Renovating historic Altgeld Hall

CHAMPAIGN, Ill. - The slabs of sandstone that make Altgeld Hall one of the most recognizable buildings on the University of Illinois Urbana-Champaign campus have been covered in scaffolding for months. But the results of the renovation work going on there are apparent, as the dark gray stone is restored to a pinkish hue.

Standing near Altgeld, I can see workers high on the scaffolding, cleaning the stone, and I hear hammering coming from the roof. The work is part of a multiphase project managed by the Illinois Capital Development Board that includes exterior and interior restoration of the building. The current phase of the project involves renovation of the building's facade, structural improvements to the bell tower and restoration of the chimes system.

The last major renovation work at Altgeld Hall was in the 1950s, when the math department moved into the building. "Combined with continued enrollment growth and expanded usage, comprehensive exterior and interior upgrades were necessary to modernize the facility with new learning and research spaces while conserving and revitalizing the building's historical features," says Kevin Price, the capital construction project manager for Facilities and Services.

"The renovation of Altgeld Hall will mark the rebirth of one of the campus's most storied and iconic buildings. The facility, which opened in 1897, was instrumental in the university's early growth, and this project ensures that its legacy will continue," Price says.

Every detail of the work has been carefully planned to protect the 127-year-old building and ensure repairs are historically accurate. Project manager Travis Schiess and preservation manager Sarah Horton of Berglund Construction, the firm serving as the construction manager for the project, lead me and photographer Fred Zwicky on a tour of the construction site. Workers are cleaning the sandstone and replacing all the mortar, which is deteriorating.

Schiess says the dark color of the stone is partly the result of soot from a coal-fired power plant that at one time operated just north of Altgeld Hall, near the current engineering quad. Other industrial sources, including a foundry in the area, and wood-burning fireplaces in several campus buildings likely contributed as well. He points out the difference between the dark gray stone on the original north-facing portion of Altgeld, built in 1896, and that on the newest addition on the southeast, built in 1956.

"On this side (of the 1956 addition), it looks like it's already been cleaned, but it hasn't. This was built after the coal-fired plant was no longer in service," Schiess says.

Masons use natural bristle brushes to scrub a gentle, non-abrasive commercial cleaner onto the stone to clean it. Then they rinse it off and test the pH levels of the stone to make sure no cleaner remains. The porous sandstone could absorb the cleaner, which would start to eat away at the stone, Horton says.

The heaviest deposits of soot and grime are scrubbed off, but the workers don't remove every bit of black from the stones.

"Once the project is complete, you will still see some patina on the stones. The goal is to remove the heaviest build up, while not causing damage by using overly aggressive chemicals. The best practice for restoration cleaning is to use the gentlest means possible," Horton says.

Broken or damaged stones are being replaced or repaired. The enormous stones at ground level - 5 feet deep and 6 feet long - are not easily damaged, but the small, intricate pieces of stone in the bell tower are more susceptible to cracking, Horton tells me. The Kettle River Sandstone used to build Altgeld Hall was quarried in Sandstone, Minnesota. The quarry is no longer operating, but there were some large boulders left that were purchased for this project.

As we climb the scaffolding, I watch two masons use trowels to add mortar between the stones, then brush away the excess before it hardens. They are using a custom blend that was made to match the original mortar, which was analyzed microscopically and broken down with acid to see what aggregates were used to make it.

"Mortar should be softer than the stone, and a lot of modern mortars are going to be too hard for sandstone, which is a softer stone, and a historic stone. If it is too hard, it damages the stone. During freeze and thaw cycles, the stone presses into the mortar. If the stone is softer than the mortar, it breaks down, and you want the opposite to happen," Horton says.

Higher up on the tower, I can see holes that have been drilled in the mortar.

"Over time, water finds its way in and some of the mortar breaks down and washes out," Schiess says.

Liquid mortar is injected into the holes to fill any gaps inside where mortar has washed away, he says. The liquid mortar is being used rather than epoxy or other non-mortar product that would allow water to be trapped inside and erode the mortar and stone. The masons working on the project went through specialized training to work on historic structures, and several of them have certification in historic preservation masonry.

As we climb to the top of the tower, near the turrets, Schiess points out a gap between the stone and the mortar. The turrets are starting to shift away from the rest of the tower as a result of the building settling and thermal expansion and contraction, he says. The renovation includes adding vertical expansion joints that are filled with a flexible foam tube rather than mortar, to allow for expansion and contraction.

Altgeld's chimes will be removed by a specialty bell storage and restoration contractor from Indiana - one of only two in the country that does this work. The tower will get a new braced steel frame inside to provide extra stabilization.

On the opposite side of the building, a construction crew is standing on the slope of the roof below the bell tower. They are removing the terra cotta roof tiles and stacking them on planks along the roof. The copper gutters will be removed, and steel supports added on the underside of the roof. The workers are adding a new plywood deck on the roof and unrolling material that serves as an ice and water shield. When they're finished, they'll reinstall the gutters and tiles.

The next phases of the project include building a new Illini Hall and renovating the interior of Altgeld Hall. The math department, which is housed in Altgeld, has made the best of the space that was built in five different stages - but there are no spare offices for new faculty members so the department has to creatively reassign space to accommodate them, and people are spread among nine buildings, says math professor Sheldon Katz. The renovation will address departmental growth and create a student-centered environment, he says.

The work will include modernized classrooms and research labs; an undergraduate lounge and spaces for student clubs and activities; rooms for tutoring and office hours; space for the NetMath online learning program; accessibility improvements; life-safety upgrades; and enhancements to building systems for energy conservation benefits.

Even the exterior work will improve the experiences inside Altgeld's classrooms and offices - currently, staff and students must contend with the realities of maintaining a historical building, including a periodically leaking roof, Katz says.

"It has been intentionally designed to really reimagine the building and construct it to enhance the student experience," Katz says. "It's very rare for a math department to be able design a building for what we do. It's very exciting."