1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS 8221-2:2000 ICS 91.040
2、.01 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Code of practice for cleaning and surface repair of buildings Part 2: Surface repair of natural stones, brick and terracottaThis British Standard, having been prepared under the direction of the Sector Committee for Building
3、and Civil Engineering, was published under the authority of the Standards Committee and comes into effect on 15 April 2000 BSI 04-2000 The following BSI references relate to the work on this standard: Committee reference B/209 Draft for comment 96/18387 DC ISBN 0 580 33136 9 BS 8221-2:2000 Amendment
4、s issued since publication Amd. No. Date Comments Committees responsible for this British Standard The preparation of this British Standard was entrusted by Technical Committee B/209, General building codes, to Technical Subcommittee B/209/7, Cleaning and surface repair of buildings, upon which the
5、following bodies were represented: Chartered Institute of Building Construction Confederation Department of the Environment, Transport and the Regions Construction Directorate National Council of Building Material Producers National House-Building Council Royal Institute of British Architects Royal
6、Institution of Chartered Surveyors The following bodies were also represented in the drafting of the standard, through subcommittees and panels: Brick Development Association British Ceramic Research Ltd. Concrete Society Council for Aluminium in Building Council for the Care of Churches Department
7、of the Environment, Transport and the Regions Represented by the Building Research Establishment Ecclesiastical Architects and Surveyors Association English Heritage Historic Scotland London Transport Mortar Producers Association Limited National Grp Construction and Engineering Federation Society f
8、or Protection of Ancient Buildings Stone Federation UK Steel AssociationBS 8221-2:2000 BSI 04-2000 i Contents Page Committees responsible Inside front cover Foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Definitions 2 4 Considerations affecting surface repair decisions 3 5 Procedure
9、s associated with surface repair 4 6 Pointing and bedding mortars 6 7 Repointing 10 8 Stone masonry repair 11 9 Brickwork repair 13 10 Repair of terracotta and faience 15 11 Surface coverings 17 12 External render repairs 17 13 Treatment and protection of surfaces 17 14 Coatings 19 15 Maintenance of
10、 the exteriors of buildings 19 Annex A (informative) Non-destructive and “key-hole” survey methods 20 Annex B (informative) Use of consolidants on weathered stone and other porous materials 20 Bibliography 23 Table 1 Austenitic stainless steel grades and uses 5 Table 2 Mortar types and applications
11、7 Table 3 Mortar mixes for groups A1 to D5 7 Table 4 Non-hydraulic mortar mixes 8 Table 5 Lime mortar mixes with pozzolanic additives 8 Table 6 Classification of hydraulic limes 9ii BSI 04-2000 BS 8221-2:2000 Foreword This British Standard has been prepared by Subcommittee B/209/7. Together with Par
12、t 1, it supersedes BS 6270-1:1982 and BS 6270-2:1985, which are withdrawn. This part of BS 8221 gives guidance on surface repair of external facades of buildings. It has been prepared in parallel with BS 8221-1, which provides guidance on cleaning. This code of practice covers repointing and types o
13、f mortar, repair of stone masonry, brickwork, terracotta and faience, use of surface coverings, external render repair, and use of consolidants on weathered stone and other porous building materials. This code of practice takes the form of guidance and recommendations. It should not be quoted as if
14、it were a specification and care should be taken to ensure that claims of compliance are not misleading. WARNING This British Standard calls for the use of materials that may be injurious to health or damaging to the environment if adequate precautions are not taken. The recommendations given in thi
15、s standard refer only to technical suitability and do not absolve the user from legal obligations relating to health and safety. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compli
16、ance 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 and ii, pages 1 to 24, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates w
17、hen the document was last issued. BSI 04-2000 1 BS 8221-2:2000 Introduction This code of practice is intended to provide building owners, architects, surveyors, engineers and contractors general information concerning surface repairs of buildings. This code of practice recommends investigative proce
18、dures for selecting a suitable repair process. It describes a range of repair and conservation procedures and some problems that may be encountered. Before carrying out surface repairs, it is essential to ascertain any factors causing decay, such as open joints allowing water ingress, migrating salt
19、s from a backing wall, run-off from limestone, or a corroding metal tie/armature. 1 Scope This British Standard provides recommendations for surface repair of natural stones, clay brick, calcium silicate brick, glazed and unglazed terracotta, and faience masonry in buildings. It covers repointing an
20、d selection of mortars, and provides guidance on treatment for protection of surfaces. Surface repairs of concrete and structural repairs are not covered by this code of practice. For guidance on structural repairs, reference should be made to BS 5390 and BS 5628-1. 2 Normative references The follow
21、ing normative documents contain provisions that, through reference in this text, constitute provisions of this British Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. For undated references, the latest edition of the publication refe
22、rred to applies. BS 12:1996, Specification for Portland cement. BS 63-2:1987, Road aggregates Specification for single-sized aggregate for surface dressing. BS 187:1978, Specification for calcium silicate (sand-lime and flint-lime) bricks. BS 812-103-1, Testing aggregates Method for determination of
23、 particle size distribution Sieve tests. BS 882:1992, Specification for aggregates from natural sources for concrete. BS 890:1995, Specification for building limes. BS 1014:1975, Specification for pigments for and Portland cement products. BS 1139 (all parts), Metal scaffolding. BS 1178:1982, Specif
24、ication for milled lead sheet for building purposes. BS 1199 and 1200:1976, Specifications for building sands from natural sources. BS 1217:1986, Specification for cast stone. BS 2482:1981, Specification for timber scaffold boards. BS 2873:1969, Specification for copper and copper alloys Wire. BS 31
25、48:1980, Methods of test for water for making concrete. BS 3892-1, Pulverized-fuel ash Specification for pulverized-fuel ash for use with Portland cement. BS 3921:1985, Specification for clay bricks. BS 4551 (all parts), Methods of testing mortars, screeds and plasters. BS 4721:1981, Specification f
26、or ready-mixed building mortars. BS 4729:1990, Specification for dimensions of bricks of special shapes and sizes. BS 4887-1:1986, Mortar admixtures Specification for air-entraining (plasticizing) admixtures. BS 5224:1995, Specification for masonry cement. BS 5262:1991, Code of practice for external
27、 renderings. BS 5390:1976, Code of practice for stone masonry. BS 5628-1:1992, Code of practice for use of masonry Structural use of unreinforced masonry. BS 5628-3:1985, Code of practice for use of masonry Materials and components, design and workmanship. BS 5838-2:1980, Specification for dry packa
28、ged cementitious mixes Prepackaged mortar mixes. BS 5973:1993, Code of practice for access and working scaffolds and special scaffold structures in steel. BS 6037:1990, Code of practice for permanently installed suspended access equipment. BS 6100 (all parts), Glossary of building and civil engineer
29、ing terms. BS 6213:1982, Guide to selection of constructional sealants. BS 6431-17:1983, Ceramic floor and wall tiles Method for determination of crazing resistance Glazed tiles. BS 6477:1992, Specification for water repellents for masonry surfaces. BS 6649:1985, Specification for clay and calcium s
30、ilicate modular bricks. BS 6915:1988, Specification for design and construction of fully supported lead sheet roof and wall coverings. BS 7913:1998, Guide to the principles of the conservation of historic buildings. BS 8210:1986, Guide to building maintenance management.2 BSI 04-2000 BS 8221-2:2000
31、DD ENV 459-1:1995, Building lime Definitions, specifications and conformity criteria. BS EN 10088-2:1995, Stainless steels Technical delivery condition for sheet, plate and strip for general purposes. BS EN 10088-3:1995, Stainless steels Technical delivery conditions for semi-finished products, bars
32、, rods and sections for general purpose. BS EN ISO 3506-1:1998, Mechanical properties of corrosion resistant stainless-steel fasteners Bolts, screws and studs. BS EN ISO 3506-2:1998, Mechanical properties of corrosion resistant stainless-steel fasteners Nuts. PD 6472:1972, Guide to specifying the qu
33、ality of building mortars. Control of Pesticides Regulations, 1986. The Lead Sheet Manual A Guide to Good Building Practice. 3 Definitions For the purposes of this British Standard, the terms and definitions in BS 6100 (some of which are repeated below for convenience) and the following apply. 3.1 a
34、rmature austenitic stainless steel, copper or copper based alloy rods, wires or mesh set within a mortar repair to secure it to the parent stone and reinforce its layers 3.2 brick slip brick, either specially manufactured or cut, of the same height and length as a header or a stretcher, and usually
35、with a thickness of between 20 mm and 50 mm 3.3 conservation stabilizing and preventing or retarding further deterioration of masonry 3.4 crazing fine, hair-line stress relief cracks caused by inability of a glazed surface and the underbody to accommodate thermal and moisture movement NOTE Crazing i
36、s also known as poor glaze fit. 3.5 cramp shaped piece of metal or slate, bedded into sinkings in stone units to tie them to each other or to their backing 3.6 Coade stone proprietary off-white terracotta body produced from a kaolinitic clay, containing titanium dioxide, feldspar as flux and quartz
37、as glass-forming agent, and a grog of powdered prefired clay NOTE Coade stone was manufactured by the Coade family between 1769 and 1820. 3.7 dowel short piece of material sunk or cast into adjacent hidden wall faces, to align or prevent movement of the faces 3.8 engobe surface application by brush
38、or spray of liquid clay, before firing, to provide an opaque, unglazed coloured finish on some forms of terracotta 3.9 faience masonry, similar to terracotta, with one or more surfaces covered with a clear or coloured glaze 3.10 fired-clay unit masonry unit formed from brick-earth, clay or shale, dr
39、ied and burned NOTE Fired-clay should not be confused with fireclay, which is used for making refractory bricks. 3.11 fireskin thin, smooth, outer layer on unglazed terracotta, containing a high proportion of fines NOTE In traditional firing processes, fireskin is vitrified to a greater degree than
40、the body of clay beneath. Fireskin has a protective role and retention of it should be a priority in cleaning and repair works. 3.12 gauged brickwork soft bricks cut to shape and abraded to the size required 3.13 glaze mixed paste of fluxes and colouring ingredients that becomes a thin, vitreous, tr
41、ansparent or coloured surface finish of glassy, opaque or translucent consistency on firing NOTE Glazes can be plain, mottled or textured and can range from high-gloss to egg-shell finish. BSI 04-2000 3 BS 8221-2:2000 3.14 grog inert filler added to a clay mixture before firing to control shrinkage
42、3.15 grout flowing material that sets after application, used to fill fissures and cavities 3.16 hydraulic lime binder of limestone, clay, and calcium and magnesium carbonates, that sets and hardens by chemical interaction with water, both in water and in air NOTE Hydraulic limes are classified as e
43、minently, moderately or feebly hydraulic limes. 3.17 non-hydraulic lime binder consisting mainly of calcium hydroxide (high calcium lime) or magnesium carbonate (magnesian/dolomitic lime) that, when mixed with water, sets slowly by drying out and atmospheric carbonation NOTE Non-hydraulic limes can
44、be prepared and used as a putty or as a powder (hydrated lime). 3.18 piecing-in cutting out a decayed or damaged section of masonry and inserting new NOTE Piecing in is also known as indenting. 3.19 slip casting method of manufacture of thin solid slabs, hollow blocks, or tiles, in which a suspensio
45、n of clay particles in water, of liquid, creamy consistency, is poured into plaster moulds and allowed to dry solid before releasing, drying and firing 3.20 surface repair renewal, by minor replacement, of damaged or heavily weathered masonry surfaces with similar or compatible material 3.21 terraco
46、tta fired clay, fine textured and unglazed, usually yellow to brownish-red 4 Considerations affecting surface repair decisions 4.1 General COMMENTARY Most surface repairs are concerned with prevention of moisture ingress or repair/replacement of decayed or damaged elements. Work to improve the weath
47、er resistance of buildings may relate to repair of surface defects likely to have a long-term detrimental effect on the whole or part of the structure, replacement of defective fixings, or reinstatement of the surface of a building after structural repairs. Work to improve the appearance of building
48、s may include repairs of decayed or damaged mouldings, surface decoration or sculpture, badly stained areas, and areas that have been badly repaired in the past. Repair work has many criteria to consider, including method of repair, materials of construction, and the condition of these. Previous exp
49、erience with a building or similar buildings may be useful but should not be assumed to apply fully. Distinction should be made between what is necessary and what is desirable before carrying out surface repair work. If funds are limited or if the building is of architectural or historic value, only essential repairs should be carried out. Ease of access for future work, relative costs of hiring/erecting scaffolding and the probable frequency of maintenance, should be considered at the planning stage of repairs. If significant numbe
