Is a change of a building before completion possible under the new Building Act?
Yes, but not as a separate permit. Until 31 March 2025 the building office could permit a change of a building before its completion. It did so in justified cases, on the builder's application (§ 68 of Act 50/1976 Zb.). Act 25/2025 Z. z., the Building Act, which applies from 1 April 2025, has no such permit for new cases.
The short answer to the question of which section to look up: § 43 (control inspection of the building) and § 65 ods. 7 (verification of a change of the project). The term change before completion appears in Act 25/2025 only in the transitional provisions (§ 84).
The article follows the version of the act in force from 1 November 2025 to 31 December 2026. The whole construction process is in the main article on building a house.
What counts as a change and what is a minor deviation?
The act has no category of "insignificant deviation" that could be agreed on site without the office. It works with one concept: a deviation from the verified project of the building. Work carried out against the verified project is unauthorised building work (§ 28 ods. 1).
The line between a small and a large change is drawn by the test in § 43 ods. 2. A deviation can be handled on site if it does not conflict with:
- the decision on the building intent,
- the conditions of the affected authorities in their binding opinions,
- the conditions of the affected legal persons in their binding statements.
The decision on the building intent approves the building intent. That is the urban, architectural and basic structural design of the building, including its siting and its connection to utility networks (§ 9 ods. 2, § 60 ods. 1). If a change touches these matters, it may conflict with the decision and cannot be handled under § 43 ods. 2. If a deviation cannot be permitted that way, the building office sets the next step (§ 43 ods. 3).
| Kind of change | Procedure | Role of the building office | Provision |
|---|---|---|---|
| Deviation that conflicts neither with the decision nor with the conditions of the affected authorities and legal persons | Extraordinary control inspection. The designer marks the change in the project and the site manager records it in the minutes and the diary | The office attends the inspection or approves the minutes within three days | § 43 ods. 2, 3 |
| Deviation that cannot be permitted that way | Verification of the change of the project with compliance clauses, 30-day period | Verifies the change if the compliance clauses are favourable | § 43 ods. 3, § 65 ods. 2, 7 |
| Deviation for which the office orders a new procedure | New building intent proceedings | Determines that a new procedure is needed | § 43 ods. 3 |
Who applies for a change, and with which documents?
The change is proposed by the site manager, the designer or the person appointed as construction supervisor. The builder calls the extraordinary control inspection, and does so before the work is carried out (§ 43 ods. 2).
- The designer prepares the design of the change.
- The builder calls the extraordinary control inspection. The building office may attend (§ 43 ods. 3).
- If the test is passed, the designer marks the change in the project. The site manager records it in the minutes and the diary (§ 43 ods. 2). The site manager, the designer, the construction supervisor and the office employee sign the minutes. The builder or the site manager records them in the information system (§ 43 ods. 4).
- If the office did not attend, it approves the minutes sent to it within three days of delivery (§ 43 ods. 3).
If the office orders verification, the builder files an application on the form in annex 6 of Decree 60/2025 Z. z. (§ 4 ods. 6). The form asks only for the data that changed against the project. The documents are either stored in the information system or attached on paper (annex 6, part E). They are:
- the project documentation of the change of the project,
- the minutes of the extraordinary control inspection,
- all compliance clauses of the affected authorities and affected legal persons,
- the details of the administrative fee.
The office has 30 days to verify and compares the change with the decision and the conditions of the affected authorities (§ 65 ods. 2, 3, 7). If the compliance clauses are not favourable or the change does not match the decision, the office returns the application with its reasons. Against the return, a complaint can be filed with the appeal body within ten working days (§ 65 ods. 4).
The administrative fee for a change of the project during construction is 50 % of the project verification rate (Act 145/1995 Z. z., položka 59 písm. b bod 7). For a building with one or two dwellings the fee is 45 euro if the project was verified with the building intent. It is 75 euro if it was verified separately.
What do the designer, the construction supervisor and author's supervision do?
The roles are explained in the article on construction supervision and author's supervision. For a change:
- The designer must attend a control inspection to which they are invited. Reasons are a change of the project, or a swap of building products or building technical systems (§ 35 ods. 7 písm. a). The designer is not liable for changes they did not approve (§ 35 ods. 10). The designer may approve a change of the project only after the fire protection specialist has pre-approved the part it touches (§ 35 ods. 11).
- The construction supervisor asks for deviations to be removed and records unremoved ones in the diary (§ 36 ods. 1 písm. f). On a reserved structure the supervisor also reviews the contractor's changes. The designer or the fire protection specialist approves them first (§ 36 ods. 2 písm. a).
- The site manager records the deviation in the minutes and the diary (§ 43 ods. 2). At the end the site manager writes the final opinion. It states that the building conforms to the verified project, including the approved changes (§ 37 ods. 2).
- Author's supervision is the right of the author of the architectural work to review whether the work follows their design (§ 35 ods. 10).
What happens if you build the change without approval?
Work against the verified project is unauthorised building work (§ 28 ods. 1). The consequences come in steps:
- If a control inspection finds it, the building office calls for it to stop and informs the building inspectorate (§ 43 ods. 6).
- The building inspector calls for the building to be brought into line with the verified project within a set period (§ 73 ods. 1).
- The building inspectorate orders the owner to remove a building, a change or an alteration made by unauthorised building work (§ 74 ods. 8 písm. d).
- Building against the verified project is a misdemeanour with a fine from 30 to 15 000 euro (§ 79 ods. 3 písm. a, ods. 6 písm. c). A sole trader or a legal person pays 10 000 to 150 000 euro (§ 80 ods. 4 písm. a).
- The office stops kolaudácia if the building stands against the verified project (§ 66 ods. 8).
The current text of the act has no general procedure to permit such a change afterwards. The transitional rule in § 84 ods. 7 písm. b) keeps a later permit under the old rules for buildings that meet the old conditions. The application must be filed by 31 March 2029. The building office can tell you whether a particular building qualifies. The amendment brings new options from 2027.
How do changes show up at kolaudácia?
At occupancy approval (kolaudácia) the office examines whether the building is fit for use in line with the verified project (§ 66 ods. 4 písm. a). Changes are documented in the attachments to the kolaudácia proposal. By type of building these include (§ 66 ods. 2 písm. a to c):
- The construction diary, in which the contractor records the agreed changes against the verified project (§ 32 ods. 3) and where every control inspection is recorded (§ 43 ods. 5).
- The site manager's final opinion, which certifies that the finished building conforms to the verified project, including the approved changes (§ 10 ods. 3, § 37 ods. 2).
- As-built documentation, which the contractor or the designer arranges (§ 32 ods. 3, annex 21). Its summary report describes the deviations, their reasons and an assessment of their conformity with the decision and the verified project. The drawings mark the changes against the verified project (Decree 60/2025 Z. z., annex 21).
It may be a copy of the verified project with the deviations drawn in. This works if the deviations do not require a new verification of the project (annex 21).
How does the old 1976 procedure differ?
Under § 68 of Act 50/1976 Zb. the office dealt with the change as a separate matter and issued a decision. The provisions on building proceedings applied by analogy.
| Aspect | Until 31 March 2025 (Act 50/1976 Zb.) | From 1 April 2025 (Act 25/2025 Z. z.) |
|---|---|---|
| Procedure | Permit for a change of a building before completion (§ 68) | Extraordinary control inspection, verification of the change of the project, or new building intent proceedings (§ 43 ods. 2, 3) |
| Outcome | A decision permitting the change or rejecting the application | Approved minutes, or a verification clause for the change of the project |
| What the office assesses | Rights of the parties to the building proceedings and interests of the affected authorities | Conformity with the decision on the building intent and the conditions of the binding opinions and statements |
| Link to kolaudácia | The change procedure could be joined with the kolaudácia proceedings if the building did not depart substantially from the verified documentation (§ 81 ods. 4) | A building against the verified project means kolaudácia is stopped (§ 66 ods. 8) |
The old rules are not only history. If a building has a zoning decision or a building permit under the old rules, the old rules apply (§ 84 ods. 5, 6). That includes an application for a change before completion filed after 31 March 2025. The building office competent under the old rules runs it (§ 84 ods. 8). For a house under construction with an old permit, first establish which regime applies.
What changes from 1 January 2027?
Amendment 243/2026 Z. z. changes, among other things, § 18, § 43 and § 62 from 1 January 2027. It is not current law yet.
- Handling a deviation on site gets a new condition. The owner of the land or the building may be someone other than the builder. Their rights must not go beyond the decision. If they do, the builder must submit the owner's verified consent (Čl. I bod 105).
- The office will have seven working days instead of three days to approve the minutes (Čl. I bod 106).
- Deviations that cannot be permitted under § 43 ods. 2 are added to the grounds for changing the decision on the building intent (Čl. I bod 133).
- A decision on the building intent will be able to permit afterwards work done from 1 April 2025 to 31 December 2026 without a verified project or against it. Covered results are a change of a completed building, a building alteration, a terrain alteration, an outdoor alteration and a structure with an ancillary function to the main building (Čl. I bod 58). The amendment sets further conditions.