Question 1

Is the feasibility visit paid?

Accepted Answer

Yes, the feasibility visit is paid. It is fully deducted from the preliminary-studies contract if you sign it afterwards. This allows us to engage in real analytical work rather than a purely commercial appointment. The amount is given to you by phone or in a quote, 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

Two 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), 80% in drawdowns proportional to progress validated in site meetings, and 5% upon signing the handover certificate (PV de réception).

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, art. 1792-6 of the French Civil Code), biennial guarantee (2 years on the proper functioning of separable equipment, art. 1792-3), decennial guarantee (10 years on damage that compromises the solidity of the building or makes it unfit for its purpose, art. 1792 and 1792-2). Structural Damage Insurance (Dommages-Ouvrage) is the compulsory insurance you take out as project owner before works start (art. L. 242-1 of the French Insurance Code). You can take it out directly, or mandate us to take it out in your name.

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 insurance, taken out by you, 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. Elsewhere in France, we work directly or refer you to a member firm of the Les Architecteurs cooperative, of which Xiléades is a member.

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.
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 (new or existing) On quote	On quote	10 – 16 %	On quote

Our offer: Design + Build.

Typologies × missions

Two projects, two budgets.

Timber extension 45 m² — Maisons-Alfort (94)

Veterinary clinic 220 m² — Paris 12th

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