The judgment below is reversed, and the case is remanded to Seoul High Court.

The grounds of appeal are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed).

In the case of the extension of a building, not only the physical structure attached to the existing building, but also whether the extended part can be an independent economic utility from the existing building in terms of its use and function, and the intention of its owner, etc. shall be determined by comprehensively taking into account whether the extended part can be an independent object of ownership in the transaction.

(1) On June 10, 194, the Plaintiff, who is the owner of a house and neighborhood living facilities (hereinafter referred to as the “main building of this case”) 98/252 shares in Mapo-gu Seoul Mapo-gu B and 827.5 square meters (hereinafter referred to as the “instant site”) and the second floor above the said ground, leased the building to D on July 10, 2002. The Defendant, on March 15, 2010, linked to the left side of the main building of this case to the front floor and the rear side of a wooden roof for a long time (hereinafter referred to as “the instant violating building”) and discovered the extension of the building to the left side of the building of this case, including the building of this case, the extension of the building of this case to the left side of the house of this case, can be seen as the extension of the building of this case, and the building of this case to the left side of the house of this case, including the building of this case.

Examining these facts in light of the above legal principles.