Organising the description by elementary item
The concept
An elementary item is the smallest coherent unit of work whose cost and quantity can be calculated independently. The pricing schedule is organised around that notion, and it is the specification that gives each item its technical content.
For each item the specification must state the complete designation, materials, dimensions, finishes, the technical requirements including the standards and codes of practice, the method of execution, and the tests and checks required. It is the design team that defines the items and their boundaries; the contractor adapts to them.
The typical structure of a specification
| General matters | The scope of the package, the contractual reference documents, drawings, codes of practice, standards in force, the list of interfaces with other packages, and the coordination arrangements. |
|---|---|
| Description of the elementary items | A precise technical description of each item, in the logical order of construction: materials, references, technical characteristics, conditions of installation. |
| Extras | Extras are items that do not appear explicitly on the drawings but are necessary for the work to be properly finished. They must be listed in the specification and appear in the pricing schedule as distinct items. |
| Tests and checks | Test certificates to be supplied, manufacturers' data sheets, certificates of conformity, conditions of partial acceptance. |
| Documents to be handed over | The as-built file, record drawings, maintenance instructions, manufacturers' warranties. These documents are contractual deliverables on the same footing as the works. |
The extras: the work that is not on the drawings
An extra is work that does not appear explicitly on the drawings but must be carried out for the works to be properly finished to the rules of the trade. It is a complementary elementary item, in the same place as another item already provided for.
Ignoring extras in the specification is a major source of dispute. If they are not mentioned, the contractor can legitimately claim they are not part of its contract and seek a variation. Examples by package:
| Plastering | Incorporating electrical conduit into the partitions, with the plasterer supplying the labour and the electrician the material; protecting partition bases around wet rooms; protecting external corners; fixing door frames as work proceeds, with the plasterer's labour and the joiner's frames. |
|---|---|
| Tiling | Threshold strips between different floor finishes; a perimeter movement joint; screed protection in wet areas; making good the skirting around pipework. |
| Painting | Priming joinery before it is fixed, for protection during construction; protecting glazing while painting frames; making good the fixing holes left by scaffolding. |
| Masonry | Bedding external door and window frames fixed by another package; making good the chases cut by the services trades; sealing service penetrations through fire-resisting construction. |
A practical rule: for each elementary item in your specification, systematically ask, "what will the contractor have to do beyond what the drawing shows for the work to be properly finished?" The answer gives the list of extras to mention.
The interfaces between packages: defining who does what
An interface is the zone where two packages meet and where the division of tasks must be clearly defined to avoid duplication, omission and dispute.
| Plastering with internal joinery | The plasterer fixes the frames as work proceeds, supplying the labour; the joiner supplies the frames and fits the doors, locks and adjustments. The painting package paints the joinery. |
|---|---|
| Plastering with electrics | The plasterer incorporates the conduits and boxes, supplying the labour; the electrician supplies the materials and carries out the wiring and the fitting of the accessories after chasing. |
| Tiling with structure | The structural contractor lays the levelling screed; the tiler lays the finishing screed and the tiling. The boundary must be defined precisely, with or without the screed? |
| Plumbing with structure | The structural contractor forms the openings and sleeves to the services drawings supplied by the design team; the plumber runs the pipework through them. |
| Mechanical services with electrics | The electrician provides the supplies to the mechanical plant; the plumbing and heating contractor makes the hydraulic and air connections. The capacities and connection points must be defined in the tender documents. |
The rule to remember: each interface must be addressed in the specification of every package concerned. If an interface is mentioned in only one specification, the other package can claim it does not concern them.
The administrative conditions
| Duration and programme | The start date, the overall duration, intermediate milestones, delay damages. The standard formula is one three-thousandth of the contract sum per calendar day of delay. |
|---|---|
| Price and revision | The nature of the price, firm or revisable; the applicable revision index; the conditions that trigger revision. On private contracts revision is not automatic and must be contracted for. |
| Payment terms | The frequency of valuations, monthly; the payment period, 30 days on public contracts and negotiable in private work; the arrangements for checking and endorsing the valuations. |
| Retention | 5 % of the contract sum, held until a year after handover. It can be replaced by an on-demand bank guarantee, often required by contractors on large contracts. |
| Insurance | Professional and ten-year liability cover are mandatory. The conditions must state the minimum levels required and the effective date, to be checked before work starts. |
| Handover | The arrangements for the pre-handover inspection, the maximum period for clearing defects, 60 days is common practice, and the treatment of defects not cleared. |
The hierarchy of documents and the errors to avoid
Where the contract documents contradict each other, the contractual hierarchy determines which prevails. The usual order: form of agreement, administrative conditions, technical specification, drawings, pricing schedule. The conditions should state that order of priority explicitly.
| A copied specification | Generic specifications not adapted contain references to products withdrawn from the market, superseded codes of practice or requirements incompatible with the project. The result: offers that cannot be compared, and disputes. |
|---|---|
| Extras missing | If the extras appear neither in the specification nor in the pricing schedule, the contractor can legitimately claim a variation to carry them out. |
| Interfaces undefined | Failing to define the interfaces creates gaps, work nobody takes on, or duplication invoiced twice. |
| Derisory damages | Without significant and enforceable delay damages, contractors have no contractual incentive to respect the programme. |
| Brands imposed without "or equivalent" | On public contracts, imposing a brand without that wording is unlawful and can invalidate the procedure. |
Related articles: How a construction tender works · Subcontracting in works contracts · Construction procurement and tendering
The drafting practices described correspond to French professional standards. Complementary technical source: Widloecher and Cusant, Descriptifs et CCTP de projets de construction, Eyrolles, 3rd ed. 2020.
The nature of the figures quoted
The percentages and amounts quoted on this page are orders of magnitude for framing, not measurements. They illustrate mechanisms and proportions, and they substitute neither for a tender exercise nor for an estimate prepared on drawings.
Articles liés
Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.