How Shares in the Common Parts of an Apartment Building Are Determined When It Is Divided into Units

When shares arise and what they are based on

A building is divided into units under the Civil Code, Act No. 89/2012 Coll. (Section 1158 et seq.), most often by an owner's declaration (prohlášení vlastníka). In it the owner describes the building, defines the units and sets the size of the share in the common parts that belongs to each unit. The unit and the share form a single whole: the share cannot be transferred without the unit, or vice versa (Section 1160 of the Civil Code).

Common parts typically include the foundations, roof, external walls, staircases, utility risers and other parts that serve more than one unit. What counts as a unit and what as a common part must be settled before the shares themselves, otherwise both the numerator and the denominator of the calculation rest on incorrect data.

The default rule: ratio of floor areas

The Civil Code starts from the ratio of the unit's floor area to the total floor area of all units in the building. This is the clearest yardstick, and a buyer can easily verify it. The law also allows the declaration to set the share in another objective way, provided the method is clearly described in the declaration. Check the exact wording of Section 1160 and related provisions in the current legislation.

A practical note: ancillary spaces, such as cellar compartments, loft areas or balconies, must be consistently either included in or excluded from the calculation. One uniform rule for the whole building matters more than which rule you choose; inconsistency later turns into disputes between owners.

Impact on voting in the owners' association

In practice, the share in the common parts translates into voting weight at the members' meeting (Section 1206 of the Civil Code), unless the bylaws provide otherwise. This has consequences for future relations in the building:

• Where a few large units dominate, their owner can push decisions through alone, which buyers regard as a risk.
• If an owner divides the building and keeps the larger share of the units, they retain control over management but make the smaller units harder to sell, because new owners will have limited influence.
• Where shares are evenly balanced, decisions are reached by agreement, which increases buyer confidence but may slow the approval of repairs.

The allocation of votes is therefore not a mere formality: it is part of the offer that buyers assess, just as they do the layout or condition of the flat.

Impact on costs and saleability of units

Unit owners generally contribute to the management of the building in proportion to their shares (Section 1180 of the Civil Code), unless they agree otherwise. The share therefore influences the amount of contributions to the repair fund (fond oprav) and the apportionment of shared costs, such as insurance, cleaning or roof repairs.

The economic logic is simple. A share that is too low for a profitable unit means its owner bears fewer costs than the benefit received, and the other owners see this as unfair. A share that is too high for a small unit puts buyers off with higher contributions. A disproportionate allocation shows up in both the price and the time to sell. Selling by individual units can typically bring a 20–40% higher value than selling the building as a whole; the exact figure depends on a feasibility study, and fairly set shares are one of the conditions for that potential not to be lost in disputes. You can make a rough estimate with the potential calculator.

Checklist of documents

Before the shares are calculated and registered, verify the following documents:

1. A current survey of the building and floor plans of all storeys that reflect the actual state.
2. Floor areas of individual rooms and a uniform methodology for counting areas.
3. A list of ancillary spaces (cellars, loft storerooms, storerooms, balconies, gardens) with their allocation to units.
4. Definition of the common parts and of any parts that will serve only certain units.
5. Consistency of the approved use of the spaces (flat, non-residential premises) with the documentation; assess any changes under the Building Act, Act No. 283/2021 Coll.
6. An extract from the Land Registry and details of any encumbrances (mortgages, easements (věcná břemena), enforcement proceedings).
7. Draft bylaws or cost-apportionment rules, so that they match the shares.

Mistakes that complicate Land Registry registration

Ownership of units arises upon registration in the Land Registry (katastr nemovitostí); the cadastral office may not decide earlier than twenty days after notifying the owner (Act No. 256/2013 Coll.), and the average time for registration is roughly twenty-two days. Every error extends this period. The most common are:

• the sum of the shares does not add up to the whole or differs from the survey data,
• a difference between the floor areas in the declaration and in the survey documents,
• unclear or missing ancillary spaces of the units,
• unresolved encumbrances on the property, such as a mortgage (zástavní právo),
• insufficiently defined common parts.

Correcting a mistake after registration is harder than checking beforehand, because it often requires the consent of several owners. Consider having the documents reviewed by an independent person before filing. If a sale takes place, payment is normally made by bank transfer, for example via a lawyer's escrow account; cash payments are limited by Act No. 254/2004 Coll. to CZK 270,000 per day. Details of how we work together can be found under Audit and Plan.