BS 8215-1991 Code of practice for design and installation of damp-proof courses in masonry construction《砖石砌筑工程施工的防潮层的设计和安装的实用规程》.pdf

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1、BRITISH STANDARD BS 8215:1991 Code of practice for Design and installation of damp-proof courses in masonry constructionBS8215:1991 This British Standard, having been prepared under the directionof the Elements and Components (of Diverse Materials)for Buildings Standards Policy Committee, waspublish

2、ed under the authorityof the Board of BSI andcomes into effect on 28February 1991 BSI 02-1999 The following BSI references relate to the work on this standard: Committee reference ECB/44 Draft for comment 84/14417 DC ISBN 0 580 18849 3 Committees responsible for this British Standard The preparation

3、 of this British Standard was entrusted by the Elements and Components (of Diverse Materials) for Buildings Standards Policy Committee (ECB/-) to Technical Committee ECB/44, upon which the following bodies were represented: Associated Lead Manufacturers Limited Association of British Roofing Felt Ma

4、nufacturers Association of Jute Spinners and Manufacturers Autoclaved Aerated Concrete Products Association Brick Development Association British Board of Agrement British Ceramic Research Ltd. Consumer Policy Committee of BSI Contract Flooring Association Copper Development Association Department o

5、f the Environment (Building Research Establishment) Department of the Environment (Property Services Agency) Institute of Building Control Institute of Clerks of Works of Great Britain Inc. Lead Sheet Association Local Authority Organizations Mastic Asphalt Council and Employers Federation Natural S

6、late Quarries Association Packaging and Industrial Films Association Royal Institute of British Architects Royal Institution of Chartered Surveyors Society of Chemical Industry Amendments issued since publication Amd. No. Date CommentsBS8215:1991 BSI 02-1999 i Contents Page Committees responsible In

7、side front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Basic principles 1 4 Materials 1 5 Design 1 6 Sitework 9 Figure 1 Examples of positions where DPCs may be required 2 Figure 2 Position of DPC above ground level 3 Figure 3 DPC beneath jointed copings 4 Figure 4 DPC in a parapet wall 4 Figure 5

8、 DPCs in masonry chimney at roof penetration 4 Figure 6 Principles of cavity tray design 5 Figure 7 Sealed stop-ends to a cavity tray 5 Figure 8 Co-ordination of DPCs around an opening in a cavity wall (diagrammatic representation of basic principles) 6 Figure 9 Stepped cavity trays 7 Figure 10 DPC

9、in a cavity parapet wall 8 Figure 11 DPCs at junction in concrete frame 10 Figure 12 Continuity of DPC 10 Figure 13 Detail of DPC overlap 11 Figure 14 Installation of a flexible DPC 11 Figure 15 Cavity tray with stop-ends 12 Figure 16 Cavity tray across piers 13 Figure 17 Formation of internal and e

10、xternal corners 13 Table 1 British Standards for DPC materials 3 Table 2 Structural considerations affecting the selection of DPCs 9 Table 3 Joints in DPCs 10 Publications referred to Inside back coverBS8215:1991 ii BSI 02-1999 Foreword This British Standard has been prepared under the direction of

11、the Elements and Components (of Diverse Materials) for Buildings Standards Policy Committee. It supersedes the information contained in Appendix C ofBS 743 which is deleted by amendment. It also supersedes clause 10 of section 3 of CP102: section 1 and section 2 of CP102 and CP102 have already been

12、superseded by BS8102 and the remaining text of CP102 is to be amended. This British Standard is intended as a guide to the design and installation of damp-proof courses in masonry constructions covered by BS 5628 which gives general recommendations for the design and construction of brick and block

13、masonry, including materials and components. In BS 5628-1 the following recommendation is given: Designers should pay particular attention to the characteristics of the materials chosen for damp-proof courses. Materials which squeeze out are undesirable in highly stressed walls, and the effect of sl

14、iding at the damp-proof course should be considered especially in relation to lateral loading. In general, advice on the resistance to compression, tension, sliding and shear should be sought from the manufacturers of the damp-proof course. Many of the basic principles in this standard are relevant

15、to other forms of construction. In drafting this standard it has been assumed that the design will be undertaken by appropriately qualified and experienced designers having regard to the recommendations and calculation methods contained in BS 5628 and that construction will be carried out by trained

16、 operatives under the direction of qualified supervisors. BSI has published draft methods of test for flexural bond strength and short term shear strength and creep deformation of damp-proof courses. These drafts (DD86-1 and DD 86-2) aim to provide basic data for future performance specifications fo

17、r damp-proof course materials. A further document, DD 86-3 describes characteristic strengths of damp-proof course materials used in conjunction with designated mortars. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsi

18、ble 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 and ii, pages1to 14, an inside back cover and a back cover. This standard has been u

19、pdated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.BS8215:1991 BSI 02-1999 1 1 Scope This British Standard contains recommendations for the selection, design and installation of damp-proof courses (DPCs) in bot

20、h solid and cavity masonry constructions: it does not cover the waterproofing of underground structures, such as basements, where water is under hydrostatic pressure (see BS 8102). This standard does not deal with the installation of chemical DPCs (seeBS6576) nor with the control of condensation (se

21、eBS 5250) nor with the surface treatment of masonry with water repellents (see BS 6477). Guidance on basic principles concerning DPCs, their function and their installation in masonry is given in clause 3. NOTEThe titles of publications referred to in this standard are listed on the inside back cove

22、r. 2 Definitions For the purposes of this British Standard the definitions given in BS 6100-5 apply. 3 Basic principles Water is the prime cause of deterioration in building materials and constructions and the presence of moisture encourages growth of mould which is injurious to health. Building Reg

23、ulations, framed to protect the safety, health and welfare of building occupants, require that buildings be designed to be stable and to ensure that water neither damages the building fabric nor penetrates to the interior where it may constitute a health hazard to occupants. Ground water can penetra

24、te building fabric from below, rising vertically by capillary action. Water falling vertically as rain, hail and snow is under a slight head of pressure. It can also, under the influence of the wind, travel obliquely, horizontally, and even vertically upwards. Residual water also comes under the inf

25、luence of gravity and thus exerts pressure. Figure 1 illustrates typical positions in which DPCs may be required: BS 5628-3 should be consulted for further advice. The function of a DPC is to prevent moisture or water passing from one part of a construction to another. DPCs should be designed in con

26、junction with flashings and damp-proof membranes to ensure a continuous barrier. Not only should they form a barrier to the passage of water but they should also deflect such water to the exterior of the building where it can safely drain away. DPCs should be installed with care. The constructions i

27、n which they are installed should have sufficient stability to preclude settlement or lateral movement which may impair the performance of the DPC. The necessary inclusion of a DPC in masonry construction may materially affect overall structural performance by introducing a plane of weakness. The ov

28、erall stability of the structure should be considered in relation to the loads imposed upon it by the weight of the construction and by external forces such as wind pressures, thermal and moisture movements (seeBS 5628-1 and BS 5628-3). 4 Materials The materials that should be used to form DPCs in m

29、asonry fall into three groups: a) flexible materials, such as sheet lead, sheet copper, bitumen DPC, bitumen/sheet metal composites, polyethylene, bitumen polymer, pitch polymer; b) semi-rigid materials, such as mastic asphalt; c) rigid materials, such as dense bricks and slates, bedded in cement mo

30、rtar. DPC materials should comply with the British Standards listed in Table 1. Other materials may also prove suitable for forming DPCs: the specifier should satisfy himself that they have been properly evaluated and found suitable for such use. See clause 5 for information on the selection of DPC

31、materials. 5 Design 5.1 Exposure conditions The designer should first determine the degree of exposure, the risk of penetration from any direction (upwards, downwards or horizontally) and the consequences of water penetration. NOTEDPCs need not be provided where they are not necessary, e.g. above a

32、suitably designed impervious lintel, beneath an impervious sill or continuous coping, or across openings protected by overhanging eaves. 5.2 Primary protection Careful design, including the provision of weathered copings, sills, overhangs and projections, should provide primary protection which will

33、 eliminate or greatly reduce the risk of damage to building fabric and help to prevent water penetration to the interior of the building.BS8215:1991 2 BSI 02-1999 5.3 Integrated design of DPCs DPCs should be designed in conjunction with membranes and flashings to form a complete system of protection

34、 impervious to moisture. NOTEThe preparation of three-dimensional drawings helps to focus attention on critical details and on those junctions which require lapping or sealing: it also identifies areas where it may be advantageous to use prefabricated components. Figure 1 Examples of positions where

35、 DPCs may be requiredBS8215:1991 BSI 02-1999 3 Table 1 British Standards for DPC materials 5.4 Location of DPCs A DPC should be installed in every external wall immediately above ground level to prevent moisture from the ground being drawn up by capillary attraction; in order to guard against rainwa

36、ter bouncing off the ground and splashing the wall, the DPC should be set not less than 150mm above the surrounding finished levels adjacent to the wall. NOTEOn sloping sites the DPC may need to be stepped (seeFigure 2). A DPC should be installed beneath sills and copings which are formed with joint

37、ed units, e.g.pre-cast concrete or bricks, in order to protect the wall beneath against water penetrating the joints (seeFigure 3). A DPC should be incorporated in a parapet wall or abutment to provide continuity of protection with the roof covering. It should be positioned not less than 150mm above

38、 the roof finish and be set on top of a cover flashing to the roof upstand (see Figure 4). Where a masonry chimney penetrates a flat or pitched roof or abutment, a DPC should be installed in order to protect the masonry within the building against water soaking down from above (seeFigure 5). Number

39、of British Standard Title Group or class of material BS 1178 Specification for milled lead sheet for building purposes Code 4 BS 2870 Specification for rolled copper and copper alloys: sheet, strip and foil C 104 or C 106 in the annealed condition (grade 0) BS 6398 Specification for bitumen damp-pro

40、of courses for masonry A, B, C, D, E or F BS 6515 Specification for polyethylene damp-proof courses for masonry Minimum thickness 0.46mm BS 6577 Specification for mastic asphalt for building (natural rock asphalt aggregate) T1418 BS 6925 Specification for mastic asphalt for building and civil engine

41、ering (limestone aggregate) T1097 BS 3921 Specification for clay bricks DPC1 or DPC2 BS 743 Specification for materials for damp-proof courses (clause 7. Slates) Type B Figure 2 Position of DPC above groundlevelBS8215:1991 4 BSI 02-1999 Figure 3 DPC beneath jointed copings Figure 4 DPC in a parapet

42、wall Figure 5 DPCs in masonry chimney at roof penetrationBS8215:1991 BSI 02-1999 5 5.5 DPCs in cavity walling DPCs in cavity walls should be designed with particular care. NOTEBS 5628-3 advises that some water will inevitably penetrate the outer masonry leaf of a cavity wall during prolonged periods

43、 of wind-driven rain. It should be assumed that rainwater will run down the inner surface of the outer leaf. Openings in, penetrations through and abutments to a cavity wall should be protected by integrated horizontal and vertical DPCs designed to deflect water away from the inner leaf and allow it

44、 to discharge via weepholes. Forming an effective barrier to damp in cavity walls may give rise to complex three-dimensional details which, it is recommended, are prefabricated. Horizontal DPCs which bridge a cavity should be stepped up by not less than 150mm from the outer to the inner leaf. Such D

45、PCs, known as cavity trays, should preferably be formed in one piece; any necessary joints should be fully supported, well lapped and sealed (see Figure 6). Particular care should be taken in forming changes of direction in cavity trays. There is a risk of water running off the ends of a discontinuo

46、us cavity tray and running back into the construction: a discontinuous cavity tray should be fitted with sealed stop-ends (see Figure 7). Vertical DPCs should be provided at the jambs of openings in cavity walls: they should be designed to lap under any cavity tray across the head of the opening and

47、 to lap over any DPC at sill level so as to discharge water out of the wall (seeFigure 8). Where a cavity wall is partially internal and partially external, protection should be provided to prevent water in the cavity reaching the wall within the building at a lower level. At pitched roof abutments

48、a carefully detailed series of cavity trays, all with stop-ends, or proprietary prefabricated cavity trays as illustrated in Figure 9 should be used. Figure 6 Principles of cavity tray design Figure 7 Sealed stop-ends to a cavity trayBS8215:1991 6 BSI 02-1999 Figure 8 Co-ordination of DPCs around an

49、 opening in a cavity wall (diagrammatic representation of basic principles)BS 8215:1991 BSI 02-1999 7 Figure 9 Stepped cavity traysBS8215:1991 8 BSI 02-1999 Where a cavity wall forms a parapet extending more than 150mm above a roof it is likely to be exposed to rainwater on both sides: a cavity tray which will deflect water away from the inner leaf and allow it to drain out without by-passing the roof covering should then be incorporated (see Figure 10). 5.6 Selection of DPC material Not all materials are equall