What PRO is for
APD settled the technical choices and assembled the planning file. PRO goes further: it produces documents precise enough that any competent contractor can price the work without ambiguity.
It is the most demanding stage in documentary output. It engages the architect, in construction drawings and detail books, the economist, in specifications, quantities and priced bills, and every technical consultant, in their own specifications, service drawings and schematics. Coordination between those outputs is critical: an omission on a drawing reappears in the specification, then in the contract, then on site as a variation.
What separates PRO from APD
| Drawings | APD: 1:100, enough for the planning application. PRO: 1:50 with details at 1:20, every element locatable and measurable. |
|---|---|
| Written documents | APD: an outline specification of the works. PRO: complete technical specifications package by package, with full technical requirements. |
| Quantities | APD: by functional element, ±10 %. PRO: by individual element, and a contractual reference. |
| The economist's role | APD: commitment to the forecast cost. PRO: drafting the specifications and quantities, coordinating the consultants, reading the drawings back. |
| End purpose | APD: planning permission and financial commitment. PRO: a pack that allows contractors to be invited to tender. |
PRO drawings: what they must carry
A PRO drawing is not an APD drawing with a new title block. It must carry everything a contractor needs in order to price the work and then build it.
What belongs on a PRO drawing
- ℹ The make-up of every wall: type and thickness of each partition or wall, blockwork, plaster board on studs, concrete, numbered and referenced on the drawing.
- ℹ Floor finishes room by room: tiling, timber, resin, carpet, stated on the drawing or in an associated room schedule.
- ℹ Wall and ceiling finishes: paint, wall tiling, suspended ceilings with type and height, acoustic panels.
- ℹ Door and room numbering: indispensable as soon as a project has more than a handful of rooms. Without it, the specifications and the site both become a source of confusion.
- ℹ Sanitaryware set out: basins, WCs, showers, baths, positioned precisely enough to be connected.
- ℹ Principal builder's work openings: risers for ductwork, routes for electrical services, ducts for external services.
ℹ The golden rule of a PRO drawing: whoever writes the specifications must find on the drawings everything the contractors will need A good economist does not write a specification blind. They write it with the drawings in front of them and check that every item described is consistent with what is drawn. An item in the specification but absent from the drawing will be disputed. An item on the drawing but absent from the specification will be missing from the bids and will become a variation. Where the drawings fall short, the economist must ask for them to be updated before finalising the written documents, not afterwards. A specification written on incomplete drawings is a delayed-action problem.
The structure of a French technical specification
The CCTP, the particular technical specification, is the centrepiece of the tender pack. Package by package, it describes everything the contractor undertakes to carry out for the price of its bid. Drafting it engages the design team's liability directly: an item badly described or left out can lead to a dispute or to an expensive variation.
A typical specification structure
| Article 1, scope | Defines the extent of the package, the contractual reference documents, standards and applicable codes of practice, and the position on subcontracting. |
|---|---|
| Article 2, general description of the works | A synthetic presentation of the package, its interfaces with neighbouring packages, and the general site arrangements for that trade. |
| Article 3, materials and products | Technical requirements for the materials: reference brands or equivalent, minimum characteristics such as thermal resistance, acoustic performance or reaction to fire. |
| Article 4, methods of execution | Description of the working methods, the applicable codes of practice, and the conditions under which the work may proceed, temperature, humidity, substrates. |
| Article 5, detailed items | A description element by element, with location and indicative quantity. This is the heart of the document. |
| Article 6, documents to be supplied | Construction drawings, technical data sheets, test certificates and calculations to be produced by the contractor. |
| Article 7, testing and partial handovers | Verification protocols, watertightness tests, acoustic measurements, thermal checks. |
Drafting a specification well requires a thorough command of the DTU, the French unified technical codes applicable to each trade. They set the rules of the art for every construction technique, and they are the reference that can be invoked when a dispute arises between contractor and client.
Specifications for the technical packages
For the technical packages, mechanical, plumbing, power, data, smoke extraction and external works, the specifications are drafted by the specialist consultants rather than by the economist. The economist coordinates the whole, checks the specifications hold together, and integrates them into the PRO pack.
- ℹ Structural specification, drafted by the structural consultant. Covers concrete, reinforcement, structural timber and, where relevant, seismic provisions.
- ℹ Mechanical and plumbing specification, drafted by the services consultant. Carries the schematic layouts as annexes, the thermal performance of the plant and the control requirements.
- ℹ Electrical specification, drafted by the electrical consultant. Carries the low-voltage schematic, the required lighting levels and the requirements for the distribution boards.
- ℹ Smoke extraction specification, often integrated into the mechanical document. Describes mechanical or natural extraction according to the applicable public-access building regulations.
PRO quantities and the priced bill
The PRO quantities are the definitive version of the costing document. They list every element of the project with its unit of measure, square metres, linear metres, cubic metres, number or lump sum, and the quantity taken off the PRO drawings. They are the basis of the pricing schedules that contractors will complete with their rates at tender.
PRO quantities, pricing schedule and priced bill
| PRO quantities | The economist's internal working document. Confirms that the costs hold together overall and exposes any gap against the APD commitment. Not necessarily issued to contractors as it stands. |
|---|---|
| DPGF, the pricing schedule | The formatted version of the quantities, issued to contractors in the tender pack. Contractors add their unit rates and totals. It becomes a contractual document on signature. |
| DQE, the priced bill | A schedule of unit rates used on remeasurement contracts, or as a supplementary document. It allows additional and varied works to be priced during construction from the rates in the original contract. |
ℹ The pricing schedule: the financial centre of the works contract The schedule completed by the contractor is the contractual breakdown of its lump sum price. It is not a schedule of binding quantities: on a lump sum contract the quantities are indicative and it is the unit rates that matter. During construction the schedule serves to calculate the monthly interim applications, to value additional works where a rate already exists, and to calculate omissions where work provided for in the contract is removed. A design team without a structured pricing schedule cannot manage a site effectively. That is why the quality of the PRO pack governs the quality of the financial monitoring during construction.
Coordination at PRO: pre-coordination
The PRO stage must anticipate the coordination problems that would otherwise surface on site. The design team runs a pre-coordination exercise, confirming that the main ductwork can pass beneath the beams while leaving adequate height below the ceiling, and that the terminals, diffusers, light fittings, detectors, sit coherently with one another.
Pre-coordination done properly at PRO spares weeks of confusion on site. Coordination problems left unresolved become disputes between contractors, changes during the works, and often variations.
What Quostra takes on at PRO
PRO is the peak of documentary production in the appointment. Drafting complete and precise specifications for a dozen packages, producing the matching quantities, reading the consultants' drawings back to check they agree: that is several weeks of technical work, and it is work the construction economist takes on in full.
ℹ Quostra, the construction economist on demand Cost estimates, pricing schedules, developer appraisals, summary notes. The deliverables that take you days today, taken on by a dedicated economist. You have better things to do. Submit your project and an economist takes over. → quostra.com
Sources: Léonard Hamburger, Maître d'œuvre Bâtiment, 3rd ed., Eyrolles, 2016 · Yves Widloecher and David Cusant, Manuel d'analyse d'un dossier de bâtiment, 2nd ed., Eyrolles, 2018.