Owners in older Bulgarian apartment blocks are increasingly receiving the same offer: a developer wants to add one or two floors on top of the building and, in return, offers a new roof, a refurbished façade, a lift or cash. It sounds like a deal with no losers. In practice it is one of the most complex transactions in a condominium — and one of the riskiest if it is rushed.
This guide explains what Bulgarian law requires before a floor can be added to (or an extension built onto) a building in condominium ownership, what the owners actually give up, and what to check if you are buying a flat in such a block or in the new floors themselves.
The legal framework was checked against the consolidated texts of the Spatial Planning Act (ЗУТ), the Property Act (ЗС) and the Condominium Management Act (ЗУЕС) as of October 2026. Construction legislation changes — check the current wording before any specific transaction.
The starting point: the roof, the land under the building, the foundations, external walls, staircases and floor slabs are common parts owned by all the owners (Art. 38(1) of the Property Act). The owner of the top-floor flat has no more rights over the roof than the owner on the ground floor.
That is why no single owner — and not the building manager either — can "sell the roof". The right to build on top of the building is granted by everyone.
Adding floors to, or extending, a building in condominium ownership is permitted on the basis of two documents (Art. 183(2) ЗУТ):
A right to add floors can only be granted over an existing building (Art. 66(4) ЗС). Where the state or a municipality owns the land or a unit in the building, the contract and the consent are given in writing under the special rules for public property (Art. 183(3) ЗУТ).
A general meeting does not replace the signatures. Under the Condominium Management Act, the general meeting can decide to take steps towards adding floors or extending, but only with 100% of the undivided shares in the common parts (Art. 17(2)(1) ЗУЕС). The building manager can represent the owners in such a deal only if expressly authorised by the general meeting (Art. 23(3) ЗУЕС). And even with a unanimous decision, the Spatial Planning Act still requires notarised consent from each individual owner.
In practice, one owner who says no — or one heir nobody can trace — stops the project.
The contract is signed with the owner of the plot. In most blocks that means the flat owners themselves, holding the land in undivided shares — but not always. In some buildings put up under state programmes, the land may belong to the municipality or the state.
Before any negotiation, pull out the title deeds and check in the property register whether they include a share of the land. If they do not, the first job is to establish who owns it — that is who the contract will be with.
Where adding floors affects the structure of the building, a building permit can be issued only after a structural survey under Art. 176c ЗУТ (Art. 148(13) ЗУТ). The survey is carried out by a licensed consultant or by designers with full design qualifications, and the team must include an engineer qualified to perform technical control of the structural design.
For owners this is the single most important document in the whole process. Ask for it, read the conclusions, and do not sign a consent until you know what it says about the building's load-bearing capacity and what strengthening it calls for.
This is the part almost nobody explains to owners.
When floors are added, the new owners acquire, against payment, a share in all the common parts of the building, including the land. Everyone's shares are recalculated according to the value of each unit at the time the construction is completed (Art. 40(2) ЗС).
In other words, every existing owner will hold a smaller percentage of the land and the common parts. That has two practical consequences:
Every contract is different, but in our experience these points decide whether the owners are protected:
Before signing, the contract should be reviewed by a lawyer acting for the owners, not by the developer's lawyer.
Not every change upstairs is an added floor. If you want to convert your own attic storage room without touching the common parts, the rules on alterations apply (see our guide to renovating a flat in an apartment block).
It is different if the project annexes a common part — a shared attic, corridor or drying room — to your unit, or creates a new separate unit from it. That requires a contract transferring ownership, as a notarial deed, with the other owners (Art. 185(3) ЗУТ), and where common parts are taken over, the consent of all owners with notarised signatures (Art. 185(2) ЗУТ). If the attic is turning into a home or a studio, also check the rules on change of use.
When we view a flat — especially on the top floor — we check the property register for a registered contract granting a right to add floors over the building. If there is one, the buyer needs to know that construction may start above them: noise, scaffolding, a temporary roof and a risk of leaks over the following years.
We also ask the building manager whether there have been talks with a developer, whether the general meeting has taken a decision and whether the building has been surveyed.
Here the checks go further than usual:
New floors on an older building can be an excellent purchase — a new home in an established location. But only if every link in that chain is in place.
Adding floors to an apartment block requires a notarial contract with the owner of the land and notarised consent from every owner, and — where the structure is affected — a structural survey before the building permit. In return for the compensation, owners give up part of their share in the land and common parts. A good contract deals with deadlines, security and liability for damage, not just "the new roof".
If your building has received an offer to add floors, or you are thinking of buying in such a building — call us or come into the office. We will go through the documents and tell you what is missing before you sign.
