Prefabricated Apartment Eliminates Thudding Noise... 22-Story Modular Achieves Top Grade for Inter-Floor Soundproofing [Real Estate A to Z]

Upon Completion, Will Be the Tallest Modular Apartment in Korea: 381 Units in Uiwang Chopyeong
Airtightness and Seismic Performance Verified, Rated "Excellent" for Long-Life Housing
Public Modular Orders to Expand to 20,000 Units by 2030

The tallest modular apartment building in Korea, constructed by manufacturing concrete frames in a factory and assembling them on-site, will be introduced next year in Uiwang, Gyeonggi Province. Notably, this complex received the highest first-grade rating in both light and heavy floor impact noise tests. The government plans to expand the modular construction method—which can reduce construction periods—to a scale of 20,000 units by 2030, and will support part of the higher costs associated with modular construction compared to conventional methods using public funds.

Mobile PC modular appearance. NRB

According to modular construction specialist NRB on the 24th, they evaluated the floor impact sound insulation performance of the Rahmen-type precast concrete (PC) modular show house to be used in the Korea Land & Housing Corporation (LH) Uiwang Chopyeong A-4BL project. This test involves applying impact to the floor of the upper unit using standardized equipment and then measuring the noise transmitted to the unit below.

First grade is the highest rating out of four levels. Under the current standards, both light and heavy impact noise levels must be 37 decibels (dB) or less to receive this grade. Light impact noises refer to lightweight, sharp sounds such as objects dropping on the floor; heavy impact noises refer to the deep, thudding sounds transmitted when, for example, a child jumps. The Uiwang Chopyeong show house also earned a first-grade rating for its soundproofing performance in walls between units.

This complex is an integrated public rental housing development pursued by LH, with a planned height of up to 22 stories and 381 units. NRB is responsible for its design, manufacturing, and construction. According to the Ministry of Land, Infrastructure and Transport's plan, the project is scheduled for completion in November next year, and once finished, it will become Korea's tallest modular multifamily housing.

The Rahmen structure, where columns and beams support the building’s weight, allows interior walls to be moved or removed easily since they do not bear loads. Most apartments in Korea use a wall-bearing structure. NRB explained, "Heavy concrete floor slabs are advantageous for suppressing the transmission of vibration," and added, "Factory production ensures a flat floor, allowing consistent installation of shock absorbers and finishing layers above it."

The required seismic performance for high-rise apartments has also been verified. NRB integrates the columns as single units and reinforces the joints using grouting with special materials to secure the frame. The building has been designed so that, in the event of an earthquake, the impact is distributed evenly throughout the entire frame rather than concentrated in one place. This framework and the special core walls have been certified by the Architectural Standards Center of the Architectural Institute of Korea. Precast concrete walls used for the stairwells and elevator shafts have also obtained the same certification.

The company also explained that the grouting process, which fills gaps at connections, helps reduce possible air leakage paths. According to the Korea Passive House Association, which tested a 46-square-meter show house in Uiwang Chopyeong following international standard ISO 9972, the airtightness performance indicator, ACH50, was measured at 2.26 air changes per hour. This metric measures the amount of air leakage by creating a set pressure difference between the inside and outside. The lower the value, the less air leakage occurs. NRB noted that this is lower than the pre-existing research average of 2.8 air changes per hour for newly built multifamily housing in Korea.

The building has also been recognized for its durability. This year, it attained an "Excellent" rating, indicating a durability performance of over 65 years, in the Long-Life Housing Certification—the first time for a modular multifamily housing project in Korea. The Rahmen method, where columns and beams bear the load, allows interior walls to be changed relatively freely, resulting in high marks for space flexibility evaluations.

Gyeonggi Uiwang Chopyeong A-4BL - Bird's-eye View. Korea Land and Housing Corporation

The government's purpose in expanding modular public housing is to advance the timing of housing supply. By manufacturing the frame in a factory, the process of setting up formwork and pouring and curing concrete on-site can be shortened. Last April, LH explained that the Uiwang Chopyeong project could reduce the construction period by 114 days compared to the conventional reinforced concrete method.

On August 13, the Ministry of Land, Infrastructure and Transport increased its modular public housing order goal for 2027 to 2030 from 12,000 to 20,000 units as part of its "Swift Housing Supply Plan." Following Uiwang Chopyeong, Gyeonggi Housing and Urban Development Corporation (GH) will conduct a pilot project in Hanam Gyosan A-1 Block featuring a 25-story, 400-unit modular building. Construction will begin in Hanam Gyosan in February next year, with NRB as the contractor. Of 723 units in the complex, 400 will be built as modular units up to 25 stories high. This site is designated as a testbed for high-rise PC modular technology, receiving KRW 20 billion in R&D support from the Ministry. NRB is currently operating the largest single modular factory in Korea, capable of uniformly producing 5,600 modules per year.

One remaining issue before expanding supply is to reduce the construction cost burden. The Land Ministry estimates that modular construction costs about 30% more than conventional on-site construction. According to the "August 13 Measures," the additional cost per unit is about KRW 70 million. The government plans to subsidize about half of this extra cost by 2030.

Quality management standards for each manufacturing and installation stage will be established in line with the increased supply. The Ministry of Land is planning to introduce factory and building certifications by enacting the "Special Act on Supporting Modular Architecture Promotion." Manufacturers will be evaluated on their design, production, and quality management capabilities, as well as on plans for module transport and lifting. Separate supervision and quality control standards tailored for modular construction will also be prepared.

An NRB representative stated, "The Uiwang Chopyeong 4-1BL modular multifamily housing proved not only its shortened construction period, but also its airtightness, soundproofing, seismic resistance, and longevity," adding, "Modular multifamily housing is rapidly evolving from speed to quality."

This content was produced with the assistance of AI translation services.