The Public Safety Ministry said Monday that it would tighten safety regulations amid escalating concerns over lax construction rules that let to the deadly apartment fire north of Seoul over the weekend.

On Saturday, the blaze, which started on the first floor of an apartment building, quickly spread to two adjacent residential buildings, killing four and wounding 126 people in Uijeongbu, Gyeonggi Province. Eleven residents were seriously injured, officials said. While a probe is underway into the exact cause, investigative authorities are reportedly downplaying the possibility of an arson at the present stage.

“The ministry will push to require all outer walls of buildings to be built with incombustible materials,” the Ministry of Public Safety and Security said. 

Currently, only skyscrapers, public-purpose buildings and factories are required to construct outer walls with incombustible materials.

Critics suspected that the inflammable outer walls of the apartments caused the deadly fire to spread.

Built by a method called Drivit the inner concrete walls of the Uijeongbu buildings were covered with expanded polystyrene. While this maximizes thermal insulation and reduces construction costs, it is inflammable and releases toxic gases when it catches fire, experts said.

The ministry also vowed to come up with new safety regulations to prevent fires from spreading to adjacent buildings.

The distance between the apartment buildings was only about 1 meter, allowing the fire to spread easily, authorities said.

While local regular apartments must be over 6 meters apart, this rule has not been applied to small urban residential apartments of under 85 square meters since 2009. This was part of the deregulation package released by the former administration to boost apartment construction to resolve the housing crisis.

The public safety officials, meanwhile, said they would soon draft a set of measures to support some 200 apartment refugees who are staying at a temporary shelter.

By Lee Hyun-jeong (rene@heraldcorp.com)