What a price per m² covers in Belgium

Before comparing two prices, three questions must be answered explicitly. They concern the area, the completion stage and the scope of items included.

Question	What it determines
Which area in the denominator	gross, net or habitable, with or without walls
Which completion stage in the numerator	from weathertight shell to turnkey
Which items are excluded	land, connections, fees, taxes, external works

Without those three answers, a thirty per cent gap between two offers may be entirely conventional. Two contractors can offer exactly the same house at the same total price and show markedly different benchmarks.

This is the Belgian feature with the heaviest consequences, and it often surprises practitioners from other markets. No measurement method is imposed for the sale of dwellings.

A standard exists: NBN B 06-002, published in June 1983, defines the areas and volumes of buildings and how they are measured. It was the subject of a royal decree in 1984.

But its application rests on a voluntary basis. Belgian standards form a reference system; they bind only where a regulation makes them mandatory. That has not been done for calculating habitable area.

The consequence is direct: several methods coexist lawfully, and the same property can be advertised with different areas depending on who measures. The method used must therefore be stated every time.

Definitions and their differences are covered in the article on reference areas. It also gives the Brussels regulatory definition.

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: it includes internal partitions, façade walls and half of party walls. In France the law imposes a method excluding these elements.

For the same property the Belgian figure is therefore higher than the French one, walls and partitions representing a significant share of total area.

A Belgian and a French price per m² therefore do not compare directly, even at identical specification. The Belgian benchmark appears lower simply because its denominator is larger.

The second term of the division varies just as much, and Belgian vocabulary distinguishes stages covering different works. The stage belongs in the quote alongside the price.

A price quoted for a weathertight shell and one quoted turnkey do not describe the same work. The gap between them represents a major share of total cost and is anything but a marginal extra.

These stages are covered in the article on completion stages. The gap between closed shell and turnkey is considerable.

Whatever stage is chosen, a construction price per m² never includes certain items. They do not fall to the contractor and are nonetheless borne by the client.

Land, utility connections, professional fees, taxes and charges, mandatory studies and external works all belong to that category. None of those items sits inside a construction benchmark.

A budget built from a single benchmark per m² is systematically understated, and the gap is not marginal. The detail sits in the article on what the price does not include.

The absence of a mandatory definition is not merely a methodological inconvenience. It carries consequences in professional liability.

Belgian case law has dealt with disputes over the ambiguous use of the notion of habitable area in property transactions, and professionals have been held liable for using a term capable of denoting sometimes a gross and sometimes a net area. Stating the measurement method is therefore a contractual precaution.

For a professional, naming the convention used is therefore not a refinement but a precaution. Writing "gross area" rather than "habitable area" removes the ambiguity at negligible cost.

Four statements are enough to make a benchmark usable. They fit on one line and change everything.

1. The area used and how it was measured, naming the convention rather than assuming it.
2. The completion stage, with the list of trades included.
3. The excluded items, expressly listed.
4. The date and the region, because prices move and requirements differ.

A benchmark carrying those four statements is comparable. One without them is not, however reputable its source.

The article on reference areas covers the definitions, the standard and the differences they produce. It also gives the third definition, specific to Brussels projects.

The article on completion stages covers the shell, weathertight and turnkey stages. It states what each stage covers and what is left to the client.

The article on what the price does not include lists the systematically excluded items. It serves as a check before a budget is presented.