Building permit when dividing an apartment building into units: when it is required

Two levels: legal division and the physical reality of the building

Converting an apartment building (činžovní dům) into units for sale involves two separate levels. The first is legal: the owner declares the building divided into units, and the declaration is registered in the Czech Land Registry (katastr nemovitostí). The second is construction-related: the real building must match what the declaration describes, and any alterations must go through the correct building-law procedure.

The two levels are governed by different legislation. The creation of units is regulated by the Civil Code No. 89/2012 Coll. (Section 1158 et seq.), while building works and the use of buildings fall under the Building Act No. 283/2021 Coll. Owners often deal only with the first level and run into the second when preparing the sale. It therefore pays to assess both together and early.

When an owner's declaration is enough

Under Section 1159 of the Civil Code No. 89/2012 Coll., a unit is a flat or non-residential space defined by the declaration. A flat is a set of rooms which, by their technical layout, are intended for living. The owner's declaration (Section 1166 et seq.) is a unilateral legal act and is registered in the Land Registry under the Land Registry Act No. 256/2013 Coll.

If the building already consists of separate, functioning flats and non-residential spaces, nothing is being built and the use is not changing, a building permit is usually not needed for the declaration itself. This assumes that the actual state matches the documentation and that the flats are really used for their intended purpose.

Note: the fact that no permit is needed does not mean building law is irrelevant to the building. A mismatch between reality and documentation will surface when the units are being defined and may delay the preparation of the declaration.

When the building authority becomes involved

The building-law regime is triggered as soon as something changes physically or functionally before or during the conversion. Typical situations:

• change of layout – merging or splitting flats, new partition walls, closing up or knocking through openings;
• interventions in load-bearing structures or the building's structural stability;
• changes to utilities – new risers, separate metering, ventilation, chimneys and flue routes;
• change of use – for example converting a non-residential space (storage, workshop, office) into a flat, or an attic into a residential unit;
• extensions, internal fit-outs and additions that create new units;
• fire-safety and hygiene changes resulting from the new layout.

The type of procedure required is set by the Building Act No. 283/2021 Coll. and assessed by the building authority. Minor alterations may be handled more simply; larger ones require a building permit. Without knowing the specific building and the planned works, nothing generally binding can be said.

Permit, notification, change of use and final inspection

The Building Act No. 283/2021 Coll. has applied since 2024 and changed the terminology you may be used to. The former “notification of building alterations” (ohlášení stavebních úprav) has been replaced by the notification of a building project (oznámení stavebního záměru); alongside it there is the building permit and works that need neither. Check the exact classification of your project with the building authority or a designer, because the rules in this area change and the interpretation depends on the individual case.

Building permit

This generally applies to larger interventions – structural work, extensions, fit-outs or major layout changes. It is filed together with project documentation.

Notification of a building project

This is used for certain smaller projects and alterations. Even here, the building authority assesses the project and the statutory conditions must be met.

Change of use and final inspection

When the purpose for which a building or part of it is used changes (for example, a non-residential space becomes a flat), this is a separate matter requiring the building authority's consent or decision. Completed alterations that require it are checked through the final inspection procedure (kolaudace) before use. Without proper use in line with the permit, you face problems both when selling and when buyers seek financing.

How permits affect the timetable

Specific time limits cannot be given here: they depend on the scope of the project, the completeness of the documents, the opinions of the authorities concerned and whether the proceedings need to be supplemented. For planning purposes, the order of steps matters:

1. First, establish whether any construction part is needed at all and under which regime.
2. Only then draw up the sales schedule, because selling units that cannot be properly used is risky.
3. Time the owner's declaration and the registration in the Land Registry so that they match the actual state of the building.

If no building works are needed, the timetable shrinks to preparing documentation, the declaration and registration. Ownership of a unit passes only on registration in the Land Registry (vklad), and under the Land Registry Act No. 256/2013 Coll. the registry office may not decide earlier than twenty days after notifying the owner. These steps follow only once the construction part is resolved.

There is also an economic side. The difference between selling a building as a whole and selling it by units is typically +20–40%, but the exact figure is determined only by a feasibility study. The cost and time of permits must be built into this calculation, otherwise the result is distorted. For a rough estimate you can use the building potential calculator, but it does not replace an assessment of the specific building.

The permit gate: how permits are controlled within a project

A building transformation project passes through three gates: legal, permit and sales. You move to the next phase only with confirmed figures. The permit gate is designed for building-law questions – it verifies whether a permit, notification or change of use is needed, and whether the project is documented well enough to be planned reliably.

In practice this means sales are not launched on the assumption that “it will somehow pass”. Until it is confirmed under which regime the works will be handled and how they affect budget and time, the project does not move into the sales phase. The whole scheme of eight phases and three gates is described on the page How it works. The building-law assessment is part of the paid feasibility study Audit and plan, delivered within six weeks. If you want the whole process, including the permitting part, managed under a single contract, see End-to-end delivery.

Checklist of documents before filing

Before approaching the building authority or a designer, gather the following:

• an extract from the Land Registry and a cadastral map extract;
• available original and later documentation of the building (floor plans, sections, utility layouts);
• earlier building authority decisions – building permit, final inspection decision or consents, and records of changes of use;
• a current survey of the actual state and a comparison with the existing documentation;
• a list of all flats and non-residential spaces, including their actual use and tenancies;
• a list of the intended works (layout, utilities, attic, cellars, common areas);
• structural, fire-safety and, where relevant, heritage-protection information;
• a clear division of what is a unit and what are the common parts of the building.

If any document is missing, treat it not as an obstacle but as a first task. Completing the documentation is a normal part of preparation. You will find more context in the blog on transforming apartment buildings.