Buying a Czech apartment with undocumented alterations

The listing says “fully remodelled”, but the current layout may not match the approved documentation or the owner declaration. Before reserving the apartment, identify what changed, which approvals were required, whether common parts were affected and who will bear the risk of correcting the records or the work.

Red flags during the viewing

• The floor plan in the listing differs from the title documents, owner declaration or archived plans.
• A kitchen, bathroom or room was moved, a new opening was cut, or a wall was removed.
• Windows, balcony, risers, ventilation, heating or other common parts were changed.
• Residential-looking space is registered or permitted for a different use.
• The seller has invoices and photos but no approved documentation or authority record.
• The seller says the buyer can “legalise it later” without a written technical and legal path.

Build an evidence chain

Start with the unit's title sheet and owner declaration, then request the building's approved documentation and the records for the alteration. Compare them with a measured survey of the actual state. Minutes or consent from the owners' association can answer private-law questions about common parts, but they do not replace a public-law permit where one was required. Equally, an authority record does not settle every ownership or association issue.

Missing plans and an unlawful alteration are not the same problem

If original documentation was lost or is incomplete, the owner may need a simplified record of the existing building. The government's building passport guidance explains that a passport is used where documentation was not preserved or is not in proper condition and the building was permitted, or did not require permission when constructed. A passport is therefore not automatic proof that an alteration which required approval has been retrospectively authorised.

Check actual permitted use

A space marketed as an apartment, studio or atelier may have a different permitted use. Ask for the relevant approval and verify the record with the competent building authority. Current government guidance on a change of use shows that the process depends on the proposed use and whether construction work requiring a permit is involved.

Who should inspect what?

• Building surveyor or architect: measure the actual state and identify structural, fire, acoustic, ventilation and services implications.
• Owners' association or manager: provide the owner declaration, building documentation, consents and records affecting common parts.
• Building authority: confirm available files, permitted use and the appropriate procedure; obtain written records rather than relying on a phone summary.
• Independent property lawyer: reconcile public-law, ownership and contract risks and draft the completion conditions.
• Bank and insurer: confirm whether the discrepancy changes valuation, security acceptance or cover.

Protect the reservation and purchase contract

• List the discrepancy precisely; avoid a vague statement that the buyer knows the condition.
• Require specified documents and approvals before the reservation fee becomes non-refundable.
• State who must obtain any missing approval, by what deadline and at whose cost.
• Allow withdrawal and a full refund if the agreed evidence or authority outcome is not delivered.
• Keep part of the purchase price in escrow where a defined post-completion obligation remains.
• Preserve specific seller representations about approvals, common parts, disputes and authority notices.

A practical stop/go test

• Proceed normally only when the actual state, documents and permitted use reconcile.
• Pause when the path is plausible but evidence is incomplete; obtain written professional and authority input before paying.
• Renegotiate when correction has a quantified cost, delay and residual risk.
• Walk away when the seller refuses documents, the structure or common parts are uncertain, or the contract shifts an undefined legalisation risk to you.

This guide is a decision framework, not a finding that a specific alteration required permission. Requirements depend on the date, nature and impact of the work. Have the actual apartment and historical rules reviewed before signing.