Question 1

Is the feasibility visit free?

Accepted Answer

Yes, a symbolic contribution is requested for the feasibility visit — it corresponds to approximately one hour of Architecteur's time and is fully deducted from your fees if you sign the mission. This allows us to engage in real analytical work rather than a purely commercial appointment. The exact amount and conditions (B2C, small B2B projects, large projects) are specified during the first phone call, depending on your project.

Question 2

Why is there no fixed price displayed?

Accepted Answer

Every project is unique: surface area, building condition, level of finish, urban constraints. We publish representative ranges observed on our recent projects and commit to a firm price at the end of preliminary studies (equivalent to end of APD as a market benchmark), formalized by an Architecteurs type production contract.

Question 3

Does the Design + Build price really include everything?

Accepted Answer

Yes, design and management fees are integrated into the price per m². The package covers design, execution, contractor coordination, mandatory insurance, and decennial guarantee. The only items to be paid separately are those listed in the 'not included' section.

Question 4

What is the payment schedule?

Accepted Answer

Three cases depending on the signed contract. Preliminary study / design: 50% upon signing, balance upon delivery of the file (or 25% / 25% if two missions, 20% / 15% / 15% if three missions). Design + Build execution (Architecteurs type contracts): 5% upon signing, 10% upon fulfillment of conditions precedent (permits, financing, performance bond), 80% in drawdowns proportional to progress validated in site meetings, and 5% upon signing the handover certificate (PV de réception). Single-family house (CCMI): strict schedule provided by article L. 231-2 of the Construction and Housing Code (5% deposit, then 15 / 25 / 40 / 60 / 95 / 100% throughout the stages), with delivery guarantee at the agreed price and deadline.

Question 5

Can the price change during construction?

Accepted Answer

Only within the framework provided by the contract. Two mechanisms govern price changes: index-linking between signing and start of work, and revision at each drawdown, both indexed to the national BT01 index. A 2% franchise absorbs micro-variations; beyond +10%, parties meet to renegotiate. Without a signed clause, the price remains firm. Any modification to the program is subject to a costed amendment accepted before execution.

Question 6

What if a major unpredictable issue arises on site?

Accepted Answer

The Design + Build package includes everything we can reasonably anticipate during the studies. However, a truly unpredictable major issue — structural pathology discovered after stripping, faulty soil or foundations, undetected networks, asbestos outside the diagnostic report, disorders revealed by removal — falls by nature outside the package and is subject to a costed amendment, shared with you before any execution. We document the issue, its origin, and the price/deadline impact. This is the trade-off for a firm price commitment: we can only commit to what has been studied.

Question 7

What guarantees are you required to provide?

Accepted Answer

Perfect completion guarantee (1 year), biennial guarantee (2 years on separable equipment), decennial guarantee (10 years on the structure and inseparable elements). Depending on the contract type: delivery guarantee at agreed price and deadlines for CCMI, performance bond for production contracts exceeding 400,000 € HT or 6 months of construction. Structural Damage Insurance (Dommages-Ouvrage) can be taken out directly by you, or you can mandate us to take it out on your behalf.

Question 8

Are there hidden costs?

Accepted Answer

No. Our quote details every item and systematically lists what is not covered (G1/G2 geotechnical studies, inspection body, SPS coordination, Dommages-Ouvrage if not mandated, development taxes, utility connections). Any evolution of the program is subject to a signed and costed amendment: no additional billing can occur without your written agreement.

Question 9

How does the first meeting work?

Accepted Answer

A free 45-minute appointment, on-site or via video call. We discuss your program, constraints, and target budget. You leave with an indicative range, a mission schedule, and the terms of the feasibility visit if you wish to proceed further.

Question 10

Do you work outside of Paris?

Accepted Answer

Our core business covers Île-de-France. We operate elsewhere in France via the Architecteurs network (50+ partner agencies), which guarantees a local contact.

Typology	Design + Build Most requested Design + construction, single point of contact, committed price and deadline.	MOE — reference Traditional Project Management (Loi MOP). Provided for comparison, not sold by Xiléades.	Design — reference Sketch, APS, APD. Provided for comparison, not sold by Xiléades.
New single-family house € excl. VAT / m² living area	2,200 – 3,200 €	10 – 14 %	180 – 280 €
Extension / Loft conversion € excl. VAT / m² created	2,600 – 3,800 €	11 – 15 %	200 – 320 €
Heavy renovation % of works cost	1,800 – 3,200 € / m²	12 – 16 %	5 – 8 %
Light renovation % of works cost	900 – 1,800 € / m²	10 – 14 %	4 – 7 %
Commercial / ERP On quote	On quote	10 – 16 %	On quote

Our offer: Design + Build.

Typologies × missions

Three projects, three budgets.

New house 150 m² — Vincennes (94)

Timber extension 45 m² — Maisons-Alfort (94)

Veterinary clinic 220 m² — Paris 12th

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