The “mechanical mindset” of Hong Kong building authorities has come under scrutiny at a hearing into the city’s deadliest fire in decades, with a former inspection director conceding his team had “blindly” followed outdated guidelines when deciding not to conduct on-site audits of renovation works at the housing estate ravaged in the blaze.

Rudolf Lau Fu-kwok, who was the head of the Housing Bureau’s Independent Checking Unit when the fire broke out at Wang Fuk Court last November, said on Friday that the old supervision mechanism relied solely on engineering firms to regulate themselves and residents reporting any alleged malpractice to authorities.

He acknowledged that the process had created a “blind spot” in government supervision in cases where residents were unaware of the dangers posed by a particular practice, such as the lack of complaints arising from illegal alterations to the estate’s emergency staircases during a HK$336 million (US$42.9 million) renovation project.

But Lau denied the allegation that the unit did not properly discharge its duties when overseeing construction works at subsidised housing estates, saying it had focused resources on monitoring high-risk procedures during major construction works but had overlooked other minor projects.

“The unit exercises its powers as delegated by the Buildings Department … It has always strived to exercise supervision in accordance with the department’s standards,” he said.

The fire at Wang Fuk Court started on November 26 last year as the site was undergoing repairs required under the mandatory building inspection scheme, spreading to seven of the estate’s eight blocks and raging for around 43 hours.