1. The judgment of the court of first instance is modified as follows.

The Defendant-Counterclaim Plaintiff (Counterclaim Plaintiff), 1) Plaintiff (Counterclaim Defendant 53,931.

The principal lawsuit and counterclaim shall be judged together.

1. Basic facts

A. Around September 8, 2011, the Defendant had contracted the construction of the new building B in Seongdong-gu Seoul (hereinafter “instant new construction”) with A to perform the construction work.

On April 2012, soil gates constructed for underground installation have been flooded from part of the wall, and the underground part has been flooded, resulting in a safety problem for the construction site and surrounding buildings.

The defendant prevented the flow of groundwater into the construction site of this case, and performed the ground reinforcement work for neighboring buildings.

B. On June 15, 2012, the Defendant entered into a contract on the ground reinforcement works of an adjacent building (hereinafter “instant ground reinforcement works”) with the Plaintiff on June 15, 2012 and the land adjacent to the instant new construction site (hereinafter “instant new construction site”).

2) On October 30, 2012 and December 7, 2012, the Plaintiff and the Defendant concluded a contract to set the construction cost of KRW 110,000,000, and thereafter, concluded a modified contract regarding this contract on two occasions on October 30, 2012, and finally increased the construction cost of KRW 143,00,000 at the initial KRW 110,000.

The contents of the final final and conclusive construction works shall be conducted on three parcels of Seongdong-gu Seoul Metropolitan Government, D and E (hereinafter referred to as “C land, D” and “E”) adjacent to the site of the new construction of this case, and the calculation details of the construction cost shall be as follows:

Section 6,25,147,800 of land D 73,150,800 E and 17,722,000 of land D 125,147,800 of indirect construction cost 6,257,390 of 5% of direct construction cost -1,405,190 of supply value of 130,000 = 131,405,190 of -1,400 of 131,405,190 of -1,400 of -1,405,190 of -1,405,190 of the final construction cost of KRW 143,00,000 of value-added tax of KRW 143,00,000 of the final construction cost of KRW

C. On September 14, 2012, the Defendant entered into a contract for the reinforcement of a household facility, and the new construction of this case, which is located in the Plaintiff and the new construction of this case.