How developed-design quantities are organised by work package

Breaking the measure down by trade is not an arbitrary convention; it reflects the real structure of the construction market. Each trade corresponds to a contractor speciality: the mason, the carpenter, the plumber and the electrician have neither the same skills, nor the same teams, nor the same prices. Organising the measure on that logic achieves two essential things.

First, it prepares the structure of the future tender package directly: each trade in the measure becomes a package in the tender documents, with its own specification and its own pricing schedule. Continuity from developed design to tender is thereby guaranteed without restructuring the document.

Second, it allows a budget reading by responsibility: architect and client can see at once which trade carries most weight, where the trade-offs are concentrated, and which packages have been prioritised for negotiation.

The table below sets out the standard organisation of a developed-design measure for a new-build project in France, with the principal items of each trade and their average budget weight.

Note: the budget weights are indicative for standard new-build apartments. They vary significantly with the building type — public buildings, offices, refurbishment — and with the level of specification. On refurbishment the façade and insulation package can reach 20 to 25 % of the total.

Within each trade, the measure is organised in several hierarchical levels. This tree structure allows reading at different degrees of precision, from the package total down to the elementary item, and anticipates the structure of the specification that will be written at the detailed design stage.

At developed design the measure generally descends to level 3, the elementary item, with a description sufficient to measure the quantities and apply a representative unit rate. Level 4, the price build-up, is reserved for the tender stage, where every element must be described with contractual precision.

ℹ Developed design or tender: how deep does each go? At developed design one writes: "Reinforced concrete strip footings 300 × 600, 85 linear m, 420 €/linear m, 35,700 €". At tender, in the specification and pricing schedule, one adds: C25/30 concrete, reinforcement from 8 to 16 mm, permanent formwork of a stated type, reinforcement to the engineer's drawings, minimum bearing capacity 200 kPa, the price revision formula, and so on. Developed design gives the volume and the cost. The tender documents give the qualitative and contractual requirements.

For some trades the economist can choose to group work into a single package or split it into distinct ones. External joinery, for instance, can be grouped with the façades into an "external envelope" package, or separated in two, according to the size of the project and the tendering strategy.

The choice has direct consequences for competition at tender: too broad a package shuts out local craftsmen, too small a one lacks the critical mass to attract specialist contractors. The economist must judge according to the size of the project and the local contractor base.

Some packages share close technical interfaces that require precise organisation in the measure. The main ones are:

• Structure and mechanical services: the openings in concrete floors and walls for services to pass through must be coordinated between the structural and services engineers. A measure that ignores these interfaces systematically under-values the structural package.
• Mechanical services and electrics: power supply to the mechanical plant, controls and building management sit on the boundary between the two packages. Where that boundary lies must be explicit from developed design onward.
• External joinery and façades: installing the windows, the reveal linings and the vapour barriers are frequent sources of dispute if the boundary of each package is not clearly defined.

Some items affect several trades and must be allocated to one of them coherently and with the allocation documented. This applies to site set-up — generally with the structural package, or as a separate package on larger projects — temporary protection, final cleaning, and testing and inspection.

ℹ A frequent error Leaving cross-cutting items out of the measure on the assumption that they will be distributed between packages at tender. With no explicit rule, each contractor tends to exclude them from its offer, and they reappear as variations. The rule: every item must be allocated to a specific package in the measure, even if its exact definition will be refined at tender.

Each section opens with a reminder of the calculation assumptions specific to that trade: the drawings used, the sizing assumptions adopted in the absence of structural drawings, the level of specification taken. That transparency is indispensable if the document is to be reviewed critically and updated as the project evolves.

The document closes with a general summary bringing together the amount of each trade, the global contingency and the project total excluding VAT. It is this summary page that goes to the client to approve the budget envelope before the detailed design and tender stage is launched.

A developed-design measure is delivered in Excel, so that quantities or unit rates can be updated, and in PDF for reading and archiving. Word is reserved for accompanying notes. The economist can also deliver in the format of a commercial price database if the client wants continuity with their own control tools.

Quostra produces measures structured on the logic described here, adapted to each project type. The document is delivered as a structured Excel workbook with one tab per trade and a summary tab, the assumptions documented in each section and a general summary on the front page.

That structure is directly reusable as the basis of the tender package: trades become packages, items become the articles of the specification and the lines of the pricing schedule, with no wholesale restructuring.

You have better things to do. Submit your project on quostra.com and an economist structures and produces your developed-design measure within 72 working hours.

A well-structured developed-design measure is organised by trade, broken down into families of works and then into elementary items, with explicit assumptions and a summary. That organisation is not a formality: it prepares the structure of the tender package directly, makes technical trade-offs easier, and guarantees that every item is allocated to a specific package with no contractual grey area. It is the foundation of rigorous pricing and of a tender without surprises.