by Word count 2000 Reading time 4 minutes No one gives us wisdom, we must find it ourselves.
In prefabricated buildings, we are particularly concerned about two issues – which components should be selected for prefabrication with the lowest incremental cost? Under the prefabrication rate of 15%, 30%, and 40%, which component prefabrication is the most economical to choose? From the perspective of real estate development projects, the author of this article takes the Shanghai project as an example to analyze and summarize this case for peer reference.
1.
Incremental cost analysis for prefabrication of different components: The estimated unit prices of the following data are quoted from a project in Shanghai.
At that time, the supply price of steel bars was 2900 yuan/t.
The composite layer concrete is temporarily calculated based on the comprehensive unit price for full cast-in-situ casting; Due to the unique nature of the project and the particularity of Shanghai’s policies, the following calculations are for reference only, and should be cited with caution.
Taking a project in Shanghai of our company as an example, we conducted a cost calculation and analysis on the replacement of cast-in-situ and prefabricated components for the following four types of main components.
The results are as follows: the incremental cost after replacement: exterior wall panels>balcony panels>stairs>laminated floors.
However, we need to consider that the use of laminated floors will increase the overall concrete volume.
For each 1m3 of laminated floors, the total concrete volume is increased by about 0.2m3 compared to the traditional process, increasing the self weight of the structure.
The actual additional cost per square meter of laminated floor slab is 2400 yuan/m3.
Therefore, when the traditional design of reinforced concrete (or masonry) for the above parts is converted to a fabricated PC design, the incremental cost is analyzed from low to high as follows: the incremental cost of replacing four types of components: stairs (2378), laminated floors (2400), balcony panels (2862), and exterior panels (3157): Component combination schemes with different prefabrication rates are analyzed based on the following three types of business: superimposed villas, western-style houses, and high-rise buildings.
The economic combination schemes for main single components under different prefabrication rates are as follows: 1.
superimposed villas superimposed villas (you can click and zoom in to view).
(1) superimposed villas have a prefabrication rate of 15%, and only external enclosure components (exterior wall panels, balcony panels) can meet the PC rate requirements.
(2) The stairs of the superimposed villa are not standardized, so when the prefabrication rate is 30% or 40%, the superimposed floor component is selected.
(3) The prefabrication rate is 30% → 40%, and the proportion of exterior wall panels increases from 63% to 72%.
2.
Western-style house (1) The prefabrication rate of Western-style house is 15%, and only the outer enclosure components (exterior wall panels, balcony panels)+stairs can meet the PC rate requirements.
(2) The prefabrication rate is 15% → 30%.
As the price of laminated floor slabs is higher than that of exterior wall panels, it is recommended to add laminated floor slabs.
(3) The prefabrication rate is 30% → 40%, and the proportion of exterior wall panels increases from 58% to 68%.
3.
The prefabrication rate of high-rise buildings (1) is 15%, and only the outer enclosure components (exterior wall panels, balcony panels)+stairs can meet the PC rate requirements.
(2) The prefabrication rate is 15% → 30%.
As the price of laminated floor slabs is higher than that of exterior wall panels, it is recommended to add laminated floor slabs.
(3) The prefabrication rate is 30% → 40%, and the proportion of exterior wall panels increases.
However, due to the large space available for balance in high-rise buildings, the proportion of exterior walls does not increase much, increasing from 56% to 58%.
The incremental costs under different formats and different prefabrication rates are calculated using a project in Shanghai as an example to obtain the incremental cost values corresponding to different formats and different prefabrication rate schemes.
Note: Due to the unique nature of the project and the particularity of Shanghai’s policies (the case studied in this article is for the Shanghai region, where exterior wall panels are used.
If exterior wall panels are not used or used sparingly in other regions, the incremental costs will be reduced accordingly), the following calculation data are for reference only, and should be used with caution.
In summary, this article focuses on the comparison and selection of two common schemes in the process of real estate development.
Taking Shanghai as an example, the incremental cost of prefabrication of the same building and different components ranges from low to high: laminated floor slab Due to the limitations of the number of cases and personal level, criticism and correction are welcome. The next chapter mainly introduces the comparison of fabricated structural systems, the other three factors affecting incremental cost, and the exploration and research of fabricated structural processes. Please look forward to it. Recommended reading: Click on the title below and read directly. When cost management encounters prefabricated buildings (1) What is the difference in cost management between prefabricated buildings? Comparison of prefabricated steel structure and traditional concrete structure schemes Assembled cost management dry goods collection (1.0).
.
