The VMSW specification and BBW 2025, explained
By the ArchiMind teamUpdated on
One text, two names
Flanders has its own standard specification for buildings. Its official name is Bouwtechnisch Bestek Woningbouw, shortened to BBW. The official Flemish page calls it the model specification of Wonen in Vlaanderen: it is the basis for the special specifications of social housing projects.
In practice almost everyone still calls it the VMSW bestek. That name comes from the Vlaamse Maatschappij voor Sociaal Wonen, which published the text for years. In 2023 the staff and part of the duties of the VMSW moved to Wonen in Vlaanderen, while the VMSW continued to exist with its financial duties. The responsible authority changed; the everyday name did not.
Anyone looking for the VMSW bestek today is looking for the BBW. That is not a detail. Both names lead to the same text, but several editions are in circulation, and the edition is what counts.
What BBW 2025 changes
BBW 2025 appeared in the Belgian Official Journal on 25 February 2026 and takes effect ten days after that publication. It follows BBW 2015, ten years later.
The main structural change is the numbering. Item numbering goes from six digits to seven, so that standardised items can be introduced. Articles that could carry several measurement codes were split into separate article numbers. That second change matters more than it sounds: it is not only the codes that move, it is the way the text is divided.
On substance, the new edition follows what has arrived on site. BBW 2025 adds items for CLT timber construction, steel frame construction, ETICS with hard cladding, external solar shading, outdoor ceilings, and vacuum insulation and glazing. Circular construction, fire safety and acoustic comfort were revised.
The transition: 2026, 2027, 2028
2026 is a year of choice. The client and the designer may work with BBW 2015 or with BBW 2025.
From 1 January 2027, every social housing project whose preliminary design Wonen in Vlaanderen approves must use at least BBW 2025. Existing projects move across by 2028 at the latest.
Two habits follow for anyone opening a file now. Check which edition the contract designates before you open the first article, because in 2026 there can still be two. And for a file that will cross 1 January 2027, take the new text from the start instead of migrating halfway.
How the text is put together
The BBW has ten parts, the delen, numbered 0 to 9.
| Deel | Title |
|---|---|
| 0 | Aanneming/werf — contract and site |
| 1 | Onderbouw — substructure |
| 2 | Bovenbouw — superstructure |
| 3 | Dakwerken — roofing |
| 4 | Gevelsluiting — façade closure |
| 5 | Binnenafwerking — interior finishing |
| 6 | Technieken fluïda — fluid services |
| 7 | Technieken elektriciteit — electrical services |
| 8 | Schilderwerken — painting |
| 9 | Omgevingswerken — surroundings |
Below the deel come the hoofdstuk, the sectie and the artikel. The code gives away the place in the tree: a hoofdstuk belongs to the deel whose digit its code starts with, so deel 8 holds hoofdstukken 80 to 89. Reading the numbering is therefore enough to place an article, without the table of contents.
The bill of quantities goes with the text without being part of it. Wonen in Vlaanderen publishes the summary measurement — the samenvattende opmeting, or SO — with the administrative specification VM/B2017, valid from 1 January 2025. The technical text says what is built and how it is measured; the summary measurement is the document the contractor prices.
Where it applies, and where it does not
The BBW is written for social housing, and that is where it binds: the obligation covers every social housing project whose preliminary design Wonen in Vlaanderen approves.
Elsewhere it is a common reference rather than an obligation. Private clients and other authorities may point to it, and many Flemish practices do, because the text covers the trade and it is in Dutch. The obligation then does not come from the BBW: it comes from the special specification, from subsidy conditions or from the contract.
The rule is the one that holds for every standard specification. The special specification designates the reference text and its edition. When it does not say, ask the client before you write, not after the tenders.
It is not a translation of the CCTB
Wallonia has the CCTB, Flanders has the BBW. They are two separate documents from two different authorities.
They are not aligned. The numbering differs, the division into articles differs, the measurement clauses do not always count the same way, and the BBW exists only in Dutch just as the CCTB exists only in French. An article in one has no direct counterpart in the other.
The practical consequence: a practice working in both regions keeps two libraries. Translating numbers does not work, and a firm library built on one text cannot be carried over to the other.
In ArchiMind
BBW 2025 is available in ArchiMind as an official template, in Dutch. You start a project from it and work in the structure of the text itself: the levels are called Deel, Hoofdstuk, Sectie and Artikel, and the numbering stays the one in the bestek.
One thing is not possible today: creating your own template on the VMSW referential. That option does not exist yet. If you import your own specification as a Word document, you get a template of your own with no referential attached — usable, but not the official BBW template.
Choosing a referential does not replace checking. Confirm the edition your contract designates, and read the project-specific clauses.
What to remember
The VMSW bestek and the Bouwtechnisch Bestek Woningbouw are the same text. The edition that counts is BBW 2025, in the Belgian Official Journal of 25 February 2026, mandatory for new social housing files from 1 January 2027. Item numbering went from six digits to seven, so a library built on BBW 2015 cannot be carried across unchecked. And the BBW is not a Dutch version of the CCTB.
Read next: which standard specification applies to your project, the CCTB in detail, QUALIROUTES, and the definitions of the VMSW reference, specification and bill of quantities.
Sources and references
Frequently asked questions
Are the VMSW bestek and the Bouwtechnisch Bestek Woningbouw the same text?
Yes, they are two names for one document. Bouwtechnisch Bestek Woningbouw is the official name and Wonen in Vlaanderen is the publisher. The name VMSW bestek survives from the years when the Vlaamse Maatschappij voor Sociaal Wonen issued the text. Searching for the VMSW bestek means searching for the BBW.
Which edition of the BBW should you use?
The one your contract designates. During 2026 the client and the designer may choose between BBW 2015 and BBW 2025. From 1 January 2027, every social housing project whose preliminary design Wonen in Vlaanderen approves must use at least BBW 2025, so the choice closes.
Does the numbering change in BBW 2025?
Yes. Item numbering goes from six digits to seven, so that standardised items can be introduced, and articles that could carry several measurement codes were split into separate article numbers. A firm library built on BBW 2015 therefore cannot be carried across without checking it article by article.
Does the BBW apply outside social housing?
Not as an obligation. The text is written for social housing and that is where it binds. Elsewhere it is a common Dutch-language reference that a client may point to. The obligation then comes from the special specification, from subsidy conditions or from the contract, never from the BBW itself.
Is the BBW a Dutch version of the CCTB?
No. They are two separate documents from two different authorities, each with its own content, numbering and update rhythm. An article in the CCTB has no direct counterpart in the BBW. A practice working in both regions keeps two libraries rather than translating numbers between them.
Where is the bill of quantities that goes with the BBW?
In the administrative specification, not in the technical text. Wonen in Vlaanderen publishes the summary measurement, the samenvattende opmeting, with specification VM/B2017, valid from 1 January 2025. The technical text says what is built and how it is measured; the measurement is the document the contractor prices.