Las Vegas ? The burned exterior facade along the roof of the Monte Carlo hotel-casino will have to be removed or secured before the Las Vegas Strip resort can reopen, the chief county building inspector said Saturday.

Ron Lynn, chief of the Clark County Building Department, said the 32-story building will remain closed until resort owner MGM Mirage Inc. completes work to the roof-line foam building material damaged in Friday’s blaze.

A spokesman for the casino company said he could not immediately say how long that would take. “Now that the county inspectors have completed their work, we’ll begin our assessment,” MGM Mirage spokesman Gordon Absher said.

Lynn and an assistant, Clark County fire chief Sandra Baker, said most fire damage was to the exterior of the top five floors of the 3,213-room hotel. The roof was not damaged, they said, declining to estimate repair costs.

“The building is in a safe condition,” Lynn said. “We feel it’s habitable from the casino up through the 26th floor.”

The cause of the three-alarm blaze remained under investigation, Baker said.

Officials said Friday that welders were on the roof, where Lynn said the hotel had a permit to install window washing gear. Baker said she did not know what role, if any, workers may have played in starting the blaze.

Seventeen people were taken to hospitals with what ambulance company officials described as minor injuries, mostly from inhaling smoke or fleeing the building.