SANS 10120-3 HB-1985 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 3 Guidance for design Section HB Cladd.pdf

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1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. SABS 0120 : Part 3 Section HB-1985 Cladding and sheeting Clause PART 3 t GUIDANCE FOR DESIGN SECTION HB CONTENTS Page Number PRE-TENDER CONSIDERITIONS .

4、Investigations Peak wind loads . Administration . Essential procedure before issue of letter of acceptance of tender Period of validity of tenders Approval of data given by tenderer on detail sheets . Tenderers and approved manufacturers Documentation . Provision for escalation . Detail sheets and s

5、pecial conditions of tender Project specification Inhibiting wet-storage stain on galvanized sheeting . Flashinqs to protrusions Site handling of aluminium sheeting Detail sheet . DESIGN REQUIREMENTS General Design and Selection of Fasteners Peak Wind Loads Detailed Instructions Flashinqs Factory gu

6、tters . Flashings to protrusions Gutters. Launders and Downpipes . APPLICABILITY OF OTHER CODES TEST PROCEDURES QUALITY CONTROL AND OTHER CONSIDERATIONS Failures due to Wind Loading February 1985 Approved by the COUNCIL OF THE SOUTH AFRICAN BIJREAU OF STANDARDS SABS 0120 : Part 3 Section HB-1985 Cla

7、dding and sheeting SABS 1200 Ill3 : CLADDING AND SHEETING NOTE: The clause nunrber(s) given at the beginning or after the heading of a clause is/are. unless otherwise stated, the number(s) of the relevant clause(s) of SABS 1200 HE. PRETENDER CONSIDERATIONS INVESTIGATJONS Peak Wind Loads, Determine t

8、he peak wind loads expected for the region in which the site is located. (See 5.1 below and Subclause 3.2.l(d) of Section HB of Part 2 of the code.) ADMINISTRATION Essential Procedure before lssue of Letter of Acceptance of Tender. Do not, on behalf of the employer, sign (or arrange for the employer

9、 to sign) the letter of acceptance of the tender until the action required in terms of 1.2.3 below and, when applicable, in terms of Subclauses 7.1.1 and 7.1.4 of SABS l200 HR has been finalized. This precaution is necessary because the contractors written completion of the tender together with a le

10、tter of acceptance from the employer constitutes a legally binding contract (see Subclause 1.3.2 of Section A of Part 3 of the code and The law of buildin contracts and arbitration in South frical). Should the prospective contractor propose a variation to9 the engineers tender enquiry or should he o

11、ffer alternative materials in his written completion of the tender, such a proposal would be a counter offer. McKenzie, in the book referred to above, states, “For a tender to be such that on acceptance a valid contract is created it must be intended to be the whole offer and must not leave certain

12、essential terms open to further negotiation“. NOTE: “Prospective contractor“ means the party or firm who has been advised that, provided that he/it complies, within an agreed time limit, with the engineers specified requirements with regard to alternative cladding (or sheeting) or fasteners, or both

13、, his/its tender will be accepted thus converting him/it into the contractor Period of Validity of Tenders. Ensure that the period of validity of all tenders is suitably extended if delays are likely to occur in obtaining the information and details required in terms of 1.2.3 below or in concluding

14、the tests required by the engineer in terms of Subclauses 7.1.1 and 7.1.4 of SABS 1200 HB. Approval of Data given by Tenderer on Detail Sheets. After a tender has been received and before the award of the contract ensure that a) all relevant information has been provided on the detail sheet(s), if a

15、ny, and that agreement has been reached on all detail data given on the detail sheet(s) (see 1.3.2 and 1.3.7 below); b) when relevant, each detail sheet has been suitably amended where necessary, any variations have been priced and each detail sheet has been signed by the engineer as having been app

16、roved (see 1.2.1 above and Subclause 3.2.2 of Section BB of Part 2 of the code); C) special requirements, if any, have been dealt with adequately and are fully understood and, if any doubt exists, confirm the understanding by the exchange of letters. Tenderers and Approved Manufacturers (Subclauses

17、3.2 and 3.4). Although it is the tenderers responsibility to determine the identity of approved manufacturers, the engineer must make such information available if so requested during the tender period, because certain requirements of the specification are dependant on those of approved manufacturer

18、s (see Subclause 3.2.1 of Section HB of Part 5 of the code). WCUMENTATION Provision for Escalation. Ensure that an appropriate escalation clause is included in the contract documents. (See Subclause 8.2.2 of SABS 1200 AH), and Subclause 1.3.2.2 of Section H.) Detail Sheets and Special Conditions of

19、Tender. When it is considered likely that manufacturers may be able to provide an acceptable cladding that differs in detail from that scheduled or specified in SABS 1200 HB or in the project specification, and also when it is required that the engineer be advised of particular details of the types

20、of material on offer, insert a clause in the special conditions of tender that requires the tenderer to complete one or more detail sheets (included in the document), and draw his attention to the requirements of the project specification covering the completion of such detail sheets (see 1.2.3 abov

21、e, 1.3.7 below and Suhclause 3.2.2 of Section HB of Part 2 of the code). Project Specification Fasteners (Subclause 3.7). On the basis of test results, preferably specify in the project specification the type of fasteners to be used, rather than leaving selection to the contractor. An alternative of

22、fered in the tender (see 1.3.7 below) may be accepted on the grounds of proven successful use in similar applications. (See also 2.2 below and Subclause 3.2.3 of Section HB of Part 2 of the code.) Installation tolerances for cladding and sheeting (Subclause 6.2.2). Take into account the aesthetic ap

23、pearance of the finished structure when giving installation tolerances for cladding and sheeting in the project specification. Inhibiting Wet-storage Stain on Galvanized Sheetinp. Galvanized sheeting materials are very susceptible to wet-storage stain during transit and storage on site. Consider spe

24、cifying that all galvanized sheeting and other materials that are subject to wet-storage stain be coated with a suitable inhibitor during the course of manufacture. Flashings to Protrusions (see 2.5.2 below). Typically, where a protrusion is a circular chimney and is to be flashed with l mm galvaniz

25、ed steel, requirements such as the following may be appropriate: “A galvanized soaker having a dimension on the flat of at least 500 mm, with equal upstand, shall be provided. The soaker shall be pre-made to suit the diameter and slope of the steel chimney. The flat portion of the soaker shall be fi

26、xed to the roof by means of seam bolts after the closers and weather sealant have been placed.“ (NOTE: Where chimneys with high heat potentials are involved, specify a greater dimension on the flat to reduce the possibility of melting of the sealants owing to heat.) l) By H S McKenzie, 3rd edition,

27、published by Juta in 1977. 2) General (structural) . SABS 0120 : Part 3 Section HR-1985 Cladding and sheeting Site Handling of Aluminium Sheetin3 (Subclause 5.2.3). Where the location of the site i5 such that special steps are necessary to ensure that aluminium sheeting is not damaged by a corrosive

28、 or dusty environment or that water is not drawn in between the sheets by capillgry action. specify suitable special precautions. (See also Subclause 3.1.4 of Section AB of Part 5 of the code.) Detail Sheet. When the provisions of 1.3.2 above apply, conpile one or more suitable detail sheets (based

29、on the one given in Annexure 1 of Section HE! of Part 2 of the code) for inclusion in the contract document. DESIGN REQUIREHENTS GENERAL. Design a roof first and foremost to keep out the elements. Except in exceptional circumstances its functional performance will affect its design more than will ae

30、sthetic considerations. Therefore, ensure that the structure to which sheets are to be fixed has been so designed that a) all eaves sheets can be supported as near to their ends as is practicable; b) the unsupported overhang for any type of sheet does not exceed that recommended by the sheeting manu

31、facturer; and C) each sheet at gable ends and v(erges can be supported for the full width of the sheet (sc!e Subclause 5.5.1 of SABS 1200 HB) . Design qalvanized steel cladding and sheeting in accordance with the recommendations of SABS . . . 3, . Because of continuous developments which have taken

32、place within the cladding industry a wide and varied range of roofing and cladding profiles are available today and it is difficult for engineers and architects to keep abreast of progress at all times. Early in the design stage ask manufacturers (who provide extensive technical services) to assist

33、with specifications and general technical matters. DESIGN AND SELECTION OF FASTENERS (Subclause 5.5.3). Selection of the fasteners to be used .is best done by means of tests or based on experience. Give consideration to the recommendations of 1.3.2 and 1.3.3.1 above, and to (a)-(el below, before rea

34、ching a decision. a) Fasteners for cladding may be divided into two broad categories, namely unsophisticated and sophisticated. These categories are defined by the amount of skill needed for installing the fasteners: the drive screw and hook bolt fall into the former category as the drive screw can

35、be applied with a hammer and the hook bolt with a spanner, a hand drill being used if necessary. b) Sophisticated fasteners invariably require power tools or special tools plus a greater degree of skill for satisfactory installation. Both unsophisticated and sophisticated fasteners are availab.1e in

36、 plated steel and other corrosion-resistant materials, e.q. aluminium and stainless steel. However, fasteners cannot be studied in isolation as the seal which is used to prevent leakage is of prime importance. The success of the cladding as a water barrier is only as good as the fastener/seal system

37、. Sophisticated seals are metal and rubber combinations, in many cases purpose-made to suit specific profiled sheets. c) Unsophisticated fasteners such as hot-dip galvanized hook bolts with hot-dip galvanized diamond-shaped washers or bituminized felt washers may be outdated but can still render exc

38、ellent service. (See PSHB 1.2 in Subclause 3.2.3 of Section NB of Part 2 of the code.) d) Fasteners having an electroplated coating of zinc or cadmium have been found to have poor resistance to corrosion. However, self-tapping and self-drilling screws of carbon steel require cadmium plating as the c

39、admium acts as a lubricant when the screws are turned. When using prepainted sheets it is good practice to use fasteners manufactured from corrosion-resistant materials e.g. stainless steels. Specjfy fastener systems having corrosion protection equal to or better than that of the sheeting with which

40、 they are to be used. e) The cost of fasteners, of whatever type, manufactured from corrosion-resistant materials is higher than that of fasteners of other materials. Bear in mind other costs such as the cost of labour, supervision, scaffolding hire, post-contract maintenance and, very important, re

41、placement costs. A fastener that requires less time (and therefore less labour) to install will save costs irk overheads, travelling, etc. and, depending on the type of structure, the use of certain sophisticated fasteners may obviate the use of scaffoldinq by enabling all work to be done from the o

42、utside or from thc top of the roof. Such costs can be calculated and compared. PEAK WIND LOADS. See 5.1 below. DETAILED INSTRUCTIONS (Subclause 5.5). Jnclude detailed instructions (prepared in close I:O-operation with the manufacturer) in the project specification and in the working drawings for the

43、 installation of cladding and sheeting. FLASHINGS (Subclause 5.6) Factory Gutters. If gutter flashings are required to prevent the ingress of water into a building, design a suitable drip flashing giving due cognizance to the sheeting profile and structmal details. However, bending the troughs down

44、to form a water drip is usually sufficient and may obviate the need for gutter flashings. Flashings to Protrusions. Design and specify f lashings for protrusions wherever they occui (see 1.3.5 above) . GUTTERS, IALINUERS AND DOWNPIPES (Subclause 3.8). .So design gutters, launders and downpipes that

45、they can cope with rainfall intensity derived from information obtained by reference to Appendix F of SABS 0160). APPLICABILITY OF OTHER CODES SmS . . .3) and certain sections of SABS 0x60) are relevant to the design of cladding and she(2ting. TFT PROCEDURES The hesC procedures set out in Clause 7 o

46、f SABS 1200 FIB are applicable. 3) Code of practice for the design and installation of profiled sheeting (In course of preparation - Project No. 661/50640). 4) General procedures and loadings to be adopted for the design of buildings. SABS 0120 : Part 3 Section He-1985 Cladding and sheeting QUALITY

47、CONTROL AND OTHER CONSIDERATIONS FAILURES DUE TO WIND WADING. Cladding failures due to wind loading are amongst the nwst colnaon building failures in South Africa. Alnwst without exception these failures havp occurred as a result of insufficient provision for wind loading. The majority of these failures have occurred or have been initiated in regions of high local pressure near the edges of a building. It is important, therefore, that loads on cladding elements be calculated in accordance with the provisions of SABS 01604. 4) See p. 2.