1. As to the additional construction cost of the remainder of the construction, excluding the part of the volatilen Center

A. As to the grounds of appeal on whether to permit the claim for additional construction cost

According to the reasoning of the judgment below, in the contract documents related to the second construction contract of this case, the court below seems to have scheduled the adjustment of the construction cost in principle by providing various provisions on the premise of adjustment of the construction cost when the second construction contract of this case is later modified, while the contract documents are required for the function. or at the request of the defendant, the provision that does not allow an increase or decrease of the construction cost in the case of "a modification of designs at the request of the defendant" [Article 9 and 11 of the Special Conditions for the Construction Contract, Section 11 of the Special Conditions for the site site Agreement, Section 3-3 of the Special Specifications is not only in an organic relationship as long as the original and additional construction work can be evaluated as integrated into functional aspect, but also in the aspect of cost and effort, the court below's determination is just in light of the legal principles as to additional construction work, or in light of the principle of free evaluation of evidence, as alleged in the ground of appeal.

B. As to the ground of appeal on the scope of additional construction cost

1) According to the reasoning of the judgment below, at the time of bidding for the instant construction contract based on evidence, the court below accepted the additional labor cost of the instant construction project from the Defendant for each process along with the shop design drawings of October 2006 for the said construction project. The unit price of the materials is recorded in advance and the unit price of the materials is recorded in public column. The unit price of the materials is stated in advance and the unit price of the labor cost is stated in public column, and the cost of the additional labor cost is calculated as KRW 74,628,619,00 by supplementing the estimated unit price of the materials and the quantity of the labor cost of the instant construction project, and then calculated as KRW 527,619,00 for the additional labor cost of the instant construction project as stated in the standard construction cost. The court below found that the additional labor cost of the instant construction project and the additional construction cost of the instant construction project are calculated as stated in the calculation of the unit price of the construction work and the additional construction cost of the instant construction project as stated in the standard construction cost of the instant construction work cost.

2) However, the lower court’s determination is difficult to accept for the following reasons.

According to the reasoning of the judgment below and the records, the special term specifications, one of the contract documents for the second construction project in this case, which are the increased or decreased construction volume, shall be the unit price specified in the contract statement, and the unit price for a new expense without the contract unit shall be settled by the amount calculated by multiplying the contract unit price by the successful tender rate calculated as at the time of the time of the contract. In light of all the circumstances revealed in the records, such as the language and text of the above provision, the background leading up to the determination of the construction price for the second construction project in this case, and the process leading up to the conclusion of the contract, etc., the term "the increased or decreased construction volume" in the former part of the above provision shall be the unit price specified in the contract statement, in the case of an additional construction project with the increased or decreased construction volume, shall be the same as the standard for calculating the unit price for the second construction project in this case. Thus, the plaintiff and the defendant reached such agreement with regard to the calculation of the additional construction cost.

Meanwhile, according to the records, each of the above "the details of additional construction works", which the court below recognized as an additional construction work, is not a new construction work, but a construction work under the second construction contract of this case is added in quantity or additionally added materials or labor necessary for the construction work. Thus, the additional construction work under the above "the details of the additional construction work" constitutes an increase in quantity of construction work. Accordingly, the additional construction cost should be calculated on the same basis as the unit price calculation criteria in the details of the second construction contract of this case, which correspond to the details of the second construction contract of this case, and the same applies to the calculation of labor cost out of the additional construction cost.

However, as seen earlier, the labor cost among the instant BM details was determined by the Defendant’s prior entry of the labor cost in each process and the Plaintiff entered the quantity of labor. As such, in calculating the labor cost among the additional construction cost, the labor cost should be the same as the labor cost stated in the instant BM details, and the labor cost should be based on the same standard as the labor cost stated in the instant BM details. According to the records, the Plaintiff offered labor cost by stating the labor cost in the instant BM details, without complying with other objective standards, the anticipated labor cost is below the amount of labor cost calculated based on the standard labor cost per se. Thus, the Plaintiff’s additional labor cost should also be calculated based on the same standard as the labor cost, if it is based on a certain standard in the instant BM details by itself, and if it is not clear, it is reasonable to calculate the additional labor cost based on the objective labor cost, such as the labor cost per each process of construction work, and then, to apply the aforementioned ratio to the said additional labor cost calculated based on the objective labor cost per se.

3) Nevertheless, the lower court deemed that there was no agreement between the Plaintiff and the Defendant on the calculation method of the additional construction cost, and concluded the second construction contract in this case, it calculated the amount of labor as it is based on the standard pumsem that the Plaintiff and the Defendant did not take as the basis for the calculation of the amount of labor. In so determining, the lower court erred by exceeding the bounds of the principle of free evaluation of evidence in violation of logical and empirical rules, and by misapprehending the legal doctrine on

C. As to the allegation in the grounds of appeal on whether to alter minor construction works, the lower court determined that additional construction works implemented by the Plaintiff could not be deemed minor construction works based on the amount of labor calculated illegally as seen earlier. As such, the lower court’s determination on minor construction works could not be maintained.

2. As to the additional construction cost of the volatilen Center

A. Based on its adopted evidence, the lower court acknowledged the portion of the construction cost that the Plaintiff and the Defendant agreed to the construction cost as the total material cost, 28,945,329 won, total labor cost, 17,759,700 won, total labor cost, 46,704,329, total labor cost, 329, total labor cost, and total labor cost, without separately stipulating detailed material volume, material unit cost, labor cost, and labor cost.

나아가 원심은, 이 사건 제2차 공사계약 당시 휘트니스센터 부분 전기공사는 설계도면에 누락되어 있었기 떄문에 위와 같이 약정된 공사대금은 정확한 공사비가 아닌 대략적으로 개산한 공사비에 불과하고 이후 설계도면의 확정에 따른 신규 내지 추가공사의 시행과 그에 대한 공사비의 추가정산이 예정되어 있었던 것으로 보인다는 등의 이유로 원고가 피고에게 휘트니스센터 부분에 관한 추가공사대금을 청구할 수 있다고 보면서, 원심 감정인 C의 감정 결과 및 보완감정 결과에 따라 준공 시를 기준으로 하여 실제 투입된 자재수량과 자재단가에 따라 재료비를 산출하고, 위 자재 설치를 위한 노무수량은 표준품셈을 기준으로 하여, 노무단가는 이 사건 제2차 공사계약 당시 정해진 노무단가를 기준으로 하여 노무비를 산출함으로써, 완공된 휘트니스센터 부분의 공사비를 재료비 19,347,321원, 노무비 92,513,411원 합계 111,860,732원으로 산정한 후, 여기에서 이 사건 제2차 공사계약 당시 약정한 공사비 46,704,329원을 공제한 금액이 그대로 휘트니스센터 부분 추가공사대금으로 인정된다고 판단하였다.

B. However, such determination by the lower court is difficult to accept for the following reasons. According to the foregoing factual basis, the Plaintiff and the Defendant concluded a detailed work process with respect to other parts of the construction contract at the time of the conclusion of the second construction contract, and accordingly, agreed on the construction cost by specifying the material cost and labor cost for each process, as stated in the instant BM details. On the other hand, it is difficult to find out the difference between the Plaintiff and the original construction cost and the original construction cost and the original construction cost to the extent that the agreed upon by the appraisal center’s agreement on the total construction cost and the total construction cost were 46,704,329,00 won, regardless of the difference between the original construction cost and the original construction cost’s construction cost and the original construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction work cost’s construction cost’s construction cost’s construction cost’s construction cost’s construction cost’s new construction work cost’s construction cost’s conclusion.

3. As to the waiver of the claim for additional construction cost

Examining the reasoning of the judgment below in light of the relevant legal principles and records, it is reasonable and acceptable to dismiss the Defendant’s assertion that the Plaintiff renounced the claim for additional construction cost when concluding a modified contract on the second construction of this case on the ground that it is difficult to recognize that the Plaintiff renounced the claim for additional construction cost, and contrary to the allegations in the grounds of appeal, there is no error of law

4. Conclusion

Therefore, without further proceeding to decide on the remaining grounds of appeal, the part against the defendant among the judgment below is reversed, and the case is remanded to the court below. It is so decided as per Disposition by the assent of all participating Justices on the bench

Justices Kim Yong-deok

The Chief Justice Park Jae-young

Justices Kim Gin-young