The fourth floor of the Major Cineplex Pinklao building has to be torn down because of severe fire damage, according to Suchatvee Suwansawat, president of the Engineering Institute of Thailand (EIT).
He made the recommendation after EIT experts inspected the ravaged building on Saturday. They were joined by officials from the Bangkok Metropolitan Administration Public Works Department, representatives of the complex and police officers.
They found that the two-hour blaze on Thursday did not cause structural damage to the first, second and third floors of the building but the fourth floor could not be saved.
Mr Suchatvee said the structural steel on the fourth floor had buckled and should be torn down before rebuilding could be done.
The building was not in danger of collapsing because its overall structure remained strong, he added.
The EIT believed the fire could have been caused by an electrical short-circuit, but police forensics officers will determine the exact cause after they check evidence collected from the scene.
The engineers said the building had adequate fire-prevention equipment but it could not cope with the blaze, which spread quickly because of the flammable materials inside the building including carpets in the cinemas.
Forensics experts inspected the building on Friday. Pol Col Anurach Jitsil, chief of the forensics team at the Central Police Forensic Science Division, said the preliminary inspection indicated the blaze first erupted in the projection room of cinema No.7 on the fourth floor.