Larger projects

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).

K40 Demountable suspended ceilings False ceilings of dry construction comprising a membrane of tiles, panels, trays, etc., supported by exposed or concealed suspended metal grids. The membrane is normally demountable, in part or in whole, to give access to the ceiling space. Lighting, ventilation, fire prevention and other services may be integrated with the suspended ceilings. Included Suspension and framing members Self finished tiles, boards, panels or strips Integral heating, ventilating, lighting or fire prevention fittings and outlets Perimeter trim (where to be provided by suspended ceiling specialist) Acoustic insulation Access panels Cavity fire barriers Sound barriers (coinciding with partitions) Air plenum barriers Reveals to rooflight openings, changes of level Stretched plastics membrane ceilings Excluded Soffit linings on battens, etc. fixed direct to underside of slab (Relevant sections, G20, K10, K11, K20, etc.) Dry lined plasterboard ceilings (Plasterboard dry lining/partitions/ceilings, K10) Wet plaster ceiling membranes including plasterboard backings (Plastered/Rendered/Roughcast coatings, M20) Sprayed mineral fibre coatings, M22 Metal lathing for plastered and sprayed mineral fibre ceiling membranes (Metal mesh lathing/Anchored reinforcement for plastered coatings, M30) Site decoration (Painting/Clear finishing, M60) Perimeter trim, where not provided by specialist (Unframed isolated trims/skirtings/sundry items, P20) Holes/Chases/Covers/Supports for services, P31 Connections to services installations (Relevant section, e.g. S63, T30, T40, U10, V21 etc.) Second edition changes Title amended. Plasterboard dry lined ceilings now included in section K10

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.

L20 DOORS 210 EXTERNAL TIMBER DOOR FRAMES: - Timber species: to BSI PAS 024 - Preservative treatment: organic solvent as section Z12 and BWPDPA Commodity Specification C5 - Moisture content on delivery: 13 to 19% - Finish as delivered: primed for painting - Fixing: at 600 mm centres and 300 mm from each corner 211 INTERNAL TIMBER DOOR FRAMES GENERALLY: - Timber species: _ _ _ etc.

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.

B2 LOCATION SCHEDULES B20 DOOR SCHEDULE   DOORS 1, 5, 14, 17: - Type/ location: external entrances - Door frame: Timber, Type L20/210, Gloss paint M60/205 - Door leaf: Glazed hardwood, L20/314, Varnished M60/302 - Lintel: Pressed steel, F30/6   DOORS 2, 7, 8, 12: - Type/location: _ _ _ etc. B21 INTERNAL FINISHES SCHEDULE   ROOM 1: ENTRANCE HALL: - Floor: Wood block M42/102 - Skirtings: 150mm MDF P20/401, Gloss paint M60/205 - Ceiling: Suspended ceiling K40/113 - Walls generally: Dry lining K10/101, Wallpaper M52/104 - North wall between doors 6 and 7: Ceramic tile logo M40/301   ROOM 2: GENERAL OFFICE: - Floor: _ _ _ etc.

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

R12 DRAINAGE BELOW GROUND   To be read with Preliminaries/General conditions.   GENERALLY 100 EXISTING DRAINS: - Before starting work, check invert levels and positions of existing drains, sewers, inspection chambers and manholes against information shown on drawings and report any discrepancies to CA. - Adequately protect existing drains and maintain normal operation during construction. 106 IN SITU CONCRETE: - Unless specified otherwise, in situ concrete for use in drainage below ground to be to BS 5328, mix GEN 1 or an equivalent or better mix subject to approval. - Different mixes may be used for different parts of the drainage work.   TYPE(S) OF PIPELINE 121 CLAY PIPELINES FOR GENERAL USE: - Pipes, bends and junctions: Vitrified clay to BS EN 295-1, with flexible joints, Kitemark certified. Strength: FN 40. Size(s): DN 100 and 150. Jointing: Polypropylene sleeve. - Assumed type of subsoil: Stiff to firm clay. - Bedding class D, natural bed. 121A CLAY PIPELINES FOR SHALLOW PIPES UNDER AND NEAR BUILDINGS: - Pipes, bends and junctions: Vitrified clay to BS EN 295-1, with flexible joints, Kitemark certified. Strength: FN 40. Size(s): DN 100 and 150. Jointing: Polypropylene sleeve. - Assumed type of subsoil: Stiff to firm clay. - Bedding class Y, concrete surround.   EXCAVATING/BACKFILLING 205 EXCAVATED MATERIAL: Unless otherwise specified, set aside turf, topsoil, hardcore, etc. for use in reinstatement. 210 LOWER PART OF TRENCH: From bottom up to 300 mm above crown of pipe the trench must have vertical sides and be of a width as small as practicable but not less than external diameter of pipe plus 300 mm or larger dimension if specified.   (Continues)

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.

Highdown Centre: specification reference list Repair and repoint boundary wall C41 Remove greenhouse foundations D20 Granular fill D20/2Concrete for foundations E10/100 Concrete for ground floor E10/101Concrete for upper floor E10/102 Bar reinforcement E30 Anchor bolts E42 Common brickwork F10/310 Facing brickwork below dpc F10/390 Facing brickwork above dpc F10/110 Blockwork F10/350 Damp proof course F30/310 Cavity closer F30/180 Wall ties F30/212 Cavity insulation F30/151 Precast sills F31/110 Steel trusses G10 (Size) untreated (studding/framing/grounds) at (centres) G20/205 (Size) treated (rafters/joists) at (centres) G20/210 (Size) treated (wall plates/purlins/bracing) G20/210 Structural glass façade H13 Fibre cement slating H61/120Ridge H61/770 Hips H61/525 Eaves H61/355 Lead flashing H71/310 Sheet damp proof membrane J40/130 Dry lining K10/125 Timber strip floating floor K21/111 WC cubicles K32/120 (List incomplete – remainder not given for sake of brevity)

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.