The three main blocks
| Block | What it covers |
|---|---|
| Shell | foundations, structure, masonry, roof |
| Second fix | services, insulation, partitions, joinery |
| Finishes | coverings, decoration, equipment |
Luxembourg professional sources place the shell at around a third to four tenths of the works budget, the second fix at a comparable or slightly higher share, and finishes at a smaller but highly variable share.
That variability of finishes is structural. It is the block where specification translates most directly.
What varies each block
The shell varies with form and site. A complex volume, a basement, a slope or particular foundations make it heavier. It depends little on specification.
The second fix varies with technical requirements. The energy standards applying to new construction bear mainly here, through insulation, airtightness and building services.
Finishes vary with specification, within a range that can reach double on that block alone.
Practical consequence: a client seeking to reduce their budget instinctively targets finishes, the most visible block but not the heaviest.
The effect of the energy standard
A specifically Luxembourg point, and it shifts the breakdown. Labour costs weigh more heavily than elsewhere.
The requirements applying to new construction concentrate a significant share of cost in the second fix, insulation, airtightness, ventilation and heat generation.
That share is not a comfort choice. It is a matter of compliance, and therefore not a lever, as the article on why building is expensive here explains.
It also explains why the Luxembourg breakdown differs from that observed in countries with lower requirements, which makes international breakdown comparisons of little use.
The professional use of this breakdown
Three uses, all at an early stage.
Detecting an inconsistency in an offer. An unusually low shell share on a project with a basement, or a low second fix share on a new build, generally signal an incomplete scope.
Directing decisions to the block that weighs. Reducing finishes on a project whose shell is made heavier by its form achieves little.
Structuring an early-stage estimate, before any detailed measurement, covered in the article on building an item-by-item estimate.
Its limits
Two precautions, so as not to treat it as a precision tool. The breakdown varies with the brief and the specification level.
These blocks do not replace measurement. They give a structure, not quantities, and detailed description of works belongs to the guide on measurement and specification.
Proportions vary with the brief. A project with a basement, a refurbishment or a non-residential building show different breakdowns from a new house.
The breakdown serves to check, never to price.
What this means for a professional
Four rules.
Read an offer by main blocks before reading it line by line, which reveals scope inconsistencies faster.
Recall that finishes are not the main block, contrary to the client's intuition.
Explain the regulatory share of the second fix, which is not negotiable.
Do not compare a Luxembourg breakdown with a foreign one, technical requirements differing.
This article reflects the state of the data at the date of checking and serves professional orientation. It does not replace measurement or a detailed estimate.