“Part of our thought process was that if this is a truly sustainable organization, it should survive without its founders, and 15 years was a good time for that to happen,” Mr. Sinclair said in an interview last week. “We never had a deficit for 14 years, we grew exponentially. Our biggest problem was, I think we grew too quickly.”

Eric Cesal, the most recent executive director, said that the shortfall reached $2.1 million at the end of 2013, an untenable sum for an organization whose annual operating budget ranged from $2 million to $12 million, depending on the scope of projects in a given year.

Ms. Stohr acknowledged in an interview that the organization “had some debt” but said “we were figuring out how to correct that.” She added that, contrary to the assertions of some former staff members, Architecture for Humanity did not promise more than it could deliver.

“There were lots of projects we said no to,” she said. “Some projects were too small or the timeline was hard or we did not have the right staff person or it was an insecure place to work.”

For many volunteers and staff members, the organization — whose prominent financial backers included the Clinton Foundation and the Curry Stone Foundation — was an inspiring vehicle for using design skills for something broader than showy buildings underwritten by corporations or wealthy individuals.

Mr. Sinclair told The Guardian in 2006: “Think about a prestige architect like Zaha Hadid. There are probably 20 people in Britain who can afford to commission her. I, on the other hand, have somewhere between four and five billion people on the planet who are looking for my help..”

Among the group’s projects were a soccer field in Rwanda built to help unite members of the Hutu and Tutsi tribes, and the Football for Hope program — with FIFA and streetfootballworld — which builds community centers in Africa.

Several projects remain undone: a school in the Philippines; a joint project with Nike to rebuild the disaster-stricken area of Tohoku, Japan; and renewal efforts in New Jersey areas damaged by Hurricane Sandy and parts of Oklahoma hit by tornadoes.

“There were definitely cost overruns on projects,” Mr. Charney said, adding, “I hope that issues that have caused the closure, while important, I hope the overwhelming good that Architecture for Humanity has done can overshadow that. We’re proud of the work.”