Internationally, prefabricated buildings are regarded as major changes in the construction industry and have been widely used in developed countries. However, in China, its promotion is not smooth-the proportion of new buildings is less than 5%, and it is mostly used in public buildings such as stadiums. Why are prefabricated houses unpopular? There are indeed many technical reasons, but more of them are the constraints of cost. This paper will explain the "puzzle" of the assembly building cost for you.
At the end of September, 2065438+2006, the State Council issued "Guiding Opinions on Vigorously Developing Prefabricated Buildings" (hereinafter referred to as "Guiding Opinions"), proposing that it will take about 10 years to increase the proportion of prefabricated buildings to 30% of new building area from less than 5% at present. From the overall perspective of economic development, the development of prefabricated buildings is also of great significance.
Then, what are the difficulties in promoting prefabricated buildings in China, and how should we solve them?
Confusion:
Technology needs to be improved, and the cost per square meter is about 100 yuan -200 yuan.
Internationally, prefabricated buildings are regarded as major changes in the construction industry and have been widely used in developed countries. However, in China, its promotion is not smooth-the proportion of new buildings is less than 5%, and it is mostly used in public buildings such as stadiums.
Why are prefabricated houses unpopular?
Among them, there are indeed reasons why the technology is not mature enough.
At present, the main structural problems of steel structure residential buildings built in China are not serious, but they also show some shortcomings, such as wall cracking, uneven joints between plates, poor sound insulation effect and poor thermal insulation effect. "Some construction implementation units have insufficient experience, low technical level and inadequate management, resulting in the quality of the project being inferior to that of traditional buildings." For example, Yan Cen, director of Shenzhen Building Science and Technology Promotion Center, said that the unreasonable splitting scheme would cause the civil construction cost to rise by 30%; When hoisting components, each type of work is not well coordinated, and rework is time-consuming, which will cause casualties. ...
However, some insiders are optimistic about this.
"Technical problems can be improved by trial and error." Zhang Huiqing, chairman and party secretary of China 22nd Metallurgical Group, said that since 20 14, they have tackled the technical problems of steel structure residence on the basis of meeting the existing standards. At the beginning of this year, they have overcome the problems of fire prevention, anti-corrosion and sound insulation. "Compared with the level of traditional buildings, the level of prefabricated buildings will only be higher.
Compared with technical defects, cost factors have more obvious constraints on the promotion of prefabricated buildings, which need to be solved urgently.
Generally speaking, in the assembly stage, prefabricated houses can save costs in terms of manpower, construction period and decoration, but the cost of prefabricated components is higher. "Compared with traditional cast-in-place, the unit price per square meter will increase by 100 yuan depending on the prefabrication rate-ranging from 200 yuan." According to Liu Xuan, chief engineer of China 22nd Metallurgical Group, the higher part can be ignored in the construction cost of mega-cities such as Beijing and Shanghai, but it is not small in the construction industry of large and medium-sized cities such as Tangshan.
The disadvantage in cost is largely caused by the small scale of the project. For example, in the production of precast concrete members, the cost of molds accounts for a large part, and the amount of work is small, so the cost of spreading to each member will inevitably rise. "When the scale is relatively small, prefabricated buildings are slightly more expensive than traditional methods." Chen Yiming, chief engineer of the Ministry of Housing and Urban-Rural Development, believes that when the number of projects reaches a certain scale, enterprises have standardized, scientific and orderly management and relatively skilled staff, and the cost can be completely reduced.
Way out:
"Small scale leads to high cost, which in turn limits the scale expansion." Chen Weiguo, chairman of China Construction Technology Wuhan Co., Ltd., said frankly that the government needs to reach out to prevent the mobile home from falling into an "infinite cycle" of development. "If the market demand is activated and there are more projects, the cost problem will be solved, and the advantages will be more obvious, so that assembled houses can embark on a benign track faster. Otherwise, most companies will continue to wait and see. "
As Chen Weiguo said, from a "vicious circle" to a "benign track", external policy forces are essential. In fact, before the the State Council Document was issued, in recent years, many provinces and cities have issued encouragement and support policies aimed at environmental protection, energy saving and promoting the transformation of building methods.
Some are "hard levers". For example, Shanghai proposed that from 20 16, all new civil buildings within the outer ring road will be prefabricated buildings, and more than 50% outside the outer ring road; For another example, in a land transfer in June this year, Nanjing also put forward clear requirements for the proportion of prefabricated buildings and the assembly rate of buildings.
Some of them are "real money". In Beijing, residential industrialization projects that meet the relevant conditions can be rewarded with a planned construction area of no more than 3%. In Shanghai, within a certain policy period, for prefabricated residential projects with a total construction area of over 30,000 square meters, if the prefabricated assembly rate reaches 40% or above, a subsidy of RMB 100 per square meter can be obtained, and the maximum subsidy for a single project is RMB1000.
"The measures in the guidance have a clear direction and look forward to the early implementation of local policies!" Zhang Huiqing believes that with the increase of support, prefabricated buildings will develop by leaps and bounds as early as next year.
There are many similar "troubles"
A few years ago, some steel structure enterprises deviated from the current building standards when making prefabricated houses, which led to the failure of acceptance after completion. In addition, because capable enterprises are a minority in the industry, they are often in a weak position in the right to speak. Some enterprises report that "enterprises that can't do assembly will naturally try their best to convince developers,' why bother to give up assembly!' "Some companies say that if the prefabricated houses can be finely decorated, such as uniformly installing wallpaper, bay windows, cabinets and so on. They can completely "smooth" the higher cost of structural parts, but as "intruders" in the construction industry, it is even more difficult to get a share in the decoration industry.
So, what is the cost of prefabricated buildings? How to calculate the project cost?
In order to implement the requirements of the Guiding Opinions of the General Office of the State Council on Vigorously Developing Prefabricated Buildings on the basis of pricing, the Ministry of Housing and Urban-Rural Development recently organized Zhejiang Housing and Construction Department and other units to compile the Consumption Quota of Prefabricated Buildings (draft for comments). It includes four chapters: assembled concrete structure engineering, assembled steel structure engineering, building components engineering and measures.
This quota is compiled according to the current Code for Construction Acceptance of Assembled Building Engineering, quality evaluation standards and safety operation procedures, in accordance with normal construction conditions and reasonable labor organization and construction period, combined with the construction methods and mechanization degree adopted by most domestic construction enterprises at this stage.
This quota is the consumption standard of labor, materials and construction machinery required to complete the partial items and measures of the specified measurement units, and it is the basis for the construction project quota to be determined by the engineering cost management institutions of all regions and departments, and also the basis for the investment estimation, design budget estimation and the highest bid price limit (pre-tender estimate) of state-owned projects.
The most concerned thing in the exposure draft is that the investment estimates of eight kinds of prefabricated concrete houses and prefabricated steel structure housing with different PC rates are given respectively, which makes the "cost account" of prefabricated buildings have a clear and unified standard and basis.
note:
Before giving specific reference indicators, it is necessary to popularize two concepts-
Assembly rate: (also known as PC rate) the ratio of the volume of precast concrete used within the scope of building monomer to the total volume of concrete. Usually, the accounting is based on the part above plus or MINUS zero, and the state has no unified and clear regulations for the time being. The assembly rate index reflects the degree of industrialization of buildings. The higher the assembly rate, the higher the degree of industrialization.
Assembly rate: the proportion of single building area meeting the requirements of assembly rate to the total building area of the project.
Precast concrete residence
1.PC rate is 20% (above 0.00), and the assembled concrete small high-rise residence.
2. Assembled concrete small high-rise residence, with PC rate of 40% (above 0.00).
3. Assembled concrete small high-rise residence, with PC rate of 50% (above 0.00).
4. Assembled concrete small high-rise residence, with PC rate of 60% (above 0.00).
5. Assembled concrete high-rise residence, with PC rate of 20% (above 0.00).
6. Assembled concrete high-rise residence, with PC rate of 40% (above 0.00).
7. Assembled concrete high-rise residence, with PC rate of 50% (above 0.00).
8. Assembled concrete high-rise residence, with PC rate of 60% (above 0.00).
9. Assembled steel structure high-rise residence (above 0.00)
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