Over 80% of the Entire Process Manufactured in Factory
Just Transport and Assemble... 30 Minutes per Installation
30% Shorter Duration Compared to Concrete Method
Low Production Volume and High Cost Still Make It Expensive
On the 4th, modular houses are being installed at the LH public rental housing construction site in Sanwool-dong, Sejong City. (Photo by LH)
On the 4th, at the Korea Land and Housing Corporation (hereafter LH) public rental housing construction site in Sanwool-dong, Sejong City, a 600-ton super-large crane was lifting modular units made of concrete and steel. Each modular unit, measuring 3.3m in width, 11.3m in length, and weighing 25 tons, corresponds to a single-person housing unit with a net floor area of 21㎡. Inside this modular unit are the resident's room, bathroom, and kitchen.
After the crane places the modular unit on the 4th floor, on-site workers begin their tasks. Using steel pins, they start the horizontal and vertical assembly between the newly lifted modular unit and the previously stacked ones. This rental housing complex, consisting of a total of 416 units, is being constructed one unit at a time in this manner. The modular units are manufactured at a factory in Gunsan, Jeollabuk-do. Once transported by trailer to the Sejong construction site, the stacking work begins immediately.
It takes about 30 minutes to install one modular unit. At the site, 10 to 12 modular units are placed daily into their designated floors and unit numbers. Larger types, over 30㎡, are made by combining two modular units. This public rental housing will rise up to seven floors and is scheduled for completion in December. Move-in will begin in March next year.
Reducing Construction Period and Workforce... Construction Costs Still Higher
On this day, LH held a 'Modular Housing Site Inspection Press Conference' and announced plans to promote 'Off-Site Construction (OSC)'. The modular construction method involves manufacturing individual residential spaces, including exterior walls, windows, and plumbing, in box form at a factory, then transporting and installing them on-site. Over 80% of the entire process takes place in the factory.
No Tae-geuk, head of LH's Smart Housing Business Team, explained, "Compared to traditional reinforced concrete construction methods, modular housing can reduce construction time by 30%. Since the residential spaces are pre-fabricated in the factory, construction is not hindered by a shortage of skilled workers, and housing quality can be consistently maintained."
However, since the modular market has not yet fully grown, the low production volume results in high costs, making construction expenses expensive. It is about 30% more costly than reinforced concrete methods. Achieving economies of scale can reduce costs, but this requires establishing a mass production base. So far, LH has completed low-rise modular housing totaling 221 units across four districts and is currently constructing modular housing with 696 units in three districts. Plans are underway to build 831 units in two more districts.
The planned districts include the 5-1 living zone of the Smart City pilot city in Hapgang-dong, Sejong City. LH has commissioned a 12-story modular housing complex with 450 units there. In the Chopyeong district of Uiwang, Gyeonggi-do, a 20-story modular housing project with 381 units is being promoted. Construction is scheduled to start between August and September once the contractor is selected.
No said, "The tallest modular housing in Korea currently stands at 13 stories, and the height of modular housing is an indicator of technological capability. Modular housing uses a column (frame) structure rather than a wall structure, so noise does not transmit through walls, resulting in stable inter-floor noise levels below 49 decibels (dB). Its seismic performance is comparable to that of conventional concrete buildings."
Need for Relaxed Building Standards and Simplified Permitting
On the 4th, modular houses are being installed at the LH public rental housing construction site in Sanwool-dong, Sejong City. (Photo by LH)
Already, a 44-story modular housing building has been constructed in the UK, and the US market has grown to support buildings over 30 stories. In Korea, the domestic modular construction market reached 805.5 billion KRW last year, a 396% increase compared to 162.5 billion KRW in 2022. However, most of this growth comes from green smart future schools built using modular methods by demolishing old schools, rather than housing. No emphasized, "To grow the modular housing market, it is necessary to relax modular construction standards and simplify permitting procedures."
Besides modular housing, LH is also piloting precast concrete (PC) construction, another off-site construction method. While modular construction involves manufacturing entire housing units in factories, PC construction produces major components such as columns, beams, and walls in factories and assembles them on-site. Currently, this is being demonstrated as a national R&D project in the Godeok district of Pyeongtaek. A 12-story building with 82 units is being constructed, and the assembly of major components has been completed.
At the press meeting, LH President Lee Han-jun said, "It is becoming increasingly difficult to find workers at construction sites, so the need for modular housing, which can be manufactured in factories and simply assembled, will grow. If LH builds a certain volume focused on public housing starting this year and gradually expands, the market will grow."
© The Asia Business Daily(www.asiae.co.kr). All rights reserved.
