In this blog post, we will examine the principles and advantages of the modular assembly method, which dramatically reduces construction time, and look at its potential and limitations through actual application examples.
When walking down the street, it is easy to see buildings under construction. If you pay a little attention to such sites on your daily commute, you can estimate how long it takes to complete a building. Currently, there are new construction sites in front of Building 39 and the gymnasium on the Konkuk University campus. Therefore, if you go to and from class, you can watch the construction of a new building from start to finish. Through this, you can see that it takes about two years to construct a five-story building. Then, how long does it take to construct a 30-story building? Four years? Five years? It is said that it takes about three years to construct a typical 30-story apartment building. However, according to Hanmi Global, a construction management (CM) company, applying the “2-Day Cycle” construction technique, which was successfully implemented last September, can reduce the construction period from the current three years to one year. Reducing three years to one year seems remarkable, but last year, a 30-story building was constructed in China in just half a month.
How on earth did they build a 30-story building in just half a month? The secret lies in the modular assembly method. The modular assembly method involves manufacturing 93% of the building in a factory and then assembling it on site, just like building with Lego blocks, which is why such a huge reduction in construction time was possible. In the case of reinforced concrete structures, which are most commonly used in construction, it is necessary to wait for the concrete to set and harden to achieve the required strength, so it is inevitable that the construction period will be long.
Similar prefabricated buildings are also gaining popularity in South Korea. Called the modular system, it is a construction method in which standardized building modules are manufactured in a factory and assembled on site, as in China, reducing construction time by up to 50%, construction costs by up to 20%, and enabling 70% of buildings to be relocated and reused. This modular system construction can be broadly divided into two types: the unit modular method and the semi-panelizing method.
The unit modular method involves manufacturing the entire house in a factory like a container box, moving it to the site where the foundation has been completed, and then completing the building. Since the entire house can be relocated as is, vertical and horizontal extensions are easy, but the disadvantage is that the house design cannot be changed. The second method, semi-panelizing, involves assembling steel pipes and steel tubes to form the frame of the building, and then attaching metal materials and interior and exterior finishing materials to the frame. This method is similar to that used to construct a 30-story building in China, and has the advantage of being easy to maintain as it can be partially replaced or demolished and recycled. However, since the ceiling, walls, and floors are constructed after the frame is assembled, construction is complicated and special metal joints must be used, so the advantage of shortening the construction period is not as great as with the first method.
Although each construction method has several disadvantages, the biggest advantage is the reduction in construction time, which reduces noise, dust, and vibration damage to the surrounding area during the construction of a building. Considering the profits that can be gained from commercial facilities such as large supermarkets and hotels if they are completed as soon as possible, I think this is the best construction method. In addition, if the assembled parts can be dismantled and reused, it will be possible to achieve two benefits at once, given the current preference for eco-friendly construction due to stricter regulations on construction waste following the introduction of a carbon tax.
