[Report] A Modular House Built in Two Days... Quality Also Sturdy

GS Construction Modular Housing Brand Jaigaist
Factory-style Production... Unit Cost Reduced by Bulk Purchase, Quality Secured
Concentrated Construction Technology Including Interior and Exterior Materials, 8-layer Structure
6 to 7 Million KRW per 3.3㎡... Construction Cost Remains an Obstacle

"Currently, weekend consultations are fully booked. Due to high demand, we are planning to build a second factory in Asan to increase production capacity."

A 54.9-pyeong modular detached house sample located at the Jaigaist production factory in Dangjin, Chungnam, visited on the 3rd.
[Photo by Kwak Minjae]

On the 3rd, at the 'Jaigaist' production factory in Dangjin, Chungnam, Marketing Team Leader Lee Jun-young said, "Since February, the cumulative number of visitors to the factory has reached 1,000," adding, "We truly feel that the market's interest in modular (prefabricated) single-family homes has recently surged." Jaigaist is a modular single-family home brand recently launched by GS Construction. GS Construction is the first major domestic construction company to enter the modular single-family home market. Modular homes are built by producing the basic framework and walls entirely in the factory and then transporting and assembling them on-site.

At the Dangjin production factory, which spans 33,000㎡ of land, up to 300 wooden modular homes can be produced annually using the prefab method. Prefab is short for 'Pre-fabrication,' a construction method where components are pre-manufactured, transported, and then assembled on-site. Since there is no separate framework construction on-site, the construction period can be reduced by 35-44% compared to traditional methods.

However, the company explains that the prefab method not only shortens construction time but also improves quality. Modular homes are provided in relatively fixed unit forms, allowing for bulk purchasing of materials and interior finishes, which lowers costs and ensures quality. In fact, a single panel (wall) used in Jaigaist wooden homes contains a total of eight interior materials: insulation, structural plywood, drain wrap, PF board, rainscreen, rock board, variable moisture-permeable waterproof membrane, and structural materials. Team Leader Lee explained, "Compared to conventional single-family homes, the addition of exterior insulation like PF board and moisture-permeable waterproof membranes enhances the insulation and moisture permeability performance of wooden homes."

Potential issues during on-site construction can also be minimized. Factory Manager Koo Ja-seok said, "Insulation materials lose their function if they get wet, so preventing moisture exposure is crucial. However, on-site construction can sometimes be exposed to rain and other problems," adding, "With the prefab method, since modules are fully produced in the factory and only assembled on-site, it can prevent quality degradation issues that might occur on-site to some extent."

On the 3rd, a module for testing airtightness was installed at the Jaigaist production factory in Dangjin, Chungnam.
[Photo by Kwak Minjae]

At the factory, construction technologies used in wooden homes were being tested in real-time. The wooden home module wrapped in black moisture-permeable waterproof membrane is a module for testing airtightness by measuring the sealing state against gases. Team Leader Lee said, "No matter how much heating or cooling is done in a single-family home, if cold air enters or escapes, energy efficiency inevitably decreases," adding, "By precisely cutting and producing the structure in the factory and installing the appropriate moisture-permeable waterproof membrane, air gaps can be minimized, thereby improving energy efficiency."

Inside the Jaigaist production factory in Dangjin, Chungnam, visited on the 3rd. Modules are manufactured here through an automated system process.
[Photo by Kwak Minjae]

Inside the Dangjin production factory located opposite, the automated system process for producing modules could be seen at a glance. On both sides of the factory, machinery imported from Germany, a powerhouse in wooden housing, was arranged according to each process. The machines cut wood and nail it precisely according to the input design. Factory Manager Koo said, "A series of tasks including frame production, plywood bonding, cutting, inserting interior materials, panel assembly, electrical installation, and gypsum work are automated, allowing one house (using 8 modules) to be completed every two days."

There are two sample houses here: the main models of 35.9 pyeong (118.7㎡) and 54.9 pyeong (181.5㎡). On the first floor of the 54.9 pyeong house, a spacious living room and courtyard caught the eye. On the second floor, a large terrace stood out. Both house types have a master bedroom with a dressing room and bathroom. Notably, the first-floor ceiling height is designed at 2.59m, higher than typical apartments, enhancing space utilization and openness. Although design changes are limited in modular homes, it is possible to modify room layouts or expand living spaces according to the homeowner's preferences and tastes.

Living room view of the first floor of the Jaigaist modular detached house, 54.9 pyeong.
Photo by Kwak Minjae

However, despite the factory production method, the somewhat high price is a hurdle. Currently, the construction cost of the sample houses offered by Jaigaist, excluding internal materials such as system air conditioners, is 255 million KRW for the 35.9 pyeong (118.7㎡) model and 399 million KRW for the 54.9 pyeong (181.5㎡) model. The construction cost per 3.3㎡ is around 6 to 7 million KRW. Additionally, the modular delivery fee, which does not occur in typical single-family home construction methods involving concrete pouring and rebar placement, adds to the burden.

The real estate industry still views the market outlook for modular single-family homes, which offer excellent convenience and quality, as bright. Team Leader Lee said, "The baby boomer generation approaching retirement has strong desires for health, country homes, and second houses. With the rise of remote work due to COVID-19, changes in perceptions of living spaces, and new concepts like '5-do 2-chon' (living in five big cities and two rural areas) and workations emerging, the demand for high-quality single-family homes is expected to continue increasing."