1. All appeals filed by the Defendant (Counterclaim Plaintiff) are dismissed.

2. The preliminary counterclaim added at the trial is dismissed.

A principal lawsuit and a counterclaim shall be deemed simultaneously.

1. Basic facts

A. The Plaintiff is the owner of the Dongjak-gu Seoul Metropolitan Government D Apartment (hereinafter “instant apartment”) 702, and the Defendant is the owner of the instant apartment.

B. On July 14, 2014, C et al. sent a large quantity of water to the excellent pipes during the process of cleaning the water tank on the instant apartment rooftop. As the excellent pipes set forth in 802 of the instant apartment complex failed to prevent water from falling, it was flooded that the instant apartment complex was flooded. Accordingly, water leakage was also generated in the ceiling set forth in 702 of the instant apartment complex.

(hereinafter referred to as “instant accident”). C.

At the time of the instant accident, the balcony was extended to 802, and it was surrounded by a joint board around the superior.

From July 2010 to July 2013, the Plaintiff served as the representative of the instant apartment occupants.

E. The construction cost for the restoration of the instant apartment No. 802 due to the instant accident is KRW 3,910,495, and the construction cost for the restoration of the instant apartment No. 702 is KRW 12,047,827.

[Reasons for Recognition] Unsatisfy, Gap evidence Nos. 1, 2, 3, 5, 7, Eul evidence Nos. 1, 4, and 6 (including additional numbers), the appraisal result of the party appraiser E, the purport of the whole pleadings

2. As to the principal lawsuit

A. 1) The basis for liability is that an accident caused by a defect in the installation or preservation of a structure does not mean that only the defect in the installation or preservation of the structure causes the occurrence of the damage, and even if the damage is caused in concurrence with the act of another party or the act of the victim, the damage is deemed to have occurred due to the defect in the installation or preservation of the structure as long as the defect in the installation or preservation of the structure becomes one of the joint causes (see, e.g., Supreme Court Decision 2007Da10139, Jun. 28, 2007). 2) In the above legal principle, the accident in this case is examined as to this case, and whether the accident in this case prevents the excellent manager while cleaning the apartment rooftop tank in this case.