Prefabricated buildings: a few steps to promote the big "Lego"

At the construction site of Heyuan Community, Sun Street, Hanting District, Weifang City, the steps of the 18-level building weighing 4.7 tons were slowly picked up by the tower crane from the truck and moved to the shelter on the seventh floor. Workers hold crowbars or push or pull flat to ensure that the reserved holes on the steps match the four protruding steel bars at the front and rear. It only took 8 minutes from grabbing to the card slot, and then it was fixed with grouting.

Building a building is like building Lego with building blocks. In recent years, green buildings represented by prefabricated buildings have increasingly entered people's lives. Recently, the reporter interviewed in Weifang, the first demonstration city of prefabricated buildings in the country, to find out what the prefabricated buildings are.

"Lego" style building

At 10 a.m. on June 20, in the prefabricated production workshop of the first phase of Weifang Sanjian Intelligent Assembly Base, Wang Yuhao, a young man born in the 90s, was guarding the automatic spot welding machine for steel bars, counting the circles of welding spots and sparks. Not far away, the rail crane hoisted the built-in steel reinforcement of the bound staircase to the steel form, waiting for the concrete to be poured.

"After pouring and forming, it will be hoisted to the yard for maintenance, and automatically sprayed at regular intervals. The stairs can only leave the factory when they reach the qualified strength." Production manager Guo Xiangyang told reporters.

Compared with the traditional on-site operations at construction sites, factory-produced stairs have realized standardized design, modular production, and assembly construction. Workers can work in a relatively constant temperature workshop, avoiding the intrusion of dust and severe cold and heat.

"The 'Lego'-style construction efficiency is more than double that of on-site pouring operations. We have a total of 15 high-rise projects. Previously, the construction site of the same scale required more than 300 people. Now through the use of more prefabricated components, it has been reduced to 130 people. ” said Zhang Chengkun, project manager of Heyuan Community.

The Yuejiangfu Community in Fangzi District, Weifang City was one of the observation points of the city's prefabricated construction work site promotion meeting organized by the Weifang Municipal Bureau of Housing and Urban-Rural Development last year. The person in charge of the project pointed to the construction site introduction in the green net. The prefabricated parts reduced the workload of on-site concrete and reduced the dust on the construction site. "There is a lot less waste on the construction site, the laminate and wall panels are more flat, and there is no need to level them during decoration."

Prefabricated buildings include both prefabrication of large-scale main components and prefabricated interiors. Entering the office of Zhao Zhongli, general manager of Weifang Youliya Decorative Soft Packing Products Co., Ltd., the recent construction projects are recorded on the whiteboard behind the door: 16 projects such as Weihai Outlet Town, Maohua Aegean Sea, Weifang Shenzhen Science and Technology Park, etc. .

Zhao Zhongli invented an adjustable hanging structure, which can riveted and assemble prefabricated slate, wood and other materials on the wall, eliminating the need for sand and cement smearing on the decoration site, which is more environmentally friendly. "Now projects with tens of thousands of square meters are small, and many projects start with hundreds of thousands of square meters." Zhao Zhongli said that thanks to the prefabricated buildings vigorously promoted by governments at all levels, his performance will double this year.

"I'm going to Weihai Outlet Town to guide the newly recruited installation team. In this 'fool-style' installation method, the components are transported to the construction site and mounted directly. Newly recruited workers are not yet familiar with the technological process, and teaching them skills can help them build faster and better. " Zhao Zhongli said.

Insufficient installation team restricts promotion

"Prefabricated buildings have the characteristics of low carbon and environmental protection, but the cost of construction is an important factor for developers to worry about. About one square meter of prefabricated buildings will increase by 200-300 yuan." Lu Zhenyu, head of the Construction Industrialization Section of the Weifang Real Estate Development Service Center, said.

A number of project leaders told reporters that in first-tier cities where house prices can easily cost tens of thousands of yuan per square meter, it doesn't feel much to increase the cost of several hundred yuan, but in third- and fourth-tier cities, consumers are very concerned. Lu Zhenyu said that now Weifang is in the early stage of promotion. If the scale of prefabricated buildings in the city increases, the cost of prefabricated components will drop.

"Like our company, from design, factory processing to on-site construction, and then hydropower installation, decoration, post-operation and maintenance, it has formed a closed-loop whole industry chain prefabricated building development model, so that costs can be well controlled." Li Fei, deputy general manager of Changda Construction Technology Co., Ltd.

The weight of each component is measured in tons. Can construction workers who are used to traditional operations adapt?

In Weifang, the lack of installation workers is a constraint on the promotion of prefabricated buildings. "Weifang has a relatively small team of professional and stable installation workers. Our prefabricated component manufacturers often instruct workers on how to install them." Guo Xiangyang said.

In order to improve assembly efficiency, Weifang Sanjian Intelligent Assembly Base also dedicated half a workshop to train installation workers, so that they can familiarize themselves with the installation process of prefabricated components such as laminated boards as soon as possible.

The Weifang Changda Construction Group, where Changda Construction Technology Co., Ltd. is located, uses the "old to bring the new" to increase skilled workers. "Talents are the most important in any industry. There must be a training platform to form a better talent echelon, so that the project can develop better." Li Fei said.

Guo Xiangyang introduced that due to the lack of corresponding supporting enterprises in third- and fourth-tier cities, the installation efficiency is low. The Weifang market uses wooden molds to form shapes, and some large enterprises with the prefix "中" use recyclable aluminum molds during construction, which can not only reduce costs but also speed up construction, attracting some local enterprises to imitate.

Policies promote the implementation of assembly rate

From a height, the arc-shaped ceilings of the workshops of Weifang Sanjian Intelligent Assembly Base are like waves. Due to the production of low-carbon and environmentally friendly prefabricated building components, it was listed as a priority project for the conversion of new and old kinetic energy in Shandong Province in 2021, and a production workshop of more than 70,000 square meters was built that year.

In November 2019, the Weifang Municipal Government issued a notice on the implementation plan for vigorously developing prefabricated buildings, proposing the overall requirements, specific goals, support policies, and safeguard measures for the development of prefabricated buildings.

"Not only have clear assembly rate requirements, but also formulated 10 support measures in terms of construction land, high-tech enterprise taxes and fees, loan interest discounts, credit rating evaluation, migrant workers' salary deposit, performance deposit, floor area rate incentives, and advance pre-sale." Lu Zhenyu told reporters.

For developers, the speed of payment is crucial. Prefabricated buildings can be pre-sold on the ground floor, which developers attach great importance to. "Weifang also requires that the proportion of prefabricated buildings should be informed in advance and written into the land transfer contract before the auction of new land plots. The pre-sale time in advance is the most critical point to ensure the assembly rate." Lu Zhenyu said.

In May of this year, Shandong Province issued a notice to promote the green transformation of construction methods, and proposed that by 2025, the proportion of newly constructed prefabricated buildings will account for more than 40% of new buildings, and the discharge of construction waste on construction sites should not be higher than 300 tons/10,000 square meters.

Shandong Huayuan Construction Group conducted explorations as early as the 1990s, when they took the lead in adopting large-slab technology in building construction. However, under the technical conditions at the time, problems such as water seepage and cracks at the splices of the wall and floor were not easy to solve. In addition, the construction of heavy components was inconvenient, and the promotion of large-slab technology was once stagnant. Now taking advantage of the policy, the group has relaunched prefabricated buildings.