D.C. Mayor Vincent C. Gray and Interim Chief Librarian Joi Mecks announced Tuesday the winners of a design competition to renovate and possibly add floors to the Martin Luther King Jr. Memorial Library downtown.

The winning firms are the Dutch company Mecanoo and D.C.-based Martinez and Johnson Architecture. Like the competing teams, Mecanoo and Martinez-Johnson were asked to design both a stand-alone renovated King library and a version with additional floors for office space or housing that could produce tax revenue for the city.

Here are some of the renderings from the winning proposal:

Gray issued a press release saying the choice marked “another step towards giving our residents the great central library they deserve in a way that helps improve both the public’s library experience and our library system’s bottom line.” The mayor and the D.C. Council have already approved $103 million for the project, though that is likely to be half or less of the final development cost depending on the final design.

Building new floors on top of the library would create valuable real estate in one of the most prime markets of the city and even the region, but doing so requires leaping a number of logistical hurdles.

Philip Kennicott, the Post’s architectural critic, wrote last week that all three finalists seemed to struggle with redesigning the 1972 building to both modernize it to provide contemporary library services and add a private addition.

Beyond that, Robin Diener, the president of the Friends of Martin Luther King Jr. Memorial Library, a private non-profit founded a few years ago, would like to see the building remain completely dedicated to public uses. The group has no formal control over the process, but Diener is not easily dissuaded; she is also executive director of the Ralph Nader-founded group that has pushed for greater accountability in redevelopment of D.C. libraries. The group  successfully delayed some of them, such as the rebuilding of the West End library, for years with lawsuits and administrative challenges.

“I like the winning design very much and I like the architect very much,” Diener said of the selection in an interview. She said she could envision supporting just the renovation of a stand-alone library or adding additional floors on top but she didn’t see why those floors needed to be added to raise money —  the reason the idea was proposed in the first place.

“Certainly we can do [add floors] but if we go for a development on top I would like to see something that is a public use and the question then is how we pay for it and if there is a way to pay for it, and I think there is,” she said.

“We may not need to go for any public-private partnership,” she added. “We’re in a very good position in the city financially. There is absolutely no reason we couldn’t do it.”

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