Construction economics: the complete guide for professionals

Construction economics covers the disciplines that allow the financial resources of a building or infrastructure project to be planned, priced, controlled and optimised. It articulates three fundamental dimensions: the technical, what is to be built; time, to what programme; and money, with what means.

Unlike general economics, construction economics applies to products that are unique, located and durable. Every project is a prototype: even similar buildings will cost differently according to their siting, the ground conditions, local regulatory constraints or the tension in the materials market at the moment of tender.

The architect is often the client's principal interlocutor on economic questions. They are the first to warn of an overrun risk, to propose cheaper variants, or to justify a higher investment by a long-term gain in value. Insufficient command of construction economics exposes the architect to disputes, to reduced fees or, worse, to the questioning of their scheme mid-construction.

The cost of a construction project is not simply the cost of the works. It covers a set of expenses that must be identified and anticipated from the earliest studies.

The all-in cost is the most complete view. It brings together four families of expenditure:

• The works cost: structure, finishing trades, external works, technical equipment. The most visible part and the most variable with location.
• Design fees: architect, structural and services engineers, economist, health and safety coordinator, technical controller.
• Land costs: acquiring the site, legal fees, development taxes.
• Finance costs: interest during construction, bank guarantees, insurance.

Indicative orders of magnitude for France For a standard residential building in a dense urban area, the works cost generally represents 60 to 70 % of the total, fees 8 to 12 %, and land and finance costs the remaining 20 to 30 %. These ratios vary significantly with the type of project, the location and market conditions.

Several factors bear directly on the level of a project's costs. Knowing them allows the risks to be anticipated and the settings adjusted from the design stage.

Understanding how a contractor builds its selling price is essential to analysing an offer, detecting an abnormally low bid or negotiating a variation. The fundamental equation of the price excluding VAT is:

Price = net cost + site overheads + operation costs + head office overheads + risk and profit Or, multiplicatively: price = a coefficient × the net cost

That mechanism explains why an apparently low offer can conceal an insufficient risk allowance, a source of claims and variations during construction. It also explains why aggressive price negotiation can weaken the contractor and, ultimately, the quality of the work.

To go further: How to estimate the cost of a construction project · Cost per square metre by building type

Every construction project must identify and secure its funding sources before the planning application is even filed. That step directly governs the feasibility of the operation.

• Equity: the operator's own or corporate contribution. The larger it is, the better the borrowing terms.
• Bank credit: a classic mortgage for private individuals, a development loan for professionals. The latter is structured specifically to cover the duration of a development.
• Public grants and support: national housing agency funds, regional support, state equipment grants, European funds, according to the project and its location.
• Crowdfunding: growing strongly since 2015, it raises funds from private investors alongside bank finance.

The optimal structure depends on the operator's profile, the type of project, housing, offices, public facility, and the level of pre-sales achieved when finance is sought. A developer presenting 40 % of off-plan sales signed will obtain significantly better terms than a project with no pre-sales.

To go further: Property financing options · Construction grants and subsidies

In construction, a contract binds the client to a provider, a contractor, a design team, an engineer. The nature of the client, public or private, determines which rules apply.

Public contracts are subject to the public procurement code, which imposes rigorous competitive procedures above certain thresholds. The objective is to guarantee equal treatment of candidates, transparency and the efficient use of public money.

Three procedures are principally distinguished: the open tender, where any candidate may bid; the restricted tender, where only pre-selected candidates receive the documents; and the negotiated procedure, used notably for design appointments.

In the private sector the client is free to choose providers without any formal competitive obligation. In practice most operations of any size are put out to several contractors to obtain comparable offers and optimise the price. The relationship is governed by the civil code and by the standard conditions of contract used in private work.

To go further: How a construction tender works · Writing the specification and the conditions of contract

A construction project is not judged solely on its architectural or technical quality. For investors, developers and professional clients, the financial return of the operation is a central decision criterion.

The return on a project is sensitive to several parameters at once: the level of construction costs, the local market sale or rental price, the cost of finance and the duration of delivery. A six-month extension to the programme can be enough to turn a profitable operation into a loss-making one.

After every site, a contractor produces an analytical account of the operation. That mechanism is little known to architects, but it directly explains the behaviour they observe on site.

For the design team, understanding this mechanism makes site behaviour legible: a contractor short of its risk allowance tends to multiply claims and variation requests to restore its result. A contractor forced to negotiate too low may sacrifice quality of execution to reduce costs. Mastering this mechanism is one of the most effective tools for preventing site conflict.

To go further: How to calculate the return on a construction project

Construction mobilises an ecosystem of parties with distinct roles and responsibilities. Understanding who intervenes, when, and with what powers is indispensable to navigating a complex project.

• The client: the promoter of the project and the decision-maker. They define the brief, fund the operation and bear final responsibility.
• The client's adviser: counsel on technical, legal and financial matters. Particularly useful for clients who are not construction professionals.

• The architect: designer of the scheme, often lead consultant of the design team. They coordinate the other consultants.
• The engineering consultancies: specialists in structure, services, thermal performance, acoustics and so on.
• The construction economist: prices the project, writes the contract documents and monitors the finances during construction. A key role in cost control.

• The contractors: a main contractor or separate trade packages according to the procurement route chosen. That choice bears directly on costs and responsibilities.
• The site coordinator: organises and programmes the interventions of the various contractors on site.

To go further: the construction economist's missions and tools · main contractor against separate packages: what effect on cost?

Construction economics is a cross-cutting discipline that governs the success of every project. It rests on a logical chain: estimate costs well from the design stage, choose the right financing structure, master the procurement rules, analyse the return and rely on the right parties at each step.

The good news is that these skills can be learned, and that they can today be substantially supported by tools that save time without sacrificing the quality of the analysis.

Quostra, the construction economist on demand

Cost estimates, pricing schedules, development 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

ℹ The nature of the figures The orders of magnitude on this page are expressed as percentages of a total, not as amounts. They therefore do not drift with the building cost index and need no updating: it is the distribution that is the reference, not the level. The amounts those percentages apply to must be taken at the date of the study. To bring them forward, use the BT01 all-trades index published monthly by INSEE on its 2010 base, which stood at 134.7 in January 2026.

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.