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New detached house

📐 Article6 min read

What you will learn Ranges by stage with their conventions stated, why sources diverge so widely, the effect of construction method, and how to move from benchmark to total budget.

The new detached house is the best-documented project type in Belgium, and paradoxically the one where published figures conflict most. The scope each source uses explains those contradictions.

Ranges by stage

The values below are excluding VAT, excluding land and excluding ancillary costs, expressed on habitable area. Each of those exclusions must be added back to reach a budget.

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

These ranges come from Belgian professional sources published in 2026. They are wide, and their width is itself information.

Some sources quote considerably higher values, in the order of 2,150 to 2,700 euros per m², or a reference around 2,400 euros. Those figures are not inconsistent with the above: they include VAT and architect's fees.

How the sources reconcile

A conversion shows the mechanism.

A turnkey house quoted at 1,700 euros per m² excluding tax becomes, after applying 21 % VAT on new build, roughly 2,060 euros per m² including tax. Adding fees, studies and connections approaches the higher published values.

The sources therefore do not contradict one another; they answer different questions. A builder quotes what it invoices, a portal quotes what the project costs.

An illustration from the market: a turnkey model of 180 m² habitable representing roughly 300,000 euros excluding tax, close to 363,000 euros including tax, to which architect's fees, kitchen and connections are added. The gap between the advertised price and the final budget thus exceeds a quarter.

Construction method shifts the distribution

The choice between traditional construction and industrialised timber frame changes the distribution of cost as much as its level. The two systems therefore do not compare on the benchmark alone.

Prefabricated timber frame reaches the weathertight stage faster, reducing exposure to weather and construction duration, and therefore carrying cost. That time saving translates directly into finance charges avoided.

Against that, the share of structure in the total differs, and ranges quoted by timber builders span very widely by formula, from self-assembly kit to complete turnkey. The formula chosen must therefore be stated before any comparison.

Comparing a timber benchmark with a traditional one without stating the formula is meaningless.

Land is not in the benchmark

A structuring reminder, because this item often decides feasibility. It is the land, absent from any construction benchmark.

Land prices vary sharply: in the order of 50 to 150 euros per m² in the provinces, and markedly more in pressured areas, where they can exceed 300 euros per m² in Walloon Brabant or the Brussels periphery. Those values are checked municipality by municipality rather than by region.

On a typical project, land can represent a share comparable to a quarter or a third of the total budget. Registration duties and deed costs are added.

A recent phenomenon deserves attention: in sought-after areas, the main difficulty is no longer financing the build but finding a building plot. Land scarcity thus shifts the constraint from budget to availability.

From benchmark to total budget

An order of magnitude for a complete budget, for a family house of about 150 m² on 2026 sources, breaks down as follows. It serves as a reference point and not as a costing for a given project.

Item Order of magnitude
Construction per benchmark and stage adopted
Land highly variable by location
Studies, connections, coordination roughly 8,000 to 15,000 €
External works roughly 15,000 to 20,000 €
Kitchen and equipment roughly 20,000 to 30,000 €
Contingency 10 to 15 % of construction cost

Sources consulted place the total budget of such a project, land included, in a wide band depending above all on land value. Land accounts for most of the spread observed.

The contingency is not an optional precaution. A provision of ten to fifteen per cent is common professional practice on new build, and more wherever existing fabric is involved.

What varies at equal brief

Four levers dominate, in decreasing order of impact. The first three follow from a decision, the last is observed.

The level of finish, the most powerful lever after the stage itself.

The complexity of form, setbacks, levels, multiple roof planes, which increases lengths without increasing area.

The site, its slope, its ground and its accessibility.

The energy performance level targeted, beyond the regulatory minimum applicable in the region.

What this means for an estimate

Three rules.

Always state the triplet stage, area, VAT alongside a benchmark, or it will be misread.

Do not transpose a benchmark from one area to another without correcting for the scale effect.

Price the land separately and first, because it determines whether the brief is achievable.

This article reflects professional practice and observed prices at the date of checking and serves as orientation. It does not constitute legal advice and does not replace assessment of the individual case.

Frequently asked questions

The ranges are read excluding VAT, land and ancillary costs, on habitable area, and vary sharply with the stage and level of finish.

Not necessarily. It reaches weathertight faster, shortening the carrying period, but formulas run from self-assembly kits to full turnkey.

In the order of 50 to 150 euros per m² in the provinces, and markedly more in pressured areas, where it can exceed 300 euros per m².

The level of finish, the geometry of the scheme, the size and finally the region, in decreasing order of impact.

Construction costs per m² in Belgium: a guide by region