Crews have begun construction on South Korea’s first timber high-rise, a 13-storey apartment tower built in load-bearing cross-laminated timber, as the country opens its rulebook to mid- and high-rise mass timber construction. That is according to Lee Hyuk, who leads the innovation division at Seoul practice Gansam, the architects who opted for cross-laminated timber walls and floors over reinforced concrete.
Developers were long held to four- or five-storey construction, a limit the government cleared when it scrapped the 18-metre cap that once governed the height of wooden buildings. “Those height regulations have since been abolished,” said Yang Pyeong-gang of the Korea Forest Welfare Institute, whose seven-storey Forest Welfare Comprehensive Education Centre has stood as the country’s tallest wooden building since last year.
The fire-certification framework is moving up with the cranes, each new rating carrying wood a tier higher. A two-hour fire test cleared at a Korean lab in February opened certification for mass timber to 12 storeys, with full fire and acoustic testing on track to wrap in 2026–27 and a three-hour rating set to carry wood higher still.
Engineers at the University of Seoul, led by Sungmo Choi, mapped that climb a year ago, setting out the certification requirements for mid- and high-rise wood construction. A one-hour rating was standardised by the national building technology institute, whilst three-hour performance moved into testing — a hybrid of cross-laminated timber and a reinforced concrete core, the surest route to height.
South Korea Is Closing the Gap on Japan and the West
Mass timber was cleared to 18 storeys in the United States and 12 in Canada years ago, each limit tied to graded fire tests that Korea is only now completing. Japan grades its buildings by height, and Port Plus, an 11-storey all-timber tower in Yokohama, was well ahead of South Korea, which set out to close a gap that Singapore and the Nordic nations had opened ahead of it.
Wood Central understands that 18 of the complex’s 130 units are located in two towers of 13 and 11 storeys, built so that the walls and floors carry the load rather than the columns and beams alone. Only the foundation is reinforced concrete, with everything above raised on a seven-layer cross-laminated timber structure milled from Finnish spruce.
The confidence in that timber rests on how it behaves once it catches fire, charring its surface to form a layer that shields the structural wood beneath. “It forms a protective layer even when exposed to fire,” Lee said in comments broadcast by SBS, a process the national lab has clocked at about a millimetre of char a minute on Korean larch panels.
That slow, predictable burn is what lets engineers design around it, sizing timber so a charred margin protects the load-bearing core for the rated hours. Norway’s Mjøstårnet held through a 90-minute test with up to 74 millimetres of its columns turned to char, and Milwaukee’s Ascent came through a three-hour fire with about 100 millimetres gone and more than half its timber left exposed.
Those towers set the modern benchmark for tall wood, and the record has just changed hands. Milwaukee’s Ascent, 25 storeys at 86.6 metres, held the title of world’s tallest hybrid timber building until Sydney’s Atlassian Central overtook it in April, a 39-storey tower reaching 183 metres that is due for completion in November.
South Korea lived in timber Hanok houses for centuries before reinforced concrete took over in the 20th century, and Gansam now returns that material to its apartment towers. For Choi’s team, one milestone remains — a three-hour fire rating for tall timber — the certification Korea’s laboratories are completing as the first 13-storey block goes up.
