What each formula covers
A weathertight shell means a building closed and roofed. Structure, roof, façade and external joinery are complete; the interior is not.
Turnkey means a building habitable on handover. Services, partitions, finishes and sanitary fittings are added.
Luxembourg professional sources place the shell in the order of around €1,600 to €2,100 per square metre, and turnkey in a markedly higher range, covered in the article on works cost per m².
The gap between the two corresponds to the whole of the second fix and finishes, which represents a majority share of the works budget.
| Formula | What it covers | What stays with the client |
|---|---|---|
| Weathertight shell | Structure, roof, external joinery | Fit-out, finishes, external works |
| Turnkey | A habitable building | External works, connections, taxes, fees |
The vocabulary is not normative
An essential point, and it applies to both formulas. The exact scope is read in the quotation, not in the label.
No regulatory definition fixes the content of these labels. Two firms may use the same term for different scopes.
Common variants are numerous, notably around kitchen equipment, floor finishes and external works.
The consequence is direct: comparing two offers on the label alone is meaningless. Only the specification counts.
What turnkey never includes
Four items are generally excluded, and forgetting them produces the commonest budget gaps. They concern external works, connections, taxes and fees.
Land and its servicing, covered in the corresponding branch.
Ancillary costs, fees, formalities and connections, covered in the article on ancillary costs and their weight.
External works, terrace, access, boundaries and planting, whose amount can be significant.
Part of the equipment, depending on the contract, notably the kitchen and certain appliances.
A budget built on a turnkey price alone is therefore structurally incomplete, often by a double-digit proportion.
Choosing between the two
It does not reduce to a question of price. The choice between the two formulas also commits the coordination effort.
A shell contract assumes the client takes on what follows, directly or through other firms. That requires time, coordination capability and technical judgment.
Turnkey transfers that burden to the contractor, with the corresponding margin, but also with a single counterpart if a defect arises.
The apparent saving of a shell contract is paid in time and coordination risk, which an occasional client does not always anticipate.
The contractual consequences of the arrangement chosen belong to the guide on working in Luxembourg.
How to check a scope
Four checks, on every quotation before comparison. They cover the scope, the stage, the exclusions and the revision.
Read the specification, not the label. It is the only reliable basis.
Spot the express exclusions, generally at the end of the document and rarely read.
Identify items absent without being excluded, the most dangerous because nothing flags them.
Check the reference area, a price per square metre meaning nothing without it.
The fourth check is the most often skipped, although it alone may explain a large gap between two offers.
What this means for a professional
Four rules.
Never compare offers on the basis of the label, which has no normative content.
Establish a common list of items before inviting offers, the only way to obtain comparable proposals.
Tell the client explicitly what a turnkey price does not include, the gap with the real budget being large.
Quantify the coordination burden where a shell arrangement is considered, rather than presenting it as a net saving.
This article reflects data and practice at the date of checking and serves professional orientation. It does not replace a quotation or examination of the specification.