Heavy rain had overloaded and collapsed the guttering of a new passenger hall at Don Mueang airport on Monday evening, bringing down part of the roof and wall, according to Airports of Thailand.
AOT president Nitinai Sirismatthakarn said an initial investigation found the amount of rain dumped by the downpour greatly exceeded the capacity of the gutters of the Service Hall, and they collapsed.
He said there was no damage to the main structure of the Service Hall.
Transport Minister Saksayam Chidchob said he had set up a fact-finding committee to investigate the incident, headed by transport deputy permanent secretary Pisak Jitwiriyawasin.
The committee would provide a damage estimate within two weeks and conclude its inquiry in a month, the minister said.
The Service Hall is for tour groups. It was completed near Terminal 1 of Don Mueang airport in 2020, but it had not been used because the number of passengers through the airport remained low due to Covid-19.