Nearly two decades after the Third Church of Christ, Scientist, decided its downtown building was too costly to maintain and didn't meet its needs, the church has won city approval to demolish the Brutalist-style structure at 900 16th St. NW.

Office of Planning director Harriet Tregoning, acting as the mayor's agent on historic preservation, ruled last week that forcing the church to continue worshipping in the recently landmarked concrete building would create an "unreasonable economic hardship" - in essence, that huge maintenance and repair costs would bankrupt the congregation.

Tregoning, in a 28-page ruling, found that the denial of a demolition permit "would result in the inevitable demise of the Third Church as a downtown congregation."

Her decision is the latest chapter in a tortured preservation case, one that pitted a small congregation - and a development firm it teamed with to redevelop the valuable corner property - against a staunch band of preservationists who said the 1971 building should be preserved as an example of a daring type of modernist architecture.

But the D.C. Preservation League, which opposes demolition of the church, is not ready to give up. Director Rebecca Miller said Monday that Tregoning's ruling was "expected," given the support of city economic development officials for redevelopment of the site. Miller said the league will appeal the ruling to the D.C. Court of Appeals within the next 30 days.

Over the past year, the Third Church dispute has also found its way to U.S. District Court, where church attorneys claimed that the Historic Preservation Review Board's recommendation against a raze permit burdened the congregation's right to free exercise of religion.

One of the church's attorneys, George Keys, said Friday that no decision has been made yet on whether to pursue that suit. But at a preliminary hearing in April, Judge James Robertson refused to dismiss the case, noting that the denial of a raze permit "clearly imposes a financial burden" on the church. Tregoning's ruling, essentially a review of decisions by the preservation board, lays out the case history. The Third Church was founded in 1918 in rented quarters near Lafayette Square. The "mother" Christian Science church in Boston acquired the property at 16th and I streets in the late 1940s. In the 1960s, the mother church retained Araldo Cossutta of the famed I.M. Pei firm to design a new church and offices for the Washington bureau of the Christian Science Monitor, clearly hoping for a bold architectural result.

"The building's design and choice of materials, particularly the use of uninsulated concrete, were experimental and it could not have been predicted when the building opened in 1971 whether it would succeed as a place of worship," Tregoning wrote. "The experiment," she added, "failed badly." Her ruling outlines the nowfamiliar deficiencies: "pervasive structural cracking," water infiltration, breaking concrete on the exterior and uninsulated concrete walls that make it impossible to maintain a stable temperature.

After examining financial data, Tregoning concluded that the necessary repairs and large maintenance and operating costs would eat up all of the congregation's funds. "Even when considering only normal operating costs, the church faces a dire financial situation likely to cause its demise within eight years or less," she wrote.

She rejected the idea that the building could be sold and "adaptively reused" by some other institution or firm. "Adaptive reuse ... is not a viable option" both because of the structural problems and because the design of the building, with one huge sanctuary, is not suitable for alteration, Tregoning wrote.

And because the land under the building belongs to a development firm, ICG Properties, the church has "nothing of value" to secure a loan for updates. "The church has little or no collateral to finance the extraordinary repairs needed, and its members have no interest in paying for measures that would not meaningfully contribute to their worship experience," she wrote. "Nor can the Church walk away," Tregoning continued. "Throughout its history, this congregation has manifested an unwavering intent to remain where it is. Its location is its mission. To leave the area it has served since 1918 would be tantamount to its destruction."

Then she added, "Yet to remain in its present building would have the same result."

Church leaders said in a statement that they will attempt to restart their joint redevelopment plan with ICG "to enhance both of our efforts for a more appealing and useful space on 16th Street," and to finance construction of a new church. "We want to establish a welcoming, open presence on this very important corner of our Nation's Capital," the statement says.

The church is already working with the Kerns Group, an Arlingtonbased architecture firm that is experienced in church design. New construction on the site is still subject to review by the preservation board because the property sits within the 16th Street Historic District.

Tregoning's ruling comes with one caveat: No raze permit will be issued until the church obtains a permit to build a new facility on the same property. The stricture is an attempt to ensure that the landmarked building will be demolished only to make way for a new church, and that the Third Church maintains its presence downtown.

The planning director's handling of the case inspired some controversy. An administrative law judge normally handles such cases, and the preservation groups had challenged the mayor's selection of Tregoning to preside over this one.

In legal motions, the groups said Tregoning had a conflict of interest because her office reports to the deputy mayor for planning and economic development, who publicly supported demolition of the church and redevelopment of the site.

But Tregoning, in her ruling, dismissed the idea that she couldn't hear the case fairly. "Statements by the Mayor or Deputy Mayor cannot be attributed to the Mayor's Agent and do not constitute a showing of personal bias," she wrote.