URBANA — The sagging floors are gone, replaced with gleaming terrazzo and bamboo.
High-tech classrooms and modern labs with touch-screens and data ports line the hallways.
An intricately carved oak staircase has been restored and replicated, and an old museum is now a spacious student hub.
After years of planning, construction, unexpected setbacks, budget increases and even a small fire, the oldest academic building on campus will reopen this summer following a $78.3 million renovation.
Faculty will begin moving back into the Natural History Building on May 16, just after the UI commencement. Classes will resume next fall in the historic building at 1301 W. Green St., U, next to the Illini Union.
"It's effectively just been an amazing transformation from this crumbling relic that we lived in for decades to what I think is going to be a gem of the campus," said Professor Stephen Marshak, director of the School of Earth, Society and Environment. "I think everybody involved is pretty delighted, despite all the bumps and challenges along the way, which were numerous."
Built in the 1890s, with several later additions, the landmark structure designed by architect Nathan Ricker is the third-oldest building on campus.
Engineers inspecting the building in June 2010, after termite damage was found, discovered structural problems with the concrete floors in the 1908 addition on the south and west sides. The floors were sagging because concrete had been poured incorrectly and wasn't reinforced, but the damage was hidden inside dropped ceilings and hardwood floors for more than 100 years.
About half of the building was closed and the renovation fast-tracked.
But a state procurement board's questions about a potential conflict of interest with BLDD architects forced the UI to switch firms and delayed the project by a year.
Then crews discovered that the floors were worse than inspectors thought, literally bouncing when someone jumped on them. Damage from termites and a 1990 fire was also more extensive than expected.
Later, when the new concrete floors were poured, they released excess water vapor, delaying installation of the flooring on top, Marshak said. They had to be sandblasted and sealed first.
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True to its original name, the building will house units that deal with natural history.
The School of Integrative Biology will occupy the original north end, with all of its teaching consolidated there. The School of Earth, Society and the Environment — which includes geology, geography and atmospheric sciences — will take up the southern two-thirds, though the two units will share some classrooms. An auditorium that seats 300 will be for general campus use.
Marshak estimated as many as 1,500 students will pass through the auditorium each day.
"It's going to be one of the most heavily used buildings on campus, which is what it was before," he said.
He is hopeful the renovation will make his programs more visible and help with recruiting.
The rooms are designed to fit 21st-century teaching, with collaborative classrooms rather than standard lecture halls.
One large interactive classroom, Room 2020, is filled with four projectors and drop-down screens that students can use to project data or illustrations. Tables are set up so students can work in groups, and 14 TV screens line the room. It can accommodate 90 students at once, or divide into two rooms with 30 and 60 students, respectively.
All of the labs in the building were designed by faculty for specific purposes, Marshak said. But they're flexible so that several faculty members can share them, and they can change as research projects grow or enrollments shrink, he said.
In the basement, a new atmospheric sciences lab will allow students to assemble weather-measuring instruments, "a whole new generation of classes that we've never been able to teach before," Marshak said.
Another room, painted black, is the 3-D visualization lab for atmospheric sciences, which will allow students to "walk" inside a tornado or other weather systems using satellite data. Across the hall, the new cyber Geographic Information System studio will use Blue Waters' supercomputing capabilities to manage big data to produce visual maps.
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Every interior wall in the building is new, and many were reconfigured. At one point, "you could stand at the north end of the building and see the south end. All the walls were gone," Marshak said.
But architects were careful to reuse many of the century-old features — most of the woodwork and trim, all the doors, several staircases and many of the original windows, even some that face interior hallways or now have walls behind them.
The dramatic main entrance, on the north, opens up onto a wide foyer and the building's original grand oak staircase — or at least half of it.
Architects who dug up the original plans found that there had been two stairwells in the building, but one was removed in the 1950s or 1960s and turned into offices on every floor, Marshak said.
So carpenters made a three-dimensional image of the original half, then used modern woodworking machines to laser-cut the shapes for the other side, which was "completely carved brand new," he said.
Terrazzo flooring now runs through much of the building, except for the north end, where the old wood beams were too flexible, Marshak said. His unit pushed for a renewable flooring product, bamboo, rather than wood.
On the third floor, an area in the middle of the building that used to house the Natural History Museum is now a student commons. The center retains the original vaulted ceiling and old-growth oak floors that once lined the hallway outside.
The outdoor area that formerly surrounded that part of the building has been filled in and covered with a new roof with skylights, allowing natural light into the commons and offices below and making the building more energy-efficient.
The building now has three elevators so it's fully accessible, he said.
The campus funded the project but hopes to raise $7 million from donors.
"Fortunately because there's no state money involved, the building wasn't stopped by the state budget issues," Marshak said.
Other highlights of the newly renovated Natural History Building, courtesy of geology Professor Stephen Marshak:
— Giant dinosaur fossils that once towered over the main-floor west hall will be reinstalled — if they still fit through the doors.
— The entrance to the building's new auditorium will feature a "hyperwall," screens linked together that can show ocean currents, atmospheric circulations and storms.
— Outside the new student commons — once the Natural History Museum — fossil and rock specimens will be displayed in new oak cases crafted by the UI woodworking shop.
— One section of the new terrazzo floors stands out because of its bright colors, designed to represent the geological time scale of the Earth. The largest and oldest, the precambrian period, is red, followed by smaller patches of blue, green and gold for the paleozoic, mesozoic and cenozoic eras.
— A former balcony just above the fourth floor was reconfigured into graduate-student offices with interior windows overlooking a hallway. The glass is etched with a sun design, mimicking the design over the main entrance to the building.
— Polished limestone on the walls in the stairwells is original — to the restrooms. It was originally used for the bathroom stalls, common in early 20th-century buildings. The limestone was cleaned and refinished "so there's no trace of its former use."