A. On December 31, 2013, the Defendant entered into a contract with 15 members of the reconstruction association, including Plaintiff A, for the re-building and re-building of H-building on the ground of 958 square meters in Dongdaemun-gu Seoul, Dongdaemun-gu, Seoul, and newly constructed three units of housing on the above ground (hereinafter “instant housing”) with 3 units of 6 units on the above ground. Of the instant housing, the remainder of the housing units, excluding the share of members, was sold to the general public and appropriated

B. The Defendant newly constructed the instant house and sold it with the household units on the sixth floor, which is the first upper floor of each consent (hereinafter “the instant multi-story”) and with the household units on the sixth floor. In addition, the Defendant constructed a separate entrance to the instant multi-story from the central stairs, and built it as an independent household that prevents outside persons from entering the instant multi-story.

C. Plaintiff B purchased the purchase price of KRW 345 million, along with the multi-story 602, KRW 101,000, KRW 3200,000,000, KRW 102,601, and KRW 102,000,000, KRW 3900,000,000, KRW 102,0000, KRW 602, and KRW 102,000, KRW 103,601, and KRW 295,000,000, KRW 103,602, and KRW 285,000,000,000, KRW 101,000 as reconstruction members, KRW 101,000,000, KRW 1000,000,00,000.

(hereinafter, the above sales contract or sales contract is collectively referred to as "the sales contract of this case".

However, around April 20, 2015, the Plaintiffs received notification from the head of Dongdaemun-gu Office that the entry into the rooftop necessary for escape and fire extinguishing was voluntarily corrected on the ground that they violated Article 49 of the Building Act and Article 41 of the Enforcement Decree of the Building Act, and that if they did not correct it, they would be scheduled to take administrative measures, such as registering the building as a non-compliant building and imposing a non-performance penalty.