Why a Belgian price per m² is almost never comparable
A price per m² is the result of a division. In Belgium both terms of that division float.
In the denominator, area follows no mandatory definition. This is the Belgian feature with the heaviest consequences. A standard exists, NBN B 06-002, published in June 1983 and taken up in a royal decree of 1984, which defines areas and their measurement precisely. But its application rests on a voluntary basis and it has not been made mandatory for calculating habitable area.
Several methods therefore coexist lawfully. A seller, an architect, a surveyor and an authority may each quote a different area for the same property without any of them being at fault.
In the numerator, the scope of works varies with the stage adopted. Open shell, closed shell, part-finished shell and turnkey do not describe the same work, and the gap between the first and the last represents a major share of total cost.
Both points are developed in the article on what a price per m² covers. They govern every comparison between two quotes.
The Belgian m² is not the French m²
A useful comparison for anyone working on both sides of the border. The two markets do not use the same measurement conventions.
In Belgium the area usually quoted is the gross area, including internal partitions, façade walls and half of party walls. Those elements represent a notable share of total area, in the order of fifteen per cent depending on configuration.
In France the prescribed method excludes them. The gap between the two countries therefore concerns the measured scope, not the price.
For the same property the Belgian figure is therefore higher, and the Belgian benchmark appears mechanically lower although the total price is identical.
The definitions sit in the article on reference areas, which also covers the third definition applying to Brussels projects, whose height threshold differs from the standard's. That third definition does not carry over into a benchmark calculation.
The four completion stages
A preliminary clarification, because Belgian commercial vocabulary sustains a confusion. The same words cover different work scopes depending on the contractor.
"Closed shell" and "weathertight" denote the same stage, not two successive steps. The first describes the scope of works, the second the result achieved.
| Stage | What is delivered |
|---|---|
| Open shell | earthworks, foundations, slab, loadbearing masonry, roof structure |
| Closed shell | adds roof covering, external joinery, weather and air tightness |
| Part-finished shell | adds some services and finishes, scope varies |
| Turnkey | the whole, habitable on delivery |
The part-finished shell has no stable definition and produces most misunderstandings. It requires an explicit list of trades rather than a heading.
On the budget share represented by the closed shell, published sources diverge: between forty and sixty per cent on some accounts, between fifty and seventy on others. That divergence reflects the variable content of the stage and the reference level of finish. Retain that roughly half the budget remains to be spent after the closed shell, and check the split on the actual project.
These stages are developed in the article on completion stages. The stage chosen changes the price per m² considerably.
Ranges by project type
The values below are excluding VAT, excluding land and excluding ancillary costs, expressed on habitable area, and drawn from Belgian professional sources published in 2026. Each of those exclusions must be added back to reach a budget.
New detached house
| Stage | Order of magnitude |
|---|---|
| Open shell | roughly 600 to 1,000 €/m² |
| Closed shell | roughly 800 to 1,500 €/m² |
| Turnkey | roughly 1,400 to 2,500 €/m² |
Some sources quote higher values, in the order of 2,150 to 2,700 euros, or a reference around 2,400 euros. They do not contradict the above: they include VAT and architect's fees.
A conversion: a turnkey house at 1,700 euros excluding tax becomes roughly 2,060 euros including tax after applying the standard rate, and approaches the highest values once fees, studies and connections are added. The gap between the quoted benchmark and the real cost thus exceeds a third.
The detail sits in the article on the new detached house. It gives the ranges by level of finish.
Refurbishment and rebuilding
| Level of intervention | Order of magnitude |
|---|---|
| Redecoration | roughly 300 to 800 €/m² |
| Medium refurbishment | roughly 700 to 1,100 €/m² |
| Major refurbishment | roughly 1,100 to 2,500 €/m² |
| Demolition and rebuild | roughly 1,200 to 2,200 €/m² |
The last two rows overlap, and that is the most important fact in the table. Major refurbishment can cost more than demolition and rebuild, reversing common intuition.
Two mechanisms explain it. The reduced VAT regime for demolition and rebuild became permanent and applicable across Belgium in 2024, under strict conditions. And the uncertainty specific to existing fabric disappears with the building.
The detail and the four situations where refurbishment remains preferable sit in the article on major refurbishment. The choice between refurbishing and rebuilding turns on those four configurations.
Apartment buildings, offices and retail
No range is given for these segments, and that is deliberate. Dispersion depends too heavily on the brief and above all on the denominator adopted.
In collective housing, a benchmark related to private areas alone is mechanically higher than one on constructed area, since the numerator includes circulation and common rooms. In commercial property, two distinct budgets coexist: the shell carried by the owner and the fit-out carried by the occupier.
These segments are covered in the articles on apartment buildings and on offices and retail. Their benchmarks cannot be derived from those of the detached house.
What drives the cost
Once conventions are fixed, the useful distinction is not between large and small factors but between what is decided and what is imposed. That distinction sets the order in which decisions are taken.
Decided: the level of finish, the complexity of form and the performance level beyond the regulatory minimum.
Imposed: the site, regulatory requirements and market conditions.
The consequence is a rule of method: address imposed factors first, since sound decisions are only possible once what cannot be decided is known. Site and region are observed, the level of finish is chosen.
Two points deserve retaining.
The finish effect is multiplicative. A standard finish at around 25 euros per m² and solid oak parquet at around 100 euros produce, on 80 m², a difference in the order of six thousand euros for that item alone. Three or four upgrades compound across different quantities.
Ground investigation is an investment. A few hundred to a little over a thousand euros, against a gap between shallow and deep foundations running into tens of thousands. Carrying out the investigation after buying the land amounts to discovering the price after the purchase.
These factors are developed in the articles on cost drivers, the level of finish and site and siting. The three articles are read in that order.
Three regions, three cost frameworks
In Belgium the region is not a variable to adjust within a budget. It sets the budget's framework. Spatial planning, energy performance and renovation support are regional competences, with three autonomous codes.
Consent periods vary threefold
| Region | Consent period |
|---|---|
| Flanders | 60 days simplified, 105 days ordinary |
| Wallonia | 75 to 115 days depending on procedure |
| Brussels-Capital | 160 days |
These periods run from a complete file, which is not the date of submission. Between a simplified Flemish procedure and a Brussels procedure, the gap exceeds three months of carrying cost, with prolonged professional fees and greater exposure to price movement on top.
The same project may moreover be entirely exempt from consent on one side of the language border and require it on the other. The check is therefore made municipality by municipality rather than nationally.
Energy requirements are not aligned
Even the acronyms differ: PEB in Wallonia and Brussels, EPB in Flanders, without the calculation methods coinciding. A result obtained in one region does not carry over to another.
In Wallonia the Q-ZEN standard has applied to buildings to be constructed since 1 January 2021, with a further requirement since 1 January 2026: at least 35 % renewable energy in annual primary energy consumption, with a sub-condition of 15 % for buildings of 1,000 m² or more. Those thresholds are checked on the regional energy portal before any costing.
Existing stock is becoming a cost factor
This is the most important development of recent years. All three regions now place obligations on existing buildings.
Flanders imposes a renovation duty after acquiring an insufficiently performing property. Wallonia recast its timetable in December 2025 and links rent indexation to the label. Brussels frames the trajectory of its stock through a regional strategy.
One immediate deadline concerns Wallonia: the current grant regime closes to new applications on 30 September 2026, final invoice included. A new regime based on loans and label improvement is due to take over on 1 October, but its terms were only approved at first reading on 16 July 2026.
These three frameworks are covered in the articles on the three regions, Wallonia, Flanders and Brussels. Each region imposes its own regulatory timetable.
From benchmark to budget
A construction benchmark and a client's budget do not measure the same thing. Four gaps separate them.
VAT
The gap between the two applicable rates represents fifteen per cent of the sum excluding tax. On a hundred-thousand-euro project, fifteen thousand euros.
Three distinct regimes coexist: new build at the standard rate, refurbishment at the reduced rate under cumulative conditions, and demolition and rebuild under an autonomous regime. The applicable regime is determined before the quote is drawn up.
The conditions for the reduced rate on refurbishment concern notably the age of the dwelling, measured from first occupation, its use as private housing, the status of the contractor, invoicing to the final consumer and a statement on the invoice. Those conditions are cumulative and a single failure forfeits the reduced rate.
Two recent changes turned a technical decision into a fiscal one. Gas and oil boilers have fallen under the standard rate since 1 July 2025, while heat pumps have qualified for the reduced rate since 1 January 2026 even in a recent dwelling, under a measure announced as temporary.
The detail and the five costliest pitfalls sit in the article on VAT on construction. Those pitfalls surface at audit, years after the works.
Fees, at a different rate
The architect is mandatory in Belgium for works requiring consent, including under turnkey arrangements, with a requirement of independence from the contractor.
And above all: intellectual services fall in principle under the standard rate, even where they prepare works at the reduced rate. On a qualifying refurbishment project the contractor invoices at the reduced rate and the architect at the standard rate. A funding plan applying a single rate is wrong by construction.
Depending on the project, the energy performance officer, the structural engineer, the safety coordinator and sometimes technical control are added. The Act of 31 May 2017 further requires contractors and architects to insure their ten-year liability.
The detail sits in the article on fees and ancillary costs. Those items represent a significant share of the total budget.
Items outside the benchmark
Six families remain outside any construction benchmark: land, studies and control, consents, connections, external works and project charges. None appears in a price per m² and all of them are paid.
Connections are the most underestimated item, because they are invisible at offer stage and depend on third parties whose tariffs and lead times the project does not control.
Those items are listed in the article on what the price does not include. The list serves as a check before a budget is put to a client.
Price revision
More than twelve months often elapse between estimate and execution, the more so where consent takes time. Indexation must therefore be anticipated at the estimate stage.
The ABEX index is the usual Belgian reference for the evolution of construction costs. Established half-yearly, it stands at 1056 for the first half of 2026.
An in-house benchmark kept without its reference index is unusable, exactly like one kept without its area convention.
The mechanism of revision formulas and the trade-off between fixed and revisable price are covered in the article on price revision. The choice between the two formulas allocates the risk between the parties.
The method, in summary
Seven steps, in this order.
1. Name the region and the municipality. They determine requirements, periods and support.
2. Determine the applicable VAT regime, with its conditions.
3. Fix the three conventions: reference area and measurement method, completion stage with list of trades, excluded items.
4. Price the land separately and first, because it determines whether the brief is achievable.
5. Use the benchmark to check, not to price. A benchmark confirms that a brief fits an envelope; it does not replace measurement.
6. Add excluded items and fees, applying to each its own VAT rate.
7. Provide for revision and contingency, in proportion to duration and the share of existing fabric. Ten to fifteen per cent is common on new build, more wherever existing fabric is involved.
To compare two offers, the six-step normalisation method sits in the article on comparing two quotes.
A point about liability
The absence of a mandatory definition of area is not merely a methodological inconvenience. It carries consequences in professional liability.
Belgian case law has held a property professional liable for using the notion of habitable area in a context where it could denote sometimes a gross and sometimes a net area. The court observed that they could simply have written "gross area".
Naming the convention used costs three words and avoids a dispute.
This guide reflects professional practice, standards and regulation at the date of checking and serves as orientation. It does not constitute legal or tax advice and does not replace assessment of the individual case.