The investigation into the cause of the fire at the Jacks Point clubhouse and restaurant near Queenstown on August 10 is expected to take up to six weeks.
Fire risk management officer Stu Ide said several items had been sent away for analysis.
"It’s not a simple investigation — there are quite a few factors involved."
The fire had caused "quite extensive damage" to the building’s roof, Mr Ide said.
The restaurant and golf pro shop are closed until further notice.
Restaurant owner Amisfield has not responded to requests for comment.
