BS_1722-2-2020.pdf

EXPERT COMMENTARYContentsPage1 Overview1.1 Reasons for change21.2 Summary21.3 Also2 Main commentaryP3 Wider context4 Conclusion35 Further reading心AuthorTechnical reviewersDisclaimer4Summary of pagesThis document comprises a front cover,and inside front cover,pages i to ii,pages 1 to 4,an inside back cover and aback cover.THE BRITISH STANDARDS INSTITUTION 2020-ALL RIGHTS RESERVED IEXPERT COMMENTARY2 Main commentaryThe standard gives the minimum requirements for materials and workmanship for the more commontypes of strained wire fencing in order to ensure satisfactory service for the client and to assistmanufacturers and installers by eliminating unnecessary variations in the demands of clients.It further highlights improvements in fencing,based on the mechanics of fencing and greater use ofhigh tensile wire in professional fencing.The previous version of the standard concentrated on theuse of mild steel as the main product,which has the drawback that it has to be tensioned annually,even though this is rarely mentioned in grant or specification documentation.The previous standard focused heavily on line wire and droppers that have in subsequent yearsbeen largely replaced by mesh netting,so the reduction of this section to a reduced number of coreinfrastructure usage areas is reflected in the new Table 1.The move away from concrete posts to wood and metal has seen the specifications of fencing change,and the machinery used has evolve to further change the installation process and enhance therequirements for achieving the recommended tensions.There are examples of minimum constructionrequirements in Clause 5,Installation,with updated drawings as Figures 1 and 2.The changes in materials,higher mechanization and the more common use of high tensile wire havebenefited the end-user by enabling a fence that does not need to be tensioned annually to keep itfunctional,but there is an increase in requirements for materials and methods of erection to allow itto withstand the added tension on the fence line.Examples are given in Tables 3,4 and 5.The length of fence lines with mesh fencing has also increased,so reducing costs but increasingthe size and functionality of straining structures needed and also reducing the individual numberrequired to achieve the desired fence.This is reflected in the revised standard.With high tensile wehave fences that retain greater strain for a longer period.Notes on this can be found in Subclause 5.1of the standard.Although mentioned in the previous version of the standard,the use of hard stapling should beeradicated as a practice.This is highlighted in the updated standard and should be included in anyspecifications that use wire as non-conforming practice to achieve the required service life of allstrained wire fencing.Suitable attachment methods to protect the wire coating are included in theupdated standard.Hard stapling is a significant cause of wire deterioration,so weakening the life ofwire fencing.Subclause 4.3.3 clearly states that wire should have free movement,and the correct useof staples is further explained in Subclauses 5.3.1 and 5.4.2.Hard stapling also compromises the structural integrity of a fence due to twisting,causingmalfunction of strainers,so to achieve the required tension needed for the prescribed noted periodit is suggested that it not be used in any circumstance.Only attachment methods for strainershighlighted in Subclause 5.4.1 of the standard should be followed to achieve a suitable fence.As the range of wire mesh sizes has expanded from forestry and agriculture to include a largernumber of species,the introduction of species-specific mesh and the removal of general netting haveresulted in more comprehensive requirements for wire mesh fencing.Table 2 clarifies the specifictype of wire mesh to use for which animal group.3 Wider contextStrained wire fencing is required to perform under varied conditions,in terms of soil types,topography,species that are to be retained or separated,and materials used.The revised standarddetails the requirements and recommendations to be followed to allow industry sector professionals2 THE BRITISH STANDARDS INSTITUTION 2020-ALL RIGHTS RESERVED