Distribution of shares and thousandths in co-ownership

When purchasing an apartment, you become the owner of a private unit and simultaneously a co-owner of the common areas of the building. This ratio is established through a distribution of shares, usually expressed in thousandths.

This distribution determines not only your voting rights within the co-ownership, but also your share in costs, charges, and decisions.

Base deed and co-ownership regulations

The rights and obligations of each co-owner are established in:

• the base deed
• the co-ownership regulations

Together, these form the statutes of the building.

The base deed includes, among other things:

• the description of the building
• the distribution of shares in the common areas
• the associated plans and technical documents

How are shares and thousandths determined?

The distribution of shares is not arbitrary. It is calculated based on the relative value of each private unit.

This takes into account:

• the net floor area
• the destination (residential, commercial, storage, …)
• the location (floor, orientation, accessibility, …)

This calculation is performed by means of a reasoned report.

Reasoned report (Art. 577-4 Civil Code)

According to Article 577-4, §1 of the Civil Code, the distribution of shares in the common areas must be based on an objective valuation.

A land surveyor-expert prepares a reasoned report for this purpose, in which:

• the valuation criteria are explained
• the calculation method is justified
• the final distribution of shares is established

This report forms the basis for inclusion in the base deed.

Who is authorized to calculate thousandths?

The calculation of shares and thousandths in co-ownership is a task performed by:

• land surveyor-experts
• or architects

In practice, this is often entrusted to a land surveyor-expert, due to the combination of geometric and legal expertise.

Relationship with pre-cadastration

When splitting a plot or building, pre-cadastration is often also required.
This involves a delimitation plan, drawn up by a land surveyor, being submitted in advance to the General Administration of Patrimonial Documentation (GAPD).

The GAPD assigns a reference number, which is included in the notarial deed.
This occurs before the final assignment of new cadastral parcels.

Why is a correct distribution so important?

An incorrect or unclear distribution of shares can lead to:

• disputes within the co-ownership
• incorrect cost allocation
• legal disputes during sale or revision

A correct calculation ensures transparency and legal certainty for all parties.

Want to know more?

Would you like to know how thousandths are calculated in your building, or do you need an (anonymized) example of a reasoned report?
Please feel free to contact us for further explanation or advice.