1. The plaintiff's appeal, the plaintiff's claim extended by this court, and the defendant's appeal are all dismissed.

2...

1. The reasons why the court accepted the judgment of the court of first instance as to this case are cited by the main sentence of Article 420 of the Civil Procedure Act, since the following judgments are identical to the reasons of the judgment of the court of first instance, except for the addition to the corresponding part.

[Additional Determinations] The Plaintiff asserts to the effect that “The Plaintiff’s construction cost was assessed as KRW 158,961,00,000 according to the results of the appraisal conducted by this court, and the Defendant is obligated to additionally pay KRW 103,961,00,000, deducting the construction cost as recognized by the lower court from KRW 158,961,00.”

However, the plaintiff's above assertion cannot be accepted for the following reasons.

(1) The construction cost under a contract for construction works shall, except in extenuating circumstances, be determined according to an agreement between the parties, and shall not be deemed determined according to the result of appraisal after the completion of the construction works.

Meanwhile, there is no evidence suggesting that the Plaintiff and the Defendant agreed to pay the construction cost on the basis of the evaluation results after the completion of construction works without separately stipulating the construction cost when concluding the instant subcontract.

② Even if the contractor completed the construction work in excess of the agreed construction cost, it is not possible to seek additional payment of the construction cost against the contractor, unless there are special circumstances, such as the agreement on the payment of additional construction cost.

However, in the instant case, no evidence exists to deem that there was an agreement between the Plaintiff and the Defendant on the payment of additional construction cost.

(3) Even if the contractor paid the expenses in excess of the agreed construction cost and performed the construction work, the contractor cannot be deemed to have the obligation to reimburse the amount equivalent to the expenses in accordance with the legal doctrine of unjust enrichment, etc. on the sole basis

2. The judgment of the court of first instance is the conclusion.