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When cracks keep appearing in walls and water keeps leaking from ceilings after moving in, residents begin to consider a defect lawsuit. What often decides the outcome is not how severe the defects are, but when, against whom, and how the claim is made.

This article uses statutes and recent Supreme Court decisions to answer the three questions covered in the video: how the periods differ by type of defect and when they start, how the consent rate for a lawsuit is calculated when there are many unsold units, and whether a fire door that looks fine can still be defective.

[Contents]

1. Whom to Claim Against, and What to Claim

2. Periods Differ by Type of Defect – 10, 5, 3 and 2 Years

3. When the Period Starts – Exclusive Units and Common Areas

4. Even With Many Unsold Units – The Developer's Exclusion From Voting and Ratification

5. A Fire Door That Looks Fine Can Still Be Defective

Whom to Claim Against, and What to Claim

The person who built and sold a multi-unit building (the developer, 분양자) and the contractor who built it under a contract with the developer bear warranty liability to unit owners, and the Civil Act's provisions on a contractor's warranty liability apply mutatis mutandis (Article 9(1) of the Act on the Ownership and Management of Multi-Unit Buildings (집합건물법)). Residents may therefore demand that the defects be repaired, or claim damages equal to the cost of repair. In litigation, the repair cost for each defect item is usually assessed through a court-appointed appraisal and awarded in money.

You also need to decide whom to sue. Among the contractor's warranty liabilities, liability for damages arises only if the developer has applied for rehabilitation or bankruptcy, has been dissolved, is insolvent, or the like (Article 9(3) of the same Act). In principle, damages are claimed from the developer, and from the contractor only if the developer is in financial difficulty. Special agreements on the developer's and contractor's warranty liability that are less favorable to buyers than the law are invalid (Article 9(4)).

Because the damages claims in principle belong to each unit owner, in practice the council of resident representatives or the management body takes assignments of the claims from each unit and brings a single lawsuit. This assignment procedure is covered in detail in Can an Apartment Residents' Council Sue the Builder Directly for Damages? (Korean).

Periods Differ by Type of Defect – 10, 5, 3 and 2 Years

The Multi-Unit Buildings Act requires unit owners to exercise their warranty rights within periods set by type of defect (Article 9-2(1) of the Act and Article 5 of its Enforcement Decree).

• 10 years: defects in the main structural parts of the building, such as columns and walls, and in ground work

• 5 years: structural or safety defects, such as in site preparation, reinforced concrete, steel frame, masonry, and roofing and waterproofing work (also 5 years for defects that arose before the start date)

• 3 years: functional or aesthetic defects, such as in building equipment, carpentry, windows and doors, and landscaping work

• 2 years: defects that are easy to find, replace and repair, such as in finishing work

Apartments are separately governed by the Multi-Family Housing Management Act (공동주택관리법). Defects in load-bearing structural parts carry a 10-year period, and the warranty periods for other defects are set by type of facility work in an annex to the Enforcement Decree (Article 36(3) of the Act and Article 36(1) of its Enforcement Decree). The Act defines a defect as a flaw such as cracking, settlement, breakage, lifting or leakage caused by faulty construction, serious enough to impair safety, function or appearance (Article 36(4) of the same Act).

In practice, residents first request an appraisal of every item that appears to be a defect, and once the appraisal report is issued, the parties dispute which type of work each item belongs to and whether it falls within the period. Even the same leak may be subject to a different period depending on whether it is a waterproofing defect or an equipment defect.

When the Period Starts – Exclusive Units and Common Areas

When the period starts differs by part of the building (Article 9-2(2) of the Multi-Unit Buildings Act and Article 36(3) of the Multi-Family Housing Management Act).

• Exclusive units (inside each unit): the date of delivery to the unit owner (resident)

• Common areas (exterior walls, underground parking, stairwells, etc.): the date of use inspection or use approval (or the date of temporary use approval or building-by-building use inspection, if obtained)

Because the period for common areas runs from the use inspection date, which comes before move-in, part of the period may already have passed by the time residents move in. Also, if a building is destroyed or damaged because of a defect, the right must be exercised within one year from that date (Article 9-2(3) of the Multi-Unit Buildings Act). If you discover a defect, it is important not to delay, to keep records and to exercise your rights.

Even With Many Unsold Units – The Developer's Exclusion From Voting and Ratification

For a management body, such as that of an officetel, to sue, a resolution of the management body meeting is required. Unless otherwise provided, meeting decisions are made by a majority of unit owners and a majority of voting rights (Article 38(1) of the Multi-Unit Buildings Act), and if at least three-quarters of unit owners and of voting rights agree in writing or electronically without holding a meeting, a resolution is deemed to have been passed (Article 41(1) of the same Act).

The problem is unsold units. If the developer still owns unsold units, the developer is also a member of the management body, so with many unsold units it may seem hard to reach the required consent rate. The Supreme Court held that in such a case the developer holds both the status of a unit owner and that of the party liable for warranty, but since warranty liability is a matter in which the developer has an interest as the liable party, the developer has no voting right on an agenda item seeking to hold it liable for defects. Therefore, the resolution requirements must be calculated excluding the unsold units owned by the developer from the number of unit owners and the voting-right ratio (Supreme Court Decision 2025Da213134, December 4, 2025).

In that case, the management body first filed suit in 2018 and then ratified the filing by obtaining written resolutions between 2024 and 2025; because the written resolution requirement was met once the unsold units were excluded, the filing was held to have been validly ratified. This means there is no need to give up on a lawsuit simply because the consent rate appears insufficient.

A Fire Door That Looks Fine Can Still Be Defective

Facilities whose performance standards are set by law, such as fire doors, are defective if they fall short of that performance even if they look fine. The Supreme Court held that because the push side and pull side of a fire door form a single unit, both sides must meet the performance required by building laws; because their structures differ, for example in handles and locks, which can affect test results, each side must be tested separately; and a fire door must be regarded as defective even if only one side falls short (Supreme Court Decision 2025Da211105, October 16, 2025).

The same decision held that calculating the defect rate by judging pass or fail per set arbitrarily assembled for testing is hard to adopt, because results vary greatly depending on how the sets are composed. Instead, it said one could consider multiplying the pass rates of the push side and pull side to find the rate at which both sides are free of defects and subtracting that from 100%, and it reversed the lower court, which had evaluated the two sides separately. The scope of fire door appraisals and replacement costs is covered in Fire Door and Floor Noise Defects.

In short, preparing an apartment defect lawsuit means first checking the period and start date for each type of defect, then deciding whom to claim against and for what between the developer and the contractor, and then completing procedures such as claim assignments and resolutions. Even with many unsold units, or after a suit has already been filed, the resolution requirements can be recalculated under the Supreme Court's decision.

Cheongchul Law Firm directly handles apartment and officetel defect lawsuits and construction disputes. If defects keep recurring, please contact us through consultation booking before the periods expire.

This post is written for the purpose of providing legal information and does not constitute legal advice on any specific matter. Since conclusions may differ depending on the facts of each case, please be sure to consult a professional.