A roof sculpture at the Corcoran Gallery of Art. (Astrid Riecken/FOR THE WASHINGTON POST)

At the heart of the controversial argument that the Corcoran Gallery of Art and College of Art and Design must consider moving from its building is a number: $130 million. That’s the estimated cost of renovating the landmark, according to Corcoran executives.

Some critics of the possible move seized on the number as perhaps inflated to make a change of location seem inevitable. After providing scant details immediately after their bombshell announcement, Corcoran officers described components of the estimate in recent interviews with The Washington Post.

According to a summary of a plan by a construction estimating firm with museum experience, the Corcoran needs a range of renovations, including a new cooling unit ($1.5 million) and a boiler ($400,000), a new skylight roof over a wing that was not re-roofed during a project a few years ago ($11 million) and a museum-wide fire-suppression system that would use high-pressure technology to produce a water vapor that would not damage paintings ($28 million).

The scope of the four-year project paints a portrait of a 115-year-old museum building in which critical maintenance has been deferred for decades. It also suggests an institution with ambitious — and expensive — goals.

Broadly speaking, the cost per square foot appears higher than recent large Smithsonian renovations. However, few projects are perfectly comparable; the Smithsonian projects, for example, have involved newer buildings.

One of two U.S. flags currently placed on the 17th Street side of the Corcoran Gallery. (Astrid Riecken/FOR THE WASHINGTON POST)

“The numbers don’t stagger me,” said David Greenbaum, an architect and vice president with the SmithGroupJJR in the District who specializes in cultural projects, including Smithsonian renovations. He was part of a team of restoration architects who helped the Corcoran a decade ago, when an expansion designed by Frank Gehry was planned.

“The numbers can be fairly high-reaching if the scope of the work is very intensive,” added Greenbaum, who has not seen the new report.

“That’s a very big number,” said David Levy, former director of the Corcoran who resigned in 2005 when the board of trustees killed the Gehry project. “Without knowing the scope of what they have in mind, it’s very difficult to speak to it.”

He added: “My instinct would be you could do it for less. But I can see how you’d get to that number if you looked at everything that needed to be done.”

Nonetheless, some line items might spark debate. For example, Smithsonian museums have not invested in building-wide vapor sprinkler systems. Instead, they use less expensive water sprinklers designed for museums. The Phillips Collection also has a museum-quality water sprinkler system. The National Gallery of Art uses a mist system only in certain areas.

The Corcoran has sprinklers in only parts of the building, and they are dated.

“If we’re going to sprinkle the building, let’s sprinkle it in a way that has as low a probability of destroying the art as possible,” said Fred Bollerer, director of the museum. “If there’s just a marginal difference in price, I would rather go with something that is really state of the art.”

Partial and incremental fixes have been the rule at the chronically cash-strapped Corcoran, said Harry Hopper, chairman of the board of trustees. Mechanical, electrical and safety systems are interrelated, and if the gallery and school were to stay put, he said, it would make sense to do everything that needs doing.

“With enough resources, we would relish the challenge to restore the existing building and adapt it to the new vision,” Hopper said. “However, it would be irresponsible of us to go out with a plan that required a level of funding that was not attainable.”

The renovation estimate was produced late last year by New York-based Stuart-Lynn Co. The firm’s projects have included the Whitney Museum of American Art and the the Morgan Library and Museum in New York City; the Johnson Museum of Art expansion at Cornell University; the Miami Art Museum; and the Clark Art Institute in Williamstown, Mass.

The Corcoran is “a lovely, beautiful building from which [museum managers] could derive a spectacular institution, with time, and the proper capital,” said Breck Perkins, technical partner at Stuart-Lynn. “Their maintenance staff has done yeoman’s work in trying to keep this building together.”

The repairs included in the estimate largely came from a to-do list provided by the Corcoran’s facilities staff, Perkins said.

The construction costs alone total $102,178,268.

In addition, “soft costs” — such as architectural design and engineering — are calculated at about 30 percent of construction. The total project cost is $130 million.

Perkins said the 30 percent figure for soft costs is an industry rule of thumb.

At the Smithsonian, project planners estimate soft costs at 20 to 30 percent, depending on the project, said Walt Ennaco, director of planning and project management.

The $130 million total would cover 129,010 square feet of usable space, or $1,008 per square foot.

The Smithsonian spent $85 million from 2006 to 2008 to renovate the core of the National Museum of American History, built in 1964. That project covered about 120,000 usable square feet, for a cost of $708 per square foot, not adjusted for inflation.

The four-year Corcoran project would be divided into three phases. The first would include such items as upgrading heating, ventilation and air conditioning (HVAC). HVAC is critical to a museum. Relative humidity must be kept at about 50 percent and temperature at about 70 degrees.

The second phase would include complying with public accessibility rules under the Americans with Disabilities Act. The Corcoran, like many historic buildings, has a waiver to operate with limited accessibility. Renovation cancels the waiver.

The third phase would include demolishing and rebuilding the college space in the basement.

The $130 million total is significantly higher than a 2005 estimate of $35 million to $40 million to repair the building. Former board chairman John “Til” Hazel gave that estimate to The Post at the time. Bollerer, who came to the Corcoran in 2009, and Hopper, who joined the board in 2005, say that they don’t know what the earlier estimate was based on.

“That probably came off the back of my envelope,” Hazel said Tuesday.

Back then, Hazel said, he was focusing on immediate needs and did not undertake a detailed study. “The whole question of the building and what to do for the long term was ahead of us.”

Still, the scope and details of the $130 million project leave much open to debate.

“How much of this has to get done now versus over the years?” said Jayme McLellan, an organizer of Save the Corcoran, the group of artists trying to stop any plan to sell the building. “The way to do that and the way to reinvent is through a capital campaign and reinvention of leadership. . . . People who know the Corcoran know that everything hasn’t been tried. ”

The problem with stringing out the work over more than the projected four years is that it could involve moving the art and the college in and out of the building more than once, Bollerer said. As it stands, the college would be relocated for the entire four years and portions of the gallery, if not the whole gallery, closed for extended periods, he said.

Not included in the $130 million estimate is the cost of temporarily relocating the college and the artwork; the cost of finding satellite space to fulfill the Corcoran’s ambition to expand the college; and the cost of Bollerer and Hopper’s vision of reprogramming the Corcoran to become primarily an educational institution, with the 16,000 art objects placed in more direct service of educating students and the public.

“If we actually included all of those things, it’s a substantially larger number,” Hopper said.

Hopper and Bollerer said they doubt the Corcoran would be able to raise such a sum so soon after failing to raise about $200 million for the Gehry project in 2005. (Levy estimates the cost of the Gehry plan at $160 million.)

“What we have learned from past initiatives is that it would not be responsible or credible to take on a $200 million campaign, which is the order of magnitude necessary to a long-term solution to staying in the building,” Hopper said. “We are not going to preside over another Band-Aid approach.”

Important questions linger: How much would selling the building yield? And what would it cost to move to a new location, possibly in the suburbs?

Bollerer and Hopper said they won’t know until the process of testing the market and scouting locations is further along.