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4. Specification for larger projects

4.1 Structuring for ease of use

4.1.1 Introduction

Section 3.3.2 recommends that on larger projects drawings and bills of quantities (if used) identify and cross-refer to the different kinds of work but do not specify them. It follows that an overriding consideration is the need for the specification to be referred to easily, and for the contents to be co-related speedily and certainly with the drawings and any quantities.

4.1.2 Work sections

On larger projects the specification is used by a wide variety of people and organisations. Whilst some (e.g. main contractor, management contractor, project manager, architect, clerk of works) will need to have easy reference to the complete specification, the many specialists, subcontractors and suppliers will be concerned only with the information relevant to them. The specification should therefore be arranged in sections that relate closely to the pattern of subcontracting, making it easier to divide up and distribute to obtain estimates and arrange for construction of the various types of work.

The Common Arrangement of Work Sections (CAWS) was devised with this in mind, and should be followed closely. CAWS forms Table J of Uniclass (RIBA Publications 1997), and is published with section definitions as a separate document (CPIC, Second edition 1998).

The classification is set out in three levels as follows:

• Level 1: Group e.g. M Surface finishes
• Level 2: Sub-group e.g. M1 Screeds/Trowelled flooring
• Level 3: Work section e.g. M13 Calcium sulfate based screeds

CAWS includes about 300 work sections, reflecting the large range of specialists and subcontractors that now exist. Each work section has a detailed definition in order that project documents can be consistent in their arrangement and to help ensure that gaps and overlaps between sections do not occur (an example definition is given in Figure 4.1). The work sections are smaller and more specific than the traditional 'trades', so only 20% to 30% of the 300 sections will apply to a typical project.

It is intended that project specifications and bills of quantities use level 1 and level 3 headings and codes, but not level 2. The simple alphanumeric coding of CAWS facilitates looking up of specification cross-references given on the drawings, in bills of quantities, instructions, correspondence, telephone calls, etc (see Section 4.1.5).

Figure 4.1 Example definition of a CAWS work section

CAWS groups Y and Z provide 'reference specification sections'. The purpose of these is to reduce repetition by giving specification that is bulky and common to several 'work' sections, e.g. Y20 Pumps and Z21 Mortars. The reference specification section can then be invoked by reference in the relevant work sections. Variable specification, e.g. pump ratings, mortar mixes, should be given in the work sections rather than the reference specification sections.

4.1.3 Within the work sections

Types of clause

Within each work section the information should be coherent and in a rational sequence. Clauses should be of the following types:

• Introductory information: Important for sections that are likely to be or are required to be the subject of specialist subcontracting. May include description of the work, list of drawings, information to be submitted.
• Work type clauses: These state the main specification variants (either prescriptive, performance, or a combination of the two) and how they are combined in different types of finished work, facilitating cross-reference from elsewhere in the project documents. For example Section R12 DRAINAGE BELOW GROUND may include a clause R12/121 PIPELINES FOR GENERAL USE. This could specify the type and size(s) of pipe, the assumed type of subsoil, and the type of bedding (see Figure 4.3).
• Work type 'support' clauses: These are for use where specification variants, e.g. types of bedding for drainage pipelines, involve lengthy description. They can be invoked by reference in the work type clauses, so that the latter can be brief and only minimally repetitious (again see Figure 4.3).
• General 'support' clauses: These specify things that are not normally 'variants', e.g., in the case of DRAINAGE BELOW GROUND, excavation and backfilling, testing and inspection.
• Equipment and accessories clauses: These cover items that are likely to be priced separately, and therefore not included in the work type clauses. They should be as self-contained as possible, again to facilitate cross-reference, e.g. R12/610 HORIZONTAL BACK INLET GULLY, specifying the gully, trap and grid.

Clause structure

For some purposes sections will be read from beginning to end, but for much of the time specifications are used in the manner of an encyclopaedia to check on particular products or other requirements. Helpful headings and keywords are therefore essential.

The main principles of clause structuring are:

LENGTH OF CLAUSES: Strike a balance between too short (staccato) and too long (rambling). Two to six lines is about right, but can be more if sub-itemised.

SUB-ITEMISATION can be used to:

• break up a long clause, making it easier to read;
• set out a series of attributes or properties;
• describe a series of sub-operations;
• set out a range of options or alternatives.

CROSS-REFERENCING: Where there is a need to cross-refer to the specification for information on a particular item of construction, a single clause that deals with every specification variant of that item should be provided, so that the reference can be simple (see above - work type, equipment and accessories clauses).

KEYWORDS: To assist scanning pages by eye to find particular items of information, each clause should be devoted to a single subject, with one or more words in upper case at the beginning, chosen to reflect the subject. Keywords will usually be the generic name of the product, the feature or part of the work being constructed, or the name of the operation. It is usually unhelpful to choose a verb, e.g. 'STAIR NOSINGS: fix with _ _ _ _' rather than 'FIX stair nosings with _ _ _ _'.

SEQUENCE of clauses should be clear and rational in the context of the headings. This should show through in the keywords.

TERMINOLOGY: Where appropriate use terms defined in BS 6100 'Glossary of building and civil engineering terms'. Terms and acronyms defined in preliminaries (e.g. 'SO', 'equivalent approved') should be used consistently.

ADDRESS THE CONSTRUCTOR DIRECTLY: 'The contractor shall' and similar phrases are not necessary.

QUALITY OF WRITING: Write directly, simply and clearly. This can be difficult to achieve, and use of well written, carefully considered standard clauses usually offers significant advantage over writing from scratch.

4.1.4 Location information

The specification will define the various kinds and qualities of work, and can also give information on where they occur to facilitate correlation with the drawings. Work type clauses in particular (see Section 4.1.3 above) can include location information, e.g.:

• FACING BRICKWORK BELOW DPC
• PATENT GLAZING TO CONSERVATORY
• SUSPENDED CEILING TO MAIN GALLERY

Section 3.1.2 discussed location information schedules, traditionally regarded as drawings, and proposed that they usually can and should now be regarded as part of the specification. On a large project there can be many such schedules, most of which give significant specification information (rather than just references to the specification), and are confined to one CAWS section. Such specification information can be conveniently included as work type clauses in the relevant specification section, e.g. Doors (L20), Windows (L10), Ironmongery (P21), Sanitary fittings (N13), Light fittings (V21), Radiators (T30), Manholes (R12), Piles (D30), Exterior planting (Q31).

To be included in the specification, the information needs to be formatted to go onto A4 paper, or a larger size reduced to A4. The 'matrix' format traditionally used on drawn location schedules can, if desired, be used, but the number of columns will be strictly limited. An 'itemised' format is usually more suitable, and is consistent with the presentation of work type clauses elsewhere in the specification - see Figure 4.2.

Figure 4.2 Itemised format work type clauses

On most larger projects there are three cases where the location information usually relates to several CAWS sections, and can be sufficiently large to merit special treatment: doors, internal finishes, and fittings and fixtures. In these cases the information can be presented more concisely and used more easily if it is broken down into two levels:

• Work type clauses in the relevant CAWS work sections as described above, and
• Location schedules (for e.g. Doors, Internal finishes, Fittings and fixtures) included in the specification under CAWS Group B2, and consisting of references to the relevant work types. Examples are given in Figure 4.3.

Figure 4.3 Location schedules included in the specification

Bending schedules for concrete reinforcement are another special case. They contain graphic diagrams, and give shape and size rather than specification quality. They may be regarded as part of the concrete reinforcement drawings, but if preferred they can be produced on A4 paper and appended to section E30 of the specification.

4.1.5 Linking the documents together

Drawings should be annotated with precise and succinct 'identification' cross-references, e.g. 'Facing blockwork F10/110' (see Section 3.3.2), but not indiscriminately. Each reference should be for a good reason. References should, in the main, be on assembly drawings.

The example in Figure 4.4 has been produced specifically to illustrate specification referencing of drawings; it does not purport to be complete. The highlighted references, e.g. R12/121 are to the selected specification clauses given in Figure 4.5.

Figure 4.4 Annotation of drawings with specification references

Figure 4.5 Clauses from Section R12, referred to in Figures 4.4 and 4.7

To ensure consistency in the drawings for a project, the cross-references that will be needed can be predetermined, included in a list, and copied onto the drawings as required. The list can also be used to ensure that the item descriptions in bills of quantities tally with the drawings annotations, to prevent cost significant discrepancies and divergences. Figure 4.6 shows part of such a list.

Figure 4.6 Example specification reference list

Where bills of quantities are provided, the SMM7 General Rules specifically permit cross-reference to drawings and specification in lieu of full description. Figure 4.7 gives an example.

Figure 4.7 Bill of quantities with specification references

Arranging the bill of quantities by CAWS will:

• Make it easier to read the quantities and specification together.
• Facilitate distribution of the corresponding parts of quantities and specification to specialists, subcontractors and suppliers.
• Mean that references to the specification given on the drawings will also give easy reference to the quantities.

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