The common numbers of floors in high-rise residential buildings include 11 floors, 18 floors, 26 floors, 33 floors, etc. How are these numbers determined? In addition, there must be a passenger elevator above the 7th floor. Why is it the 7th floor, not the 6th or 8th floor?
What is the basis for determining the common number of floors in high-rise residential buildings?
Answer 1:
11 floors: above the 7th floor, there must be a passenger elevator. There must be a fire elevator above, and the fire doors must reach Class B. Therefore, the only way to earn more and spend less is to build 11 floors (the 7 floors without elevators are mostly school dormitory floors).
18th floor: Safety exits are required starting from the 11th floor, and two are required above the 18th floor, and the stairwells on the 11th to 18th floors must be designed to be closed. So making money, spending less money, and having less trouble is the 18th floor.
Floor 26: Starting from the 19th floor, it is a Class I fire-resistant building (it was Class II before), with two fire-resistant elevators (it is also said that there are three elevators and one fire-resistant) and two smoke-proof staircases. .
Many fast-developing cities now have residential height restrictions, such as 80 meters (airport height restrictions, microwave channels, city skyline control, and city planning requirements). 80/3=26 floors, so it is the number of floors that satisfies residential restrictions and maximizes benefits at the same time.
Level 33: What about those without the above restrictions? What about further up? Counting 3 meters per floor, my country's "General Principles of Civil Building Design" stipulates that when the building height exceeds 100m, both residential and public buildings are super high-rise buildings. (Foreign countries must meet the requirement of more than 40 floors). The 33rd floor is over 100 meters higher, which is another standard in terms of regulations and safety. Therefore, the place where you can make more money with less trouble is the 33rd floor.
Answer 2:
The dividing point for determining the number of floors of a building comes from many sources. There are requirements for urban planning indicators and environmental impact, requirements for considering human physiological factors, fire protection factors, and structural factors.
1. Restrictions of urban planning
First of all, the height of buildings in the city is controlled by urban planning. For example, if planning conditions require multi-story buildings, you cannot build dormitories above seven floors. The planning requires the height to be controlled below 100 meters, so the design will probably be around 30 floors. If you have a house to the north, 50 meters away, and according to the 1:1 sun spacing requirement in the south, your height cannot exceed 50 meters, and you can probably build 16 floors. If it is in the north, assuming the sunshine distance is 1:1.2, then you can only build 13 floors rounded up to 50/3.1/1.2. In addition, land prices are now high, and developers will try their best to obtain higher floor area ratios and salable areas, which has also led to the height of residential buildings getting higher and higher. From the perspective of economic interests, the floor area ratio index of the land is the decisive factor in determining the number of building floors.
2. Human physiological condition
This mainly affects the dividing point between multi-layer and high-level. Multi-storey buildings do not need elevators. Therefore, taking into account the physical limitations of people climbing stairs, if the residence exceeds seven floors, an elevator must be installed, and the height of the railing should be higher than one meter to ensure safety. Dormitories are above seven floors, and offices above five floors require elevators.
3. Fire protection facilities factors
This is the condition that has the greatest impact on the critical point of the number of floors of high-rise residential buildings. Simply put, it is the physical strength of the firefighter and the height of the ladder truck that determine the common story relationship in residential buildings.
There are two important principles for fire protection to ensure the fire safety of buildings: First, ensure the safe evacuation of personnel, which is generally ensured by two-way evacuation. In this way, if a fire breaks out, there will always be someone who can escape. The second is that fire-fighting facilities can ensure firefighters put out fires. In fact, there is another principle, which is to take fire prevention measures, reduce flammable materials, and prevent the spread of fire. But it has little to do with the topic, so I won’t go into details.
The fire extinguishing facilities of the fire brigade in the city are based on fire trucks (ladder trucks for rescuing people) outdoors and fire hydrants indoors. Then the limits of firefighters and fire trucks determine the height limit for high-rise buildings. After experiments, firefighters in full gear quickly climbed to less than ten floors, but their physical strength was no longer sufficient to immediately engage in fire fighting. Therefore, fire elevators must be installed after a certain level to protect the physical strength of firefighters. The height of ordinary fire ladder trucks is limited, so the maximum number of floors for an ordinary elevator + a staircase is 11. Otherwise, if the building catches fire, the firefighters will not be able to climb up.
Looking at the height of the general ladder truck, which is about 50 meters (Ladder Fire Truck_Baidu Encyclopedia), it is difficult to directly rescue buildings above 18 floors (18*3m=54m). This is also the fire code that requires the 18th floor to be a hurdle. Above the 18th floor, smoke-proof stairwells must be set up to strictly ensure evacuation safety.
If a fire breaks out in the middle of a building over 100 meters tall, it will be difficult for people on top to rescue it (not every city has helicopters). Therefore, the regulations require that public buildings exceeding 100 meters (around 30 floors) must have a refuge floor. Moreover, the height of the first refuge floor shall not be higher than 45 meters to facilitate fire rescue. As for residences exceeding 100 meters, due to their non-public construction properties, they must be handled in accordance with local requirements. (Generally not set).
The above are probably some of the principles for stipulating the number of floors in the fire protection code for high-rise civil buildings. The number of floors converted from these heights is roughly the source of the specific number asked by the questioner.
Answer 3:
When doing architectural design, unless Party A requests it, the designer will do it according to the limits allowed by the regulations. The advantage of this is that Party A's cost can be reduced to the greatest extent while meeting the specifications.
The number of floors in a residential building is often set based on the allowed upper limit of the regulations. This can minimize the building footprint, correspondingly reduce the excavation area of ??the foundation pit/reduce the number of piles; expand the area of ??greening or squares; expand the distance between buildings; optimize sunlight conditions, etc.
Of course, dissatisfaction with the upper limit of the number of floors also happens from time to time. The reason may be that the area was calculated incorrectly before the design. As a result, the designed number of floors was cut off and one floor was not built. There are also cases where Some relatively conventional reasons, such as insufficient sunshine, planning height restrictions, Feng Shui, local regulations, etc.
Article 3.1.2 of the "General Design Principles for Civil Buildings" (GB50352-2005) classifies residential buildings according to the number of floors: the first to third floors are low-rise residential buildings, and the fourth to sixth floors are multi-storey residential buildings. Seven to nine storeys are mid- to high-rise residences, and ten or more floors are high-rise residences. Almost all regulations limiting the various types of residential buildings are based on this classification standard.
For example:
"Residential Building Code" (GB50368-2005)
Article 5.1.5 The net height of balcony railings for residences with six floors or below shall not be It should be lower than 1.05m, and the clear height of balcony railings for residential buildings with seven floors or above should not be lower than 1.10m.
Article 5.3.3 The width of the entrance platform of residential buildings with seven floors or above shall not be less than 2.00m.
There are too many detailed regulations like the above to list them all. However, in terms of construction and installation costs, these are negligible and have no impact at all.
It is really the elevators and stairwells that have a greater impact on construction and installation costs, housing acquisition rates and other indicators related to the interests of all parties:
1. Elevators
"Residential Design Code" (GB50096-2011)
6.4.1: Elevators must be installed under one of the following circumstances:
1 Residential buildings with seven floors or above or When the height of the resident entrance floor from the outdoor design ground exceeds 16m;
6.4.2: For residential buildings with 12 floors or above, there should be no less than two elevators in each building, among which An elevator should be provided to accommodate stretchers.
"Code for Fire Protection Design of High-Rise Civil Buildings" (GB50045-95)
6.3.1: The following high-rise buildings should be equipped with fire elevators:
6.3.1.3 10 Unit-type residences and corridor-type residences with two floors and above.
So, if you don’t want to install an elevator, you can reach the sixth floor, but if you only want to install an elevator, you can reach the eleventh floor. Elevators increase the cost and affect the room availability rate. Generally, no Party A uses the elevator as a selling point.
2. Stairwell
"Code for Fire Protection Design of High-Rise Civil Buildings" (GB50045-95)
6.2.3.1 Eleventh floor and below Unit-type residences do not need to have closed stairwells, but doors opening to the stairwells should be Class B fire doors.
6.2.3.2 Twelve- and eighteen-story unit residences should be equipped with enclosed stairwells.
6.2.3.3 Unit residential buildings with 19 floors or above should be equipped with smoke-proof stairwells.
(The above answers were published on 2015-06-10, please refer to the actual current relevant home purchase policies)
For more real estate information, policy interpretations, expert interpretations, click to view
p>