National Structural Steelwork Specification For Building Construction 7th Edition Pdf

[Verline Wesolowski]

The7th Edition, 1st Revision of the National Structural Steelwork Specification (NSSS), launched on the 3rd October 2023 continues to meet its objective of achieving greater uniformity in steelwork contract specifications and is recognised as a document that can be incorporated readily into contract documentation to specify acceptable standards for the fabrication and erection of steelwork structures for buildings.

On the 2nd April, RQSC for Buildings was incorporated into the specification, which on the 3rd October 2023 has bceome a mandatory clause. By including a Registered Qualified Steelwork Contractor (RQSC), you are specifying a company that has been assessed and proved its competency, capabilities and safety, thus providing assurance to clients.

It can be used for all types of building construction designed for static loading and is based on Execution Class 2 structural steelwork designed in accordance with BS EN 1993-1-1 or BS 5950 and executed in accordance with BS EN 1090-1 and BS EN 10902. Annexes for Execution Class 3 for static and fatigue structures are also included.

To ensure that the constructional steelwork industry is ready to meet the new challenges presented by the Building Safety Act 2022, BCSA has revised the 7th edition of the National Structural Steelwork Specification for Building Construction.

The National Structural Steelwork Specification for Building Construction (NSSS) is primarily a construction (or execution) specification but also acknowledges the common contractual situations where the steelwork contractor designs the connections (and in some cases the members as well) - it includes checklists of information that the contractor needs to carry out design.

Following the tragic Grenfell Tower fire and the call from Dame Judith Hackitt for industry not to wait for legislation, the BCSA said it and the wider constructional steelwork community decided to take ownership of the specification, application and inspection of intumescent paint systems.

Section 10 of the NSSS now includes comprehensive information on intumescent paint systems and to improve quality, it encourages the paint systems to be applied in the workshop rather than on-site. Other significant changes include a mandatory requirement for all steelwork contractors to put in place a third-party certified welding quality management system to BS EN ISO 3834.

The main body of the NSSS is limited to Execution Class 2, but this version also contains an Annex of the requirements for Execution Class 3 for static structures and an Annex giving general guidance on Execution Class 3 for buildings subject to fatigue, such as crane supporting structures.

To allow steelwork contractors time to put in place the necessary third-party systems to comply with the Specification it has been decided that the NSSS will not come in to force until 1st January 2021.

Hard copies of the 7th edition of the NSSS, which now includes BCSA member listings, can be obtained from the BCSA Bookshop from Monday 14th September and are priced at 20 for BCSA members and 25 for non-members.

The purpose of a structural steelwork specification is to state what materials and products should be used and how work (fabrication and erection) should be carried out, in order to ensure that the completed structure meets the designer's assumptions and the client's needs. Design standards, such as the Eurocodes, give design rules that are valid only if strength, ductility, dimensional accuracy and freedom from defects are within presumed limits. The performance of a structure required by regulations will also only be achieved when construction is within presumed limits.

The complete 'execution specification' for a structure comprises a range of contractual documents, including drawings, a general specification with technical requirements for supply of materials and products and for workmanship, and project-specific requirements for the individual structure.

Rules for the design of steelwork are given in Eurocode 3[1] Design of steel structures. Within Part 1-1 of that Eurocode (BS EN 1993-1-1[2]), the following basis assumption is stated: "fabrication and erection complies with BS EN 1090".

Conformity with the requirements in Part 1[3] (which are general statements, referring to the other Parts for detailed technical requirements), when formally declared, permits UKCA marking of the structure.

The technical requirements in Part 2[4] are comprehensive, covering all types of structural steel (including stainless steel) and types of structure (buildings, bridges, masts, cranes, etc.). It includes references to European standards (adopted as British standards and issues as BS EN) for products, welding, testing and corrosion protection. Products manufactured in accordance with UK designated standards are individually UKCA marked.

All manufacturers of products covered by UKCA_marking must have a Certified Factory Production Control system in place to the relevant UK designated standard and have been given approval by a UK Approved Body to apply the UKCA mark.

Manufacturers must also make available a UK Declaration of Performance (DoP) when a UKCA marked product is placed on the market. The UK DoP serves to deliver the information about the essential characteristics of the product that the manufacturer wants to make available. The manufacturer, by drawing up a UK DoP, assumes the responsibility for the conformity of the construction product with the declared performance.

Because BS EN 1090-2[4] is a comprehensive document, for all steel products and types of structure, it includes numerous instances where options need to be selected or alternatives specified. A summary list of all the options and alternatives is included in an Annex to that Part: many of them are not relevant for ordinary building structures.

It is therefore necessary to draw up a set of project-specific requirements that supplement BS EN 1090-2[4]. For bridge structures in the UK, the Specification for Highway Works[5], or Network Rail's Specification for structural steelwork[6] (which is very similar), will be suitable for most highway and railway bridge projects respectively. For building structures the National Structural Steelwork Specification for Building Construction (NSSS) serves a similar purpose. The NSSS is discussed further below.

Even when the NSSS is used for building structures, some project-specific requirements will still be needed and the NSSS defines the "project specification" as comprising the NSSS, with qualification where necessary, together with Part 1[3] and Part 2[4] of BS EN 1090.

Considerable effort over many years has been spent by the industry in developing the National Structural Steelwork Specification for Building Construction (NSSS). The NSSS is primarily a construction (or execution) specification but also acknowledges the common contractual situations where the steelwork contractor designs the connections (and in some cases the members as well) - it includes checklists of information that the contractor needs to carry out design,

The NSSS was originally developed for use with structures designed in accordance with BS 5950-1[7] but the 5th Edition covered structures designed in accordance with either BS 5950-1[7] or Eurocode 3[1]. From July 2014 onwards, all construction products had to be CE marked and from that date, the 5th Edition was available only in a CE marked version for use with structures to be executed in accordance with BS EN 1090-2[4]. The 6th Edition, published in 2017, similarly covered structures designed in accordance with either BS 5950-1[7] or Eurocode 3[1] and executed in accordance with BS EN 1090-2[4], as does the current 7th Edition which was published in 2020 and came into force on 1st January 2021. The main changes between the 6th Edition and the 7th Edition are briefly described in the following section.

These topics present, in a more concise manner, the requirements in BS EN 1090-2[4] for orthodox building structures. The requirements given in the NSSS should not conflict with those in BS EN 1090-2[4], but should there be conflict, the NSSS takes precedence as it is likely to be more onerous.

The National Structural Steelwork Specification clarifies and aids the process of translating designer's requirements into specific work instructions for execution. Specifiers are encouraged to use the NSSS as the default specification for all steel building structures.

The requirements for protective treatment (both corrosion and fire) have been extensively modified and include updated requirements for corrosion protection systems and new clauses on the specification, application and testing of intumescent coatings. To improve quality, the NSSS encourages the paint systems to be applied in the workshop rather than on-site.

The 1st edition of the Sustainability Specification for structural steelwork for building construction was published by BCSA in January 2022, and is freely available here. Due to come into force on 1st June 2022, this document will constitute a new Annex J to the National Structural Steelwork Specification for Building Construction (NSSS) when revised in its 8th edition.

Given demands to promote more sustainable construction, and particularly in the context of the climate emergency, this document specifies general requirements and practices for achieving environmentally sustainable steel building construction. It supplements the requirements of Clauses 1 to 11 of the NSSS and includes guidance on both the sustainable design of structural steelwork and the specification for sustainable fabrication of structural steelwork. It requires all relevant Environmental Product Declarations (EPDs) to be submitted for new steel products, as well as for corrosion and fire protection systems and cover several topics, including:

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