structural background11 27.2 Movement of the rendering11 27.3 Crack control11 28Resistance to crazing12 29Protection afforded by architectural fea
15、tures12 29.1 General12 29.2 Parapet and screen walls12 29.3 Eaves and verges13 29.4 String courses and similar features13 29.5 Sills13 29.6 Soffits and reveals13 29.7 Treatment at base of walls14 30Rendering to chimney stacks14 31Mixes16 31.1 General16 31.2 Designation I mixes16 31.3 Designations II
16、, III and IV mixes16 31.4 Designation V mixes16 31.5 Spatterdash mixes16 31.6 Machine- and trowel-applied decorative finishes16 31.7 Mixes containing polymer dispersions16 31.8 Mixes containing fibres16 31.9 Special mixes for external insulation17 32Number and thickness of coats17 32.1 General17 32.
17、2 Spatterdash, stipple and adhesive slurry17 32.3 Dubbing-out17 32.4 Undercoats17 32.5 Final coat17 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 BSI 01-1999iii Page 33Types of finish17 33.1 General17 33.2 Trowel finishes17 33
18、.3 Thrown finishes18 34Colour and texture18 34.1 General18 34.2 Solar radiation18 35Ornamentation in relief18 35.1 General18 35.2 Moulding and modelling19 35.3 Sgraffito19 Section 4. Backgrounds 36Characteristics22 36.1 General22 36.2 Strength22 36.3 Suction22 36.4 Key22 36.5 Joints and cracks22 36.
19、6 Durability22 37Types22 38Preparation of background24 38.1 General24 38.2 Preparatory treatments25 38.3 Brickwork25 38.4 Blockwork25 38.5 Concrete25 38.6 Insulation boards26 38.7 Reinforcement26 Section 5. Work on site 39Storage of materials28 39.1 Lime, cement and pre-mixed dry bagged materials28
20、39.2 Ready-mixed lime : sand for mortar28 39.3 Ready-to-use cement : lime : sand or cement : sand28 39.4 Aggregates28 39.5 Metal lathing and firring battens28 40Scaffolding28 41Cleanliness and protection of adjacent work28 42Proportioning28 43Mixing29 43.1 General29 43.2 Preparing mixes of cement :
21、lime : sand29 43.3 Preparing mixes of cement and sand used with plasticizers29 43.4 Preparing mixes of masonry cement and sand29 43.5 Preparing mixes containing fibres29 44Forming architectural features29 45Application of the various coats29 45.1 General29 45.2 Curing29 Licensed Copy: sheffieldun sh
22、effieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 iv BSI 01-1999 Page 45.3 First undercoat30 45.4 Subsequent undercoat30 45.5 Final coat30 46Machine-applied renderings31 47Polymer-modified cement-based renderings31 Section 6. Maintenance and repair 48General3
23、2 49Inspection32 50Repairs to cracks32 50.1 General32 50.2 Rendered finishes only32 50.3 Rendering and background32 50.4 Making good to rendering32 51Repair of hollow or detached areas33 51.1 General33 51.2 Rendered finish only33 51.3 Spalled backgrounds33 52Overcoming unsatisfactory appearance33 52
24、.1 General33 52.2 Cleaning33 52.3 Paint treatment33 52.4 Further rendering coats33 53Overcoming water penetration34 53.1 General34 53.2 Colourless treatments34 53.3 Paint treatments34 54Repairs to painted rendering or stucco34 Appendix A Inspection of defective renderings35 Figure 1 Fixings installe
25、d in wall before rendering6 Figure 2 Annual driving-rain index: British Isles7 Figure 3 Annual relative driving-rain index for each of eight wind directions at 20 stations8 Figure 4 Movement joints in rendering aligned to movement joints in background12 Figure 5 Elevation showing possible position o
26、f movement joints in rendering on metal lathing13 Figure 6 Parapet and string course details14 Figure 7 Types of sill15 Figure 8 Alternative details at base of walls16 Figure 9 Illustration of rendering defects35 Table 1 Mixes suitable for rendering20 Table 2 Severe exposure: recommended rendering s
27、pecifications20 Table 3 Moderate and sheltered exposure: recommended rendering specifications21 Table 4 Summary of precautions for rendering on to various types of new backgrounds23 Table 5 Summary of recommendations for rendering on to contaminated or deteriorated existing backgrounds24 Publication
28、(s) referred to36 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 BSI 01-1999v Foreword This British Standard has been prepared under the direction of the Elements and Components (of Diverse Materials) for Buildings Standards Po
29、licy Committee. It is a revision of BS 5262:1976, which is withdrawn. The standard gives recommendations for building details, design and materials considerations, the selection of mixes and the application of cement-based external renderings. A rendered finish may be applied to a variety of backgro
30、unds, either to improve resistance to rain penetration and weathering or for aesthetic reasons. In this edition of BS 5262, account has been taken of recent investigations into rendering failures. Recommendations for polymer-modified renderings and rendering over external insulation have been includ
31、ed. It has been assumed in the drafting of this standard that the application of its provisions is entrusted to appropriately qualified and experienced people, for whose guidance it has been prepared. A British Standard does not purport to include all the necessary provisions of a contract. Users of
32、 British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to vi, pages 1 to 36, an inside back cover and a back
33、 cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI vi blank Licensed
34、Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 BSI 01-19991 Section 1. General 1 Scope This code of practice gives recommendations for cement-based external renderings on all common types of background. It includes renderings on both ne
35、w and old backgrounds and the maintenance and repair of existing work. Renderings for liquid retaining structures such as tanks and manholes and renderings applied as a background for any form of cladding are not included. NOTE 1For renderings to receive external tiling and mosaics, see BS 5385-2. N
36、OTE 2The titles of the publications referred to in this standard are listed on page 36. 2 Definitions For the purposes of this British Standard, the definitions given in BS 6100-6 apply. 3 Exchange of information The working drawings and specifications should be prepared in sufficient detail to affo
37、rd proper guidance in the execution of the work. When preparing rendering details the designer should take into account the following points. a) The choice of type of rendering to be used depends on the functional requirements, the nature and conditions of exposure of the background and the aestheti
38、c requirements. The nature of the background may dictate the type of rendering finish that can be applied and, therefore, the background and rendering system should be considered together. b) The area and types of finish and thickness required together with sufficient details of the surfaces to be r
39、endered, architectural features such as string courses, sills, positions of damp-proof courses, etc., to enable the most suitable rendering materials and methods to be selected. c) The possibility of a bonding treatment being required to ensure good adhesion between the rendering and the background.
40、 d) The likelihood of inclement weather (see 45.1). e) The type of scaffolding to be used and items in need of protection (see clauses 40 and 41). f) The method of curing required. (See 45.2.) There should be an exchange of information between those responsible for the constructional work, the rende
41、ring and any subsequent work, and with other trades whose work will affect or be affected by the rendering, as soon as possible after acceptance of contract. At a reasonable time prior to work commencing, all necessary working drawings should be provided and the site should be visited to monitor bui
42、lding progress. Arrangements should then be made for any necessary preparatory work to be carried out without causing delay to work that is to follow. 4 Building programme The programme planned for any building work should include external rendering, if applicable. Where possible, the programme shou
43、ld be agreed in consultation with those who will become responsible for carrying out the work. When considering the programme for machine-applied rendering, it should be remembered that mechanical methods of application can cover larger areas in shorter periods than traditional methods and therefore
44、 a greater area should be made available within the programme to allow for this. In preparing the programme, each operation should be considered in relation to the others, and due consideration should be given to the economical use of construction plant, equipment and scaffolding by all trades. Cons
45、ideration should also be given in the programme to ensuring that the various trades follow one another in a correct sequence and do not interfere unduly with each others work. The programme should be carefully planned to avoid risk of serious damage or difficulties occasioned to or by other trades.
46、The programme should allot times for the construction and preparation of the backgrounds to receive renderings and allow sufficient intervals for drying out and shrinkage of the background to take place. The programme should include times for commencement of rendering and allow for sufficient time b
47、etween coats for drying out and shrinkage to take place. Due regard should also be given to any special requirements for finishing coats which are usually applied downwards starting from the top. A detailed programme for the work, prepared in consultation with those responsible for the general build
48、ing contract, should be maintained. Arrangements should be made and time allowed for regular site inspections to enable any defects to be located and remedied, and for drying out and maturing of such repairs at the correct stages as the work proceeds. The date when each area is rendered should be re
49、corded. Records should also include critical dates concerning the building construction, weather conditions and the preparation of backgrounds for rendering. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 16:10:42 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5262:1991 2 BSI 01-1999 Section 2. Materials 5 Cements Cement should comply with one of the following British Standards BS 12; BS 146; BS 4027; BS 5224. 6 Limes Building limes should comply with BS 890. 7 Aggregates 7.1 Sands The quality of sands, especially for final coats, should