A. The F Co., Ltd. (hereinafter referred to as “F”) contracted the instant construction work for machinery and equipment (hereinafter referred to as “the instant construction work”) among the construction work of the instant officetel in size of H and 1 stories above ground and 8 stories above ground (hereinafter referred to as “officetel”) in Jeju-si, which was implemented by G (hereinafter referred to as “G”) as the owner of the building, and subcontracted the said construction work to the Plaintiff on January 2018.

B. On October 2017, the Plaintiff awarded a contract for the installation of water tank (hereinafter “instant installation”) to Defendant B by setting the construction cost of KRW 16,500,000, and Defendant B completed the installation work by receiving materials from Defendant D Co., Ltd. (hereinafter “Defendant Company”); and the Plaintiff paid the construction cost on December 7, 2017.

C. As to the instant officetel, approval for use was granted on January 19, 2018.

G notified F of the fact that the water tank (hereinafter “water tank in this case”) was defective, and F notified the Plaintiff, and the Plaintiff again notified the Defendant B of the defect.

As a result of the confirmation by Defendant B, it knew that there is a problem in the materials used to install a water tank, and requested the Defendant Company to repair the defects.

On the other hand, the Defendant Company supplied materials to the Defendant Company was the Defendant Company I (hereinafter “I”), and Defendant B and I discussed the repair method, and performed the instant water tank repair work (hereinafter “instant repair work”). On November 6, 2018, the instant repair work was carried out in the order of the Defendant Company’s employees to re-take water into the water tank after all water of the water tank and repair the defective part.

After construction, the personnel of I leave the construction site without confirming the operation of safety devices (hereinafter referred to as the “safety devices of this case”) that make water not to flow out in the water tank if water is fully stored.

E. After the instant repair project, the water tank of this case exceeded the water level.