Among them, the part against the Defendant (Counterclaim Plaintiff) and the part against the counterclaim shall be reversed, and this part shall be reversed.

1. According to the reasoning of the first instance judgment cited by the lower court and the reasoning of the lower judgment, the lower court determined as follows.

According to the judgment on the claim of this case, since the changed construction cost of the construction of this case as to the claim of this case was KRW 770 million, and the construction cost paid by the Defendant (Counterclaim Plaintiff, hereinafter “Defendant”) to the Plaintiff (Counterclaim Defendant, hereinafter “Plaintiff”) is KRW 742,884,075, the unpaid construction cost is KRW 27,115,925 (= KRW 777,000,000 - KRW 742,884,075), or according to the appraisal entrustment by the first instance court to the appraiser I company of the first instance, the construction cost presumed to have been incurred for repair due to defects in the part which was not constructed or constructed by the Plaintiff. Accordingly, if the damages claim of the Defendant against the Plaintiff against the Defendant was offset against the damages claim of the Plaintiff, the Defendant is obligated to pay the Plaintiff the unpaid construction cost as the construction cost (=25,925,271,9751,950,000).

B. As to the counterclaim of this case, the Defendant sought compensation of KRW 1,189,00 in lieu of the defect repair recognized by the first instance court on the premise that the Plaintiff paid all the construction cost of this case to the Plaintiff. However, as seen earlier, the Defendant’s counterclaim claim of this case based on the premise that the payment of the construction cost was made in full cannot be accepted.

Even if the defendant's assertion that the sum of the construction cost that the defendant did not bear due to the failure to perform construction or defects includes the amount of KRW 23,691,560, not the amount of KRW 1,189,000 recognized by the first instance court, according to the result of the appraisal entrustment with the first instance court, it would be required to repair it due to the defects that the plaintiff did not perform or constructed.