Building Confirmation, Inspection Certificates, and Unapproved Alterations in Japan

Four versions of the same building must agree

Due diligence on an existing Japanese building should reconcile four versions of the asset: what was approved, what passed completion inspection, what is recorded in the real-property register, and what physically exists. Differences are not automatically fatal. They do, however, affect the questions that an architect, surveyor, judicial scrivener, lender, insurer, and buyer must answer before price and renovation plans can be trusted.

The basic document pair is the building confirmation, kakunin-zumi-shō (確認済証), and inspection certificate, kensa-zumi-shō (検査済証). Building confirmation records that a proposed plan was reviewed under the applicable process before construction. The completion inspection examines the finished work, and the inspection certificate records the result. Historic practices and record availability vary by period and authority, so an older building may require archive research rather than a document in the seller's files.

Obtain documents and administrative history

Ask for the confirmation notice or certificate, approved drawings, completion inspection certificate, structural calculations where applicable, later confirmation records for additions, building register, cadastral or survey material, property-tax records, renovation plans, and contractor records. If original certificates are missing, ask the competent authority what ledger information, archived drawings, certificates of recorded matters, or other evidence can be obtained.

Do not describe a missing inspection certificate as proof that the building is illegal. MLIT's guidance on buildings without an inspection certificate expressly distinguishes the absence of the certificate from an automatic determination that enforcement against an illegal building is required. The correct response is further investigation: establish whether inspection occurred, what records exist, what was built, and whether current or historic compliance can be assessed through an accepted process.

MLIT also publishes a framework for using designated confirmation and inspection bodies to investigate the Building Standards Act compliance status of certain buildings lacking inspection certificates. Whether that route is available or sufficient depends on the building and intended work. The buyer's architect should define the scope before contract rather than promising that missing paperwork can always be cured later.

Compare approved plans with present conditions

Walk the property with plans in hand. Confirm gross floor area, footprint, storeys, use, structure, roof form, balconies, garages, storage rooms, stairways, windows, fire separations, retaining walls, site boundaries, and the relationship to the road. For a condominium, separate changes inside the exclusive-use unit from common-area components and association approvals.

Common discrepancies include enclosed balconies, converted garages, extended rooms, rooftop structures, merged rooms, relocated wet areas, added kitchens, changed use, altered fire doors, removed structural walls, and retaining-wall work. Some changes may have required confirmation or association consent; others may have been permissible maintenance. The buyer needs a professional classification, not a visual guess.

The registered floor area can also differ from marketing area or physical measurement for legitimate reasons. Condominium wall-centre area and registry internal-wall area are not the same measure. A discrepancy becomes a diligence issue when the source and method cannot be explained, or when the physical building includes space that appears absent from approval and registry records.

An inspection does not certify legal compliance

Japan's existing-home building condition survey, tatemono jōkyō chōsa (建物状況調査), is performed by an architect who has completed the registered existing-home survey training and follows the prescribed survey method. It examines visible conditions in major structural and water-intrusion-related components. It is useful, but MLIT's transaction guidance warns that it does not determine the existence of every defect.

The survey also has a different job from a compliance investigation. A wall may appear dry and sound but still be an unapproved alteration. Conversely, a properly approved building can have serious deterioration. Commission the physical survey and the document/compliance review as complementary scopes, and state in writing who is checking structure, water ingress, termites, equipment, legal records, additions, and intended renovation.

Third parties may apply different tests to the same discrepancy. A lender may decline collateral, require more evidence, or reduce value. An insurer may ask about use, construction, or undisclosed work. A future buyer may demand regularisation even where the present buyer accepted uncertainty. Record the architect's view, the lender's written position, the association approval record, and any insurance condition relevant to the intended use.

If regularisation is proposed, define what that word means. It may involve reconstructing records, applying for a change, removing work, completing safety work, or only obtaining a professional report; these are not equivalent. Put the action, responsible party, cost allowance, authority confirmation, and deadline into the contract instead of relying on a promise to sort it out later.

Keep every answer in writing.

Why lenders and renovation plans care

A lender may require acceptable evidence of the building's legal status, marketability, remaining life, access, structure, and insurance. Published lending criteria do not eliminate property review. A building with unclear additions or a missing inspection history may receive a lower valuation, additional conditions, a reduced term, or no offer from a particular lender. That is lender policy, not a universal legal conclusion.

Renovation can expose the issue more directly. A project involving structural work, a change of use, extension, major repair, or major alteration may require confirmation or a review of existing compliance. If the present condition cannot be documented, the architect may first need measurements, archive research, opening-up work, or a compliance-status investigation. Budgeting only for finishes can therefore understate both cost and programme.

Worked scenario: the enclosed garage

Consider a registered 110-square-metre wooden house marketed as approximately 128 square metres after a garage was enclosed as a bedroom. The seller says the work was completed fifteen years earlier. The registry, original confirmation drawing, and property-tax record do not immediately agree on the added area, and no later confirmation record is supplied.

The correct analysis is not “the extra 18 square metres are free” or “the entire house is illegal.” The buyer asks an architect to confirm whether the enclosure required approval, whether site coverage and floor-area limits remain satisfied, whether structure and fire provisions were affected, and what evidence or corrective work would be needed. The judicial scrivener checks registration implications, the lender reviews acceptability, and the contract addresses the discrepancy. Until those answers exist, the extra room should not receive the same value as fully documented floor area.

Compliance review checklist

• Obtain original and later confirmation and inspection records.
• Retrieve available authority ledger records where certificates are missing.
• Compare approved drawings, registry, tax records, listing area, and measured condition.
• Identify additions, enclosures, changes of use, structural changes, and retaining-wall work.
• Separate physical inspection from legal/compliance investigation.
• Confirm condominium association approval for unit alterations where relevant.
• Ask the architect what future renovation would require and whether existing status creates extra work.
• Ask the lender to review the actual records rather than a verbal description.
• Price undocumented floor area conservatively until it is resolved.
• Put required evidence, correction, or termination rights into the contract where material.

Primary sources

• MLIT — Existing building use and guidance for buildings without inspection certificates: https://www.mlit.go.jp/jutakukentiku/jutakukentiku_house_fr_000061.html
• MLIT — Existing-home building condition surveys in real-estate transactions: https://www.mlit.go.jp/tochi_fudousan_kensetsugyo/const/tochi_fudousan_kensetsugyo_const_tk3_000001_00063.html
• MLIT — Existing-home survey technician system and survey standards: https://www.mlit.go.jp/jutakukentiku/house/kisonjutakuinspection.html
• MLIT — Existing-home condition survey summary: https://www.mlit.go.jp/jutakukentiku/house/content/001849549.pdf
• MLIT — Designated confirmation and inspection bodies: https://www.mlit.go.jp/jutakukentiku/house/jutakukentiku_house_tk_000019.html

Reviewed against the linked primary sources on 23 August 2026. A property-specific architect and competent authority must determine the relevant historical and current compliance position.