How Many Floors Can Prefabricated Houses Be Built?
There is no unified national standard for the number of floors that prefabricated houses can be built, which specifically depends on local policy regulations and the type of house. The common situations are as follows:
1. Ordinary non-modular panel houses
The floor limit of ordinary non-modular panel houses is related to earthquake risk. In non-earthquake areas, their design load-bearing capacity allows for construction up to 6 floors. The structure of such houses is mainly composed of traditional prefabricated components spliced together, with relatively stable connection strength. However, when exceeding 6 floors, additional structural stability reinforcement is required, such as adding shear walls or reinforcing the foundation. In earthquake-prone areas, the number of floors needs to be further reduced according to local seismic codes, usually not exceeding 4 floors to ensure structural safety.
2. Modular prefabricated houses
Modular houses are built by assembling factory-prefabricated units on site. The strength of their connection nodes (such as bolts and welds) is weaker than that of monolithic cast-in-place structures. Therefore, it is recommended that the number of floors not exceed 5. Even with optimized connection technologies (such as high-strength bolts or grout connections), strict adherence to design codes is still necessary to avoid connection failures under horizontal loads (such as wind and earthquake forces) due to excessive floors. In some cases, modular houses can achieve 6-floor construction by adding lateral force-resisting systems (such as steel frame supports), but this requires special论证 (demonstration/approval).
3. Prefabricated buildings in big cities
In first-tier cities like Beijing, policies allow for a significant increase in the height of prefabricated floors. For example, Beijing allows prefabricated structural buildings to reach up to 14 floors, but in actual construction, it is generally controlled within 12 floors. This difference stems from the contractor's consideration of safety margins—reducing the number of floors can decrease the risk of structural deformation and facilitate the configuration of fire protection, elevators, and other equipment. In addition, high-rise prefabricated buildings require more complex node designs (such as sleeve grout connections) and construction techniques (such as BIM technology-assisted installation), with costs increasing exponentially with the number of floors.
4. Rural self-built prefabricated houses
When using prefabricated panels to build houses in rural areas, steel reinforcement ring beams must be added for buildings exceeding 3 floors. Ring beams can enhance the overall integrity of the house and prevent wall cracking caused by uneven foundation settlement or horizontal loads. If ring beams are not installed, the seismic performance of buildings over 3 floors will be significantly reduced and may even fail to meet basic safety requirements. Some areas also require the addition of constructional columns to form a "ring beam-constructional column" system, further improving structural stability.
