The nearly two-year long renovation and expansion of the Gaillard Center is expected to be finished in time for the next Spoleto Festival in May, but construction is now going on seven days a week and 16 hours on weekdays.

Nearby neighbors say they were told the work largely would be completed by January, and they were looking forward to relief from the dust, noise and construction traffic that has been disrupting their lives since the city broke ground on the premier concert hall in August 2012.

"It's a big project and a complicated project," Charleston Mayor Joe Riley said of the $142 million center, which will replace the old, cavernous, Gaillard Municipal Auditorium that sat on the site on Calhoun Street since 1968.

The rebuilt 270,000-square-foot building includes a world-class performance hall, as well as space for exhibitions and banquets, and some city offices.

Riley said the building is expected to be finished by April, and must be ready for next year's Spoleto Festival USA, which takes place at the end of May.

On a tour of the building and construction site Friday, Riley climbed to the top of the scaffolding in the concert hall to a construction platform just below the ceiling, which has been named "the dance floor." He pointed to the intricate plaster work taking shape. The double layer of plaster will provide great acoustics, he said. And the detailed design requires gifted artisans. It's the kind of work that simply takes time and attention to detail, he said.

Dustin Clemens, the city's director of capital projects, said city leaders knew from the start that the construction company, Skanska Trident, would at times have to work on weekends and include a second shift. "The details of this building are extraordinary," he said, "They always knew it would take some extra work."

Now, more than 400 employees work weekdays on the site during the day. About 25 are at the site on the second shift. About 100 work on Saturdays and about 10 on Sundays.

Most of the work done in the evenings and on Sundays is indoors, he said, so it has less impact on the neighborhood.

The ramped up schedule likely will be in place through September, he said.

The additional work hasn't added to the building's price tag, Riley said. Money for extra work comes from the project's contingency budget.

And money for changes, also called "change orders," also comes from that budget, he said.

City Council earlier this month approved about $500,000 in changes to the project.

Clemens said the project's contingency budget is about $5 million, and, so far, the city has spent about half of it. The project is more than half complete, he said, so he thinks the contingency budget will be enough to complete the center.

The portion of the building dedicated to city offices will wrap around the back of the building on George Street, he said. Some of the offices destined for the three-story portion of the building likely will move in in January, while construction continues on the rest of the building, he said. The rest of those offices likely will move in between February and April.

Riley said many city offices now are scattered in different locations, and the city pays rent on that space. When the offices move to the new building, money that previously went toward rent will be used to help pay off project bonds.

A residential neighborhood

Angela Drake, president of the Historic Ansonborough Neighborhood Association, said the Gaillard Center is a major construction project surrounded by a residential neighborhood. And despite efforts by the city and Skanska Trident, the last two years have tough for residents who live nearby.

Liz Aktar, whose backyard is directly across from the construction site, said city and Skanska Trident leaders regularly meet with neighborhood residents, and at one of those meetings, they said the work largely would be completed in January. She's disappointed that the completion now is April.

The construction dust alone has changed the lives of her family members, she said. Her home has an outdoor living space that she hasn't used in nearly two years because of the dust. Her outdoor chairs are ruined, and dust is caked into her brick driveway. "We haven't sat outside since this started," she said.

Neighbors demanded an air-quality test several months ago, she said. Clemens told them such a test was conducted, and that the air was safe, she said. She has asked for a copy of the report, but hasn't received it.

The noise also can be overwhelming, she said. Work often starts around 6 a.m., she said. At that time, "it might be one guy hammering, but it goes through the entire neighborhood." Her children eat breakfast to the beep-beep sounds of trucks backing up.

Clemens said he empathizes with the neighbors, and understands it's tough to live so close to a major construction site.

The city and Skanska Trident try to minimize as much as possible the impact on neighbors, he said. For instance, to alleviate traffic congestion, workers are not allowed to park in the neighborhood or in the parking garage adjacent to the site. Most of them park at off-site locations and are bussed to the site.

Drake said conditions were bad in early stages of construction, but they are improving as the building progresses. There is less dust and noise now that much of the building is enclosed, she said.

The city has been good about informing residents about what is going on, she said. "It's not a perfect world, but it's better when we communicate. We're almost near the finish line."

Reach Diane Knich at 843-937-5491 or on Twitter at @dianeknich.