Why the Sugar House complex that caught fire is still burning

The acrid smell of smoke still filled the air almost two days after a Sugar House development became an inferno late Tuesday and fire crews ultimately decided to demolish part of the structure.

Salt Lake City fire crews were rotating through the area early Thursday to extinguish hot spots from the still-burning fire at what was to be The Residences at Sugar Alley, as well as mitigate smoke and fumes, Capt. Shaun Mumedy said at a news conference.

He said the building could continue to smolder for at least the next 48 hours.

By Thursday, the partially constructed north wing of the U-shaped, eight-story residential and commercial property was mostly destroyed. The south wing was damaged; its roof was still burning Thursday, and many windows were blown out due to an “oven effect” created by the north-wing fire.

The building’s Salt Lake City developers, the Lowe Property Group, intend to “rebuild the property as it was designed,” a California-based spokesperson said in an email early Thursday.

In the meantime, questions remain about how the fire started and spread, and why people nearby may continue to see smoke. There’s also no dollar estimate of how much damage the fire has caused.

Why is the building still burning?

The Residences at Sugar Alley is still smoldering in part because of the way a section of the building collapsed, Mumedy said.

The north wing burned before largely falling in on itself in a way that was “very similar to 9/11,” Mumedy said. “You just have a collapse of a structure, and then there’s just this dense pile of debris, and it just continues to smolder for a long time.”

The roof of the Sugar Alley development’s south wing is still smoldering because of the material used to construct it: thick, plastic foam covered with a thin layer of tar, topped with a rubber membrane.

Such substances are used on apartment-building roofs all over Salt Lake City but melt and burn slowly, Mumedy said.

How did this happen?

The Salt Lake City Fire Department is working with Unified Fire Authority and the Bureau of Alcohol, Tobacco, Firearms and Explosives to determine the cause of the fire, but investigators have not come to any conclusions yet, Mumedy said.

“It’s going to be a long investigation,” he told The Salt Lake Tribune on Thursday.

Does construction create more fire danger?

In general, buildings that are under construction are “absolutely” at greater risk of burning, the captain said. A lot of that is because partially constructed buildings often do not have fire protections in place, such as sprinklers, or the fire hydrant out front is not connected yet.

Inside, construction workers also operate blow torches, welding materials and oftentimes large heaters, and each item carries a risk of fire, he said.

Buildings under construction also have a lot of exposed wood, which can cause a structure to go up in flames “like a tinderbox,” Mumedy said.

Was the Sugar Alley location more dangerous?

The Sugar Alley development — located at 2188 Highland Drive, in the heart of Sugar House’s business district — is situated right next to several other apartment buildings, in a densely populated area.

For fire crews, Mumedy said, areas like that can be especially tricky, because it’s harder for fire trucks to get in and out.

“And then, just the proximity of these other apartments — they’re so close that a lot of that radiant heat poses a threat to them as well,” he said.

The fire remains under investigation as it continues to burn. No injuries had been reported as of Thursday.

Fire officials announced early Thursday evening that residents who were evacuated from the immediate area late Tuesday would remain displaced overnight Thursday amid continued demolition and firefighting efforts.