1. The plaintiff's appeal is dismissed.

2. The costs of appeal shall be borne by the Plaintiff.

The purport of the claim and appeal is the purport of the appeal.

1. Basic facts

A. The plaintiff is a corporation whose main business purpose is the fire fighting construction, and the defendant is the owner of multi-family housing and new construction of business facilities on the land outside the Busan Suwon-gu B.

B. Around May 2015, the Plaintiff entered into a contract with the Defendant to implement fire-fighting system installation works (hereinafter “instant construction works”) among the new construction works (including value-added tax of KRW 165 million) (hereinafter “instant construction contract”).

C. After that, the Plaintiff completed the instant construction, and on February 2, 2016, the Defendant paid KRW 16.5 million to the Plaintiff on five occasions between September 9, 2016 and September 9, 2016, both the construction cost of KRW 165 million.

On the other hand, the construction of this case partially changed or added the detailed construction details during the process, and there is some difference between the permit drawings and the completion drawings of the construction of this case.

[Ground of recognition] Facts without dispute, Gap evidence 4, 5 evidence, Eul evidence 2 to 5 (including the number of each branch), the purport of the whole pleadings

2. Summary of the parties' arguments

A. The gist of the Plaintiff’s assertion 1) The Plaintiff, the primary cause of the instant fire-fighting project, while carrying out the instant fire-fighting project, shall receive additional construction cost from the Defendant, and further construction works, such as machinery, electricity, fire-fighting supervision, T.A.B. Inspection, etc. (hereinafter “instant additional construction”).

Upon completion, the Defendant is obligated to pay the additional construction cost of KRW 18 million (excluding value-added tax) and the delay damages thereof. 2) Even if the said additional construction cost is not recognized, the fire supervision portion of the instant additional construction work and the part of the T.A.B. Inspection shall be borne by the Defendant, the owner of the building. Therefore, the Defendant is obligated to return the said additional construction cost of KRW 5 million and the total of KRW 6.5 million (excluding value-added tax) and the delay damages to the Plaintiff as unjust enrichment.

B. Summary of the Defendant’s assertion