Bottom line: Adding floors means building on the structure — a common area. The decision never belongs to a single co-owner: it is taken in general assembly, by a high majority. It usually combines several decisions (heavy works, alienation of a common area, recalculation of the shares), each with its own threshold, and requires planning permits to be feasible at all.
1. Who holds the "right to add floors"?
This is the starting point, and it often surprises the top-floor co-owner who believes they are "at home" above. Unless the condominium bylaws provide otherwise, the ground, the structure and the foundations are common areas belonging to all the co-owners. Building above the building means using and transforming these common areas: the right to add floors is therefore not a private right held by the owner of the top level or the terrace.
This right falls to the collective body of co-owners, which decides in general assembly. The only exception is an express allocation in the condominium bylaws or the deed of division — for example where a developer reserved, at the outset, the right to add floors. To understand the boundary between private and common, see our complete guide to Law 18-00.
2. Why adding floors is one of the heaviest decisions of the condominium
Adding floors combines several features that place it at the very top of the scale of required majorities:
- It affects the structure — you must check that the structure and foundations can bear the additional levels, which may require reinforcements.
- It modifies the external appearance of the building — adding a floor changes the silhouette of the building.
- It may entail the alienation of a common area (the volume above the building, the right to build) in favour of whoever carries out the operation.
- It creates new lots and therefore requires redistributing the shares among all the co-owners.
In our articles on works on common areas and on the 106-12 reform, adding floors, the sale of a common area and the change of shares are among the matters subject to the most demanding qualified majorities — or even unanimity where there is alienation of an essential common area or a change in the purpose of the building.
3. What majority must be reached in general assembly?
There is no single answer: the majority depends on the exact nature of the operation and on what your condominium bylaws provide. In practice, adding floors generally combines several decisions, each with its threshold:
- Authorise works affecting the structure and the external appearance — falls under the highest qualified majority, with unanimity or a very large majority often required by the condominium bylaws.
- Transfer the right to add floors (alienate a common area) — an alienation decision, which may require unanimity where the common area at stake is essential.
- Change the distribution of the shares after the lots are created — qualified majority (in practice, often three quarters of the votes).
In other words: as long as a single one of these locks is not cleared by the required majority, the operation cannot validly proceed. This is why the exact majority is determined case by case, with your notary, in light of the condominium bylaws and the applicable regulations. A decision taken by an insufficient majority is exposed to annulment — see our article on contesting general assembly decisions.
The smart move: value the right to add floors before voting its transfer
The right to add floors has a value — it is, in essence, the right to create additional buildable square metres above the building. When the condominium is about to transfer it to a co-owner or a third party, the decisive question is: at what price? Selling too low deprives all the co-owners of a collective asset. An independent appraisal report compliant with RICS (Red Book) standards — realistic buildable area in light of planning rules, market value of the lots to be created, technical costs and constraints, discount for construction risks — gives the assembly an objective basis to negotiate and to split the proceeds of the transfer among the co-owners. It is also the document that defuses disputes: everyone sees how the price was set. Report in 5 to 8 days (48–72 h express), from 3,500 MAD excl. tax, firm quote within 24 h.
4. Transferring the right: to a co-owner, or a third party?
Once the principle is acquired, two structures recur most often:
- Transfer to an existing co-owner — typically the top-floor owner, who extends their lot upward or creates a duplex. The condominium transfers the right to add floors; the co-owner finances and carries out the works.
- Transfer to a third party (developer, investor) — the condominium sells the right; the third party builds the new levels, becomes their owner, and enters the condominium as a new co-owner of the created lots. The proceeds of the sale go to the condominium and benefit, depending on what is decided, all the co-owners.
In both cases, the transfer bears on a common area (the right to build above the building): it requires a general assembly decision by the required majority, a notarised deed and publication at the land registry to be enforceable against third parties. The price is negotiated freely — hence, again, the value of an independent appraisal upstream.
5. The recalculation of the shares: the step that affects everyone
This is the effect of adding floors that co-owners underestimate the most. By creating new lots, you increase the total value of the building and change the relative share of each existing lot. Yet the shares — the proportion of common areas attached to each lot — determine both the voting weight in assembly and the distribution of charges.
A new distribution is therefore required: existing lots mechanically see their share diluted by the arrival of the lots created in the addition. This operation requires:
- Reassessing the relative value of each lot, old and new, according to the criteria of Law 18-00: area, location within the building, consistency.
- Voting the change of shares by the required qualified majority (in practice, often three quarters of the votes).
- Updating the descriptive statement of division and the condominium bylaws by notarised deed, then publishing at the land registry.
A poorly-documented recalculation is a classic source of litigation: this is precisely where a transparent appraisal protects the decision. Our condominium advisory supports the assembly through this step.
6. Planning permits: feasibility before the vote
Adding floors is major work subject to a building permit and to compliance with the applicable planning rules — authorised height, envelope, alignment, parking, setback. Even before convening the assembly, you must ensure the operation is legally and technically permissible:
- Does the municipality's planning document authorise one more level at this location? The residual buildable height conditions the whole project.
- Can the existing structure bear the load of the added levels, or are reinforcements needed (and at what cost)?
- Are the ancillary constraints — additional parking spaces, access, connections — satisfiable?
Voting an addition without having checked feasibility means risking an unworkable decision. A technical and regulatory feasibility study must therefore precede the general assembly: it states what is buildable, on what conditions, and at what cost — data essential to value the transferred right correctly.
7. Our take: the order of operations that secures the project
- Step 1 — Feasibility. Check planning (buildable height, permit) and the capacity of the structure. Without this, nothing else makes sense.
- Step 2 — Check the condominium bylaws. Is the right to add floors allocated to someone, or does it remain common? What majorities do the bylaws require for the structure and the alienation of common areas?
- Step 3 — Value the right. Have the value of the right to add floors and the value of the lots to be created quantified by an independent expert, before setting a transfer price.
- Step 4 — Decide in assembly. Submit to a vote, by the required majority, the principle of the addition, the transfer of the right, and the recalculation of the shares.
- Step 5 — Formalise. Notarised deed, update of the descriptive statement of division and the bylaws, publication at the land registry, then filing of the building permit.
Related articles
To document the value of the right to add floors or of the lots to be created, use our independent RICS appraisal service and browse more analyses on the ReaConsult blog.