Uniclass is set to change, including Table J – the Common Arrangement of Works Sections (CAWS). Here John Gelder, Head of content development and sustainability, outlines the replacement for CAWS.

Uniclass (1997) is promulgated by Construction Project Information (CPI) externallink, an organization comprising representatives from RIBA, RICS, UKCG, ICE, CIBSE and CIAT. The current version of CAWS externallink, aligning with Uniclass, was published in 1998. However, CPIC's precursor, the Coordinating Committee for Project Information (CCPI), first published CAWS in 1987. CAWS has provided the overall structure for NBS since then, and it has barely changed in all that time. The need for change has, however, been steadily growing. A few years ago a Uniclass Working Group was established to deal with this. On 30 September 2011, the CPI Committee endorsed NBS proposals for a new work sections classification, to replace CAWS (Uniclass Table J), as part of a much broader proposal to unify Uniclass. The new work sections classification provides the overall framework for NBS Create.

Drivers for change

One of the main drivers for change is the need for the classification and specification to accommodate civil engineering and process engineering, along with architecture and landscape. Civil and process engineering projects generally also involve architectural and landscape work. Consider for example the Crossrail project with its tunnels and tracks (civil) and its stations and platforms (architectural). It makes sense for them to all be covered by the one classification, and in the one specification structure. CAWS cannot accommodate this – its size and structure are inadequate to the task.

Another main driver for change is the need for the works classification to cover the description of all works a contractor may carry out, right along the project timeline. Design-build contractors, for example, typically complete the design after planning approval. The systems comprising the building are only partially resolved at this point. The specification therefore needs to be able to describe systems in performance terms. The classification needs homes for every conceivable system. Of course, the contractor may be engaged even earlier, in which case the works might entail design of the building as a whole. This is particularly so for PFI contractors, engaged from inception – the PFI specification needs to be able to describe high-level entities, such as facilities and buildings, in both performance and prescriptive modes. PFI contractors are also retained to operate and maintain the site after handover, so the specification must offer homes for client requirements for both hard and soft facilities management (FM). Facility management contractors also need this content. It makes sense to use the one classification, and the one specification structure, along the entire project timeline. Again, CAWS cannot accommodate this.

The table shows the scope of the new classification compared with that for CAWS. You can see that the table needs to be quite a bit bigger to deal with the two drivers outlined above. Both CAWS and the new work section classification have three levels – group, subgroup and section (e.g. H-4-3 and 35-25-15 respectively). CAWS has homes for an upper limit of 2400 sections (24 x 10 x 10). The new classification has room for 8000 sections (20 x 20 x 20), or more if necessary (e.g. 20 x 20 x 100).

Scope of new Uniclass Work sections table

  Design, e.g. high-level objects such as facilities and buildings Build Operate, e.g. hard and soft FM
Buildings and landscapes Uniclass table J (CAWS)
Civil engineering Uniclass table K (CESMM3)
Process engineering

CAWS has a number of product sections on both the fabric and services sides, but many products have to be described in all the sections that need them, there being no central home for them. This approach leads to repetition of product clauses in the project specification, e.g. particleboard and wood screws, with consequent bulk, multiple handling, and inconsistency. Modern IT allows us to resolve this muddle, through use of hyperlinks within the specification, linking systems to the products that serve them, wherever those products are held. With this in mind we have taken the opportunity of creating 'product supermarkets' – two Groups (for fabric and services) dedicated to the description of all ex-catalogue products, so that there is no repetition of product clauses. Some other factors necessitating a revision of CAWS were described in the article Reclassification, in NBS Journal 08 (May 2006). This change has been a long time coming.

The new classification

The classification comprises 20 Groups, numbered in 5s, each containing up to 20 Subgroups. In turn these contain up to 20 Sections, more in some cases. The Groups are as follows:

  • 00 Project management
  • 05 Districts, facilities and buildings
  • 10 Preparatory systems
  • 15 General structural systems
  • 20 Roof, floor and paving systems
  • 25 Wall and barrier systems
  • 30 Fixed access, tunnel, tower and vessel systems
  • 35 FF&E, signage and general finishing systems
  • 40 Flora and fauna systems
  • 45 Fabric, FF&E and landscape products
  • 50 Disposal systems
  • 55 Piped supply systems
  • 60 Heating, cooling and refrigeration systems
  • 65 Ventilation and air conditioning systems
  • 70 Electrical systems
  • 75 Communications, security, safety and protection systems
  • 80 Transport systems
  • 85 Process engineering systems
  • 90 Services and process engineering products
  • 95 Soft facility management.

Group 00: This Group extends the CAWS concept of 'Preliminaries and general conditions' along the timeline to cover project management of briefing, design, construction and occupancy, for example.

Group 05: This Group provides a home for outline and performance descriptions of a number of high-level entities: regions, districts, infrastructure, facilities or sites, buildings and landscapes, activities, spaces and elements. Requirements for these are typically documented in the early stages of the project, e.g. for briefing and sketch design. Uniclass Table D Facilities externallinkhas been co-opted for many of the subgroups here.

Groups 10-40: These Groups are homes for system sections for architecture, structure and landscape. Group 10 deals with survey, preparation, remediation and temporary works systems, for example. Each section describes everything to do with a system – its outline (i.e. list of component products), performance, execution, completion and facility management. This means that the Uniclass work section classification, unlike the North American MasterFormat externallinkclassification, does not need separate sections for system performance, system commissioning and system FM. The shift to systems on the fabric side of the classification means that we can now provide homes for objects that CAWS has no home for, e.g. structural framing systems. The relationship between the new sections and current CAWS sections is variously one-to-one, many-to-one, one-to-many and many-to-many.

Group 45: This is the 'product supermarket' for architecture, structure and landscape systems. As far as possible the products are grouped in an application-neutral way – the same type of particleboard can be used for flooring, sheathing, joinery and lining systems, for example.

Groups 50-85: These Groups are homes for system sections for engineering services and process engineering. The engineering services Groups are closely aligned to those in CAWS. For the most part, the relationship between the new sections and current CAWS sections is one-to-one.

Group 90: This is the 'product supermarket' for engineering services and process engineering systems.

Group 95: Based on BS EN 15221-1:2006 Facility management. Terms and definitions, this Group is for specification of contracted activities such as cleaning, security, hospitality and logistics services.
Section codes identify the Group, Subgroup and Section, just as they do in CAWS. NBS Create extends the Uniclass three-level classification to Subsection and Clause level, and below, e.g:

Group 25 Wall and barrier systems
Subgroup 25-85 Internal wall covering and finish systems
Section 25-85-60 Plaster coating systems
NBS Subsection   System outline
NBS Clause 25-85-60/150 Multicoat plaster system
NBS Item   First coat: [...]

Systems and trades

Systems and trades (typical subcontracts) generally align. For example, 75-60-05 Access control systems are designed, supplied and installed by specialist access control subcontractors (ideally approved by NSI externallinkor SSAIB externallink– this is a recognized trade in the UK). 20-55-80 Rolled carpeting systems are supplied and installed by specialist subcontractors (ideally certified by CFI externallinkor a member of CFA externallinkor NICF externallink– this is also a recognized trade in the UK). This means that a systems classification can map directly to a trades (work section) classification – the move to systems does not mean that we have lost the usefulness of CAWS in describing the work of trades. The new classification manages to deal with both systems and trades at the same time.

NES and SMM7

CAWS is used elsewhere than NBS, notably by NES (National Engineering Specification externallink, published by Amtech) and SMM7 (Standard Method of Measurement, published by RICS externallink). Both NES and RICS are on the Uniclass Working Group, and so are supportive of the proposals described here.

RICS has been developing its replacement for SMM7 for some time, since before the inception of the Working Group in fact. This work is intended to distance RICS' methods of measurement from any particular national classification system, and from CAWS (UK-specific) in particular, as RICS wants to support the business of measurement along the project timeline, and globally. The NRM (New Rules of Measurement externallink) is aligned to an elemental classification with this in mind, and to the whole time line, and so has broken from CAWS. Interestingly the new work section classification, being explicitly systems-based and designed to serve the complete project timeline, will facilitate mapping to the NRM in a way that would have been difficult with CAWS. That is, the new classification should help with UK take-up of the NRM, accelerating the move away from SMM7.


If this all seems a bit much, you might be able to relax a bit. CAWS and the new work section classification will co-exist for a while, just as NBS Building and NBS Create will co-exist. Moving to NBS Create will, however, require you to also move to the new Uniclass Work sections table.