What is the difference between a general contractor and a general builder?

A general builder carries out works, all trades, on the basis of a design that is supplied to it or that it has produced. A general contractor commits to a delivered building, design included, at an agreed price and date: its contract covers the result, not only the works. In practice, the general contractor integrates design and coordination into its commitment.

Is an architect required in Design + Build?

Yes, in almost every case. Using an architect is mandatory for a legal entity's building permit, and for a private individual above 150 m² of floor area (French Planning Code, art. R*431-2). Beyond the obligation, design is what creates the use value and the future value of the building. At Xiléades, the design is signed by an architect in the team assembled by the general contractor.

Who carries the insurance?

Xiléades Architecteurs holds professional liability insurance, the ten-year structural guarantee and all-risks site insurance. Building damage insurance (dommages-ouvrage) is the client's: you take it out before the site opens, directly or by mandating us to do so in your name. The completion, two-year and ten-year guarantees apply from handover, as for any building.

Can I impose a contractor I know?

You can propose one to us. We consult it like the others, and if it meets the specification and accepts our site conditions, it can be selected. But it is the general contractor that contracts with it and answers for its work to you: we cannot commit to a price and a deadline with a company we did not choose.

What happens if the site costs more than planned?

If the extra cost comes from a design error or a coordination failure, it is ours: that is the meaning of the firm global price. If it comes from a change you request or from a condition the studies could not reveal, it is handled by a priced amendment that you accept before execution. The contract also provides for indexation on the BT01 index between signature and site start; it is written, it is not decided along the way.

Does Design + Build cost more than classic architect-led procurement?

Design and management fees are integrated into the global price instead of being invoiced separately: the total to compare is the cost of the delivered building, not the 'fees' line. What the arrangement brings is a price known before the works start and carried by a single responsible party. We publish representative ranges on our Pricing page; the price of your project is built during the studies.

And for a public contract?

Public design-and-build is a specific type of contract, allowed in limited cases by the Public Procurement Code. Outside those cases, the buyer awards a design contract and then works contracts. Xiléades responds to calls for tender in either framework, in a consortium with a co-contracting architect when the design has to be carried separately.

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Reference page

Design + Build:
one contract, from study to keys.

Design + Build, also called design-and-build, entrusts the design of your project and its construction to the same partner. At Xiléades Architecteurs, a general contractor and member of the Les Architecteurs network, that partner commits by contract to a firm global price and to a delivery date. This page explains what that changes, who it is for, and when it is not the right choice.

Definition

Three terms for one idea

In a building or fit-out project, two trades usually follow one another: the one that designs, the architect and the engineering consultants, and those that build, the contractors of each trade. The client signs a contract with each of them and carries the coordination between them.

Design + Build brings these two trades under a single contractual responsibility. The client has one contact, one price, one deadline. The design is still signed by an architect, because the law requires it for most planning permits and because that is what makes the quality of the project; the construction is carried by the general contractor, who selects, contracts and coordinates the trades.

Three expressions describe this arrangement depending on the context. They are not quite synonyms.

Design + Build: The English expression, now common in France for private projects. It stresses the continuity between drawing and site: the same team carries the project from sketch to handover.
Design-and-build (conception-réalisation): The French term, which also has a precise meaning in public procurement: a single contract for design and works, governed by the Public Procurement Code (art. L. 2171-2) and reserved for defined cases. In private contracts, the expression simply describes the same arrangement, without those restrictions.
General contractor (contractant général): The party that signs the single contract with the client and commits to the scope, price and deadline of the delivered building. It subcontracts or co-contracts the trades but remains solely responsible to its client. This is the status of Xiléades Architecteurs.

Comparison

Architect-led procurement, general builder or Design + Build

Three ways to contract for the same building. None is bad in itself: each distributes work, risk and responsibility differently.

Criterion	Classic architect-led procurementArchitect on one side, contractors on the other	General builder aloneWorks without a dedicated architect	Design + BuildXiléades, general contractor
Who designs	The architect, under contract with you.	The builder's design office, or nobody.	An architect, in the design team assembled by the general contractor.
Who builds	Trade contractors, each under contract with you.	The general builder and its subcontractors.	The general contractor and the companies it contracts.
Number of contracts you sign	One per party: often five to fifteen.	One, sometimes preceded by a separate design contract.	A study contract, then a construction contract.
Who carries the price	You: the architect's estimate does not bind the contractors.	The builder, on a specification it has often written itself.	The general contractor: firm global price when the construction contract is signed.
Who carries the deadline	Each contractor for its trade; one delay shifts the others.	The builder, for the works part.	The general contractor, from the end of studies to handover.
Coordination of trades	The architect's task, by delegation; the contractors remain your counterparties.	Internal to the builder.	Internal to the general contractor, which answers for it to you.
When something goes wrong	It has to be established whether the designer or the builder answers for it.	The builder, within the limits of what it designed.	A single responsible party: the general contractor, design and execution included.
When it is the right choice	You want to tender the contractors yourself and keep control of each contract.	Simple works, with no design or permit at stake.	You want an opening date that holds, a budget known before you start, and a single contact.

Who designs

Classic architect-led procurement: The architect, under contract with you.
General builder alone: The builder's design office, or nobody.
Design + Build: An architect, in the design team assembled by the general contractor.

Who builds

Classic architect-led procurement: Trade contractors, each under contract with you.
General builder alone: The general builder and its subcontractors.
Design + Build: The general contractor and the companies it contracts.

Number of contracts you sign

Classic architect-led procurement: One per party: often five to fifteen.
General builder alone: One, sometimes preceded by a separate design contract.
Design + Build: A study contract, then a construction contract.

Who carries the price

Classic architect-led procurement: You: the architect's estimate does not bind the contractors.
General builder alone: The builder, on a specification it has often written itself.
Design + Build: The general contractor: firm global price when the construction contract is signed.

Who carries the deadline

Classic architect-led procurement: Each contractor for its trade; one delay shifts the others.
General builder alone: The builder, for the works part.
Design + Build: The general contractor, from the end of studies to handover.

Coordination of trades

Classic architect-led procurement: The architect's task, by delegation; the contractors remain your counterparties.
General builder alone: Internal to the builder.
Design + Build: Internal to the general contractor, which answers for it to you.

When something goes wrong

Classic architect-led procurement: It has to be established whether the designer or the builder answers for it.
General builder alone: The builder, within the limits of what it designed.
Design + Build: A single responsible party: the general contractor, design and execution included.

When it is the right choice

Classic architect-led procurement: You want to tender the contractors yourself and keep control of each contract.
General builder alone: Simple works, with no design or permit at stake.
Design + Build: You want an opening date that holds, a budget known before you start, and a single contact.

Classic architect-led procurement remains the market reference, and it is the one we show for comparison on our Pricing page. Xiléades does not sell it: we work in Design + Build. Our ranges by building type

At Xiléades

Three milestones, three contracts, a progressive commitment

We do not commit to a price on an idea. The firm global price is signed once the project is drawn, priced by trade and authorised. Before that, each stage has its own contract, and you can stop at any of them.

01
The feasibility visit
A first on-site meeting, paid for, which funds real analysis work: programme, constraints of the building and of planning rules, a first order of magnitude for the budget. Its amount is given to you by quotation and is deducted from the study contract if you go further.
02
The preliminary study contract
Detailed feasibility, outline then detailed design, shared BIM model, permit application. At the end of these studies we know the project precisely enough to commit to its price.
03
The construction contract
The contract that commits the firm global price and the delivery date. It relies on the standard contracts that the Les Architecteurs cooperative provides to its members. The price then changes only by an amendment signed by you, or through the indexation mechanisms written in the contract.

See the method step by step What our guarantees cover

Who it is for

The projects where Design + Build changes the outcome

The arrangement makes most sense when the opening date, business continuity or budget control weigh as much as the architecture. That is the case for most professional projects, and for some private ones.

Xiléades Architecteurs works in Paris and the Île-de-France region. Beyond, we design the project and site supervision goes to a member of the Les Architecteurs network based near you.

Design + Build is not our only trade: we also carry out technical studies and preliminary studies as a service, site supervision, and the BIM structuring of a building portfolio's data.

The limits

When Design + Build is not the right choice

An arrangement that promises everything to everyone is not serious. Here are the cases where we advise something else, or where we set conditions.

You want to tender the contractors yourself

That is legitimate, and it is the essence of classic architect-led procurement. In Design + Build, the general contractor consults and selects the contractors, because it answers for their work. You may ask to know which companies were selected; you do not choose them in our place.

The programme is not settled

A firm price is signed on a defined project. As long as surfaces, uses or the level of finish are moving, we stay under a study contract. Signing a global price on a vague programme protects nobody well.

You are a public buyer

In public procurement, design-and-build is a separate type of contract, reserved for cases defined by the Public Procurement Code. Outside those cases, design and works must be separated, and we then respond in that framework, in a consortium with a co-contracting architect.

The project is very small

For work with no design and no permit, a single builder does the job and costs less. Design + Build is justified when there is something to design, to authorise and to coordinate.

A firm price is not a price without amendments

The committed price covers what the studies made visible. A change you request, or a genuinely unforeseeable condition discovered during demolition, gives rise to a priced amendment accepted before execution. The difference from other arrangements is that these cases are written into the contract in advance, with their mechanism.

Frequently asked questions

What clients ask us

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Design + Build:one contract, from study to keys.