A crane truck places a modular unit atop UR-2, a residential complex in Sejong, Thursday. A truck delivered the unit from POSCO Architects & Consultants' factory in Gunsan, North Jeolla Province, where it had been assembled. Courtesy of Korea Land & Housing Corp.

Korea Land & Housing Corp. (LH) CEO Lee Han-joon / Courtesy of LH

SEJONG — Korea Land & Housing Corp. (LH) is bolstering construction practices using modular units to lower the risk of defects, and shorten construction periods for apartments and other buildings, according to the head of the state-run agency, Thursday.

Modular construction, an off-site construction (OSC) method, puts together modular units prefabricated by manufacturers in advance and brought to construction sites. Compared to traditional methods in which construction takes place entirely on-site, the new method can save time and allow uniform quality in the end.

LH CEO Lee Han-joon said that although modular construction still requires further research for application to structures of greater heights and larger scales, it is the agency's duty to lead the country's future construction industry by expanding smart construction technologies.

"We're still short of experience and research to apply the modular technologies to a broader part of the construction market here. Demand for the technologies yet remains low and costs for use of the technologies are 30 percent more expensive than the conventional methods," Lee said during a press conference in Sejong.

"But we're currently witnessing clear threats to the industry such as a serious worker shortage and an increasing number of incompetent workers such as foreigners. These particular problems will only get bigger. To resolve the issues, modular construction is inevitable. Once the practice becomes more popular and expands further throughout construction firms, costs for employing the method will naturally go down due to economies of scale."

A showroom of a modular unit for UR-1 and UR-2 in Sejong is outfitted with furniture, lighting, heating, air conditioning and pipes. Courtesy of LH

One of LH's pending goals is to provide the public with enough new residential buildings to replace older ones. Lee said that the agency aims to launch construction of 50,000 new housing units this year and over 60,000 units the following year. Lee's remark hinted that more and more of the units will be built with modular technologies.

"To tackle the shortcomings of the current construction market, its production environment should shift from on-site to factory manufacturing," Lee said. "We're currently building the country's tallest modular structure in Uiwang, Gyeonggi Province, which goes up to the 20th floor and houses over 380 units. Once it's completed, it'll demonstrate the potential of OSC technology."

One of LH's ongoing modular construction projects is in Sejong with less than six months remaining until completion. Two blocks, UR-1 and UR-2, consist of four basement floors and seven aboveground levels. While a conventional construction method using reinforced concrete (RC) was used to build underground parking lots and commercial units on the first two ground levels, 416 residential units in the rest of the structures are built by modular technologies.

Kyeryong Construction, a private builder, was stacking up the modules one after another like toy blocks. The modules were manufactured at POSCO Architects & Consultants' factory in Gunsan, North Jeolla Province. They traveled 140 kilometers by road to the site, complete with pipe systems, some furniture, heating, air conditioning and even wallpaper.

A crane lifts each module attached under a balance beam and places it in a row of other modular units already in place. Each module takes about 30 minutes for complete assembly. LH planned on putting 10 modules in place this day.

"We try to minimize workloads on site by doing the most we can in factories," Kim Soo-jin, an official from LH's Sejong special project division, said inside one of the completed modules on the ground. "We can customize each module by installing different types of air conditioners, furniture and home appliances."

Another LH official said at the site that giving orders to workers is easier inside factories than on site. She said that factory assembly allows "easier communication between workers and regimental quality assurance."

LH eyes the U.K. and Singapore where modular construction technologies are more advanced than Korea. The tallest modular structure outside Korea has already reached the 55th floor.

"For us to reach that figure requires more research to make our units fire-resistant strong enough to endure more than three hours. At the same time, the job must be financially affordable," said Choi Tae-young, another official from the Sejong special project division. "By 2030, we plan to reduce construction periods by 50 percent using modular technologies and also lower the modular construction project costs to the level of conventional methods using RC."