According to Gu, the restoration of protected buildings is nothing like constructing a new one as special preparation must be made. For example, the sand used to restore protected buildings must be filtered two more times than usual to make it suitable for the old structures.

The bricks have to be custom-made, too.

Gu says three types of bricks need to be smashed and mixed to form new bricks that are of similar color and quality to the original.

One of the most arduous projects undertaken by the company in recent times is the restoration of a garden residence at 63 Kangping Road, which is located within the zone. Built in the 1940s, this three-story house, with semi-circular balconies on each floor and a red brick facade, has been designated a cultural relic. To restore the building, the team at Shanghai Xufang had to do research on the original style of the structure and scour for the right materials that would allow the house to retain its look.

"The building had fallen into disrepair over the years due to poor management and human activities that left behind fragile windows and walls that had trouble keeping wind and water out," says Yue Jiayong, deputy manager of the restoration department of the company.

"As we weren't able to find ceramic tiles that are of the same size and material as those used on the walls of the kitchen, we had to purchase similar ones before cutting them into smaller pieces," says Zhu Yucheng, head of the Kangping Road project.

The windows were a challenge to replace as well. Zhu says the team took about three months just to manufacture more than 5,800 square meters of similar windows for the house as most of the handles on the previous ones had decayed beyond repair. While retaining the original look of the building was important, Gu and his team nonetheless had to introduce new elements required today.