If you look carefully at the house, you will find that there are some floors, such as 6th, 11th, 18th, and 26th and 33th floors.
In the 10th year after the mid-1980s, there were many 6-story residential buildings. This is because the "Design Code for Residential Buildings" promulgated in 1985 stipulated that residences above the 7th floor must be equipped with elevators. The 6-story residential building does not need to be equipped with an elevator, and can maximize the utilization of land, which has become the best choice for developers. Compared with the 4th and 5th floor public houses built in the 1950s, the 6th floor residential building has more people and it is more difficult to evacuate in the event of a fire. It looks safer.
But after the mid-1990s, houses without elevators became increasingly unpopular. Since it is necessary to install an elevator, it is in the developer's interest to build the building higher. However, according to the "Code for Fire Protection in Architectural Design": developers need to install indoor fire hydrants for residential buildings with more than 7 floors. You will find that the developer will not let the residence exceed 11 floors, because residential buildings above 12 floors must have closed stairwells, which is the main reason for many of the existing residential buildings on 11 floors.
When it comes to building higher-rise residential buildings, developers like to choose 18 floors. Because it is necessary to set up smoke-proof staircases above the 19th floor, the cost is higher. If you want to build a higher residential building, the 26th floor is one of the two best floors. This is not a consideration of fire prevention requirements, but a combination of the floor area ratio, height limit, and coverage requirements. . Another best floor to choose from the fire protection requirements is the 33rd floor. The 33-storey house is more than 90 meters high, and no refuge floor is required according to specifications. Refuge floors must be provided for high-rise residences over 100 meters, and the investment of developers is very large. Therefore, in domestic high-rise residential buildings, you can hardly see 35- and 36-story houses with a height of 100 meters. In places where the land price is particularly high, it is more cost-effective to build a residential building that is a few hundred meters high.
After the implementation of the 2014 version of the Code for Fire Protection in Building Design, the situation will change. For example, the 11-story building will decrease, and the 9-story building will slowly increase. The higher the floor, the more difficult it is for residents to evacuate during a fire. This is why the fire protection code for building design has different fire protection requirements for residential buildings on different floors.