Co-founders Cameron Sinclair and Kate Stohr, who ran the organisation from 1999 to 2013, responded to the "sad news" in an email yesterday.
"We just heard the news that Architecture for Humanity, the organisation we started more than 15 years ago, has pivoted its mission and is planning to close," wrote the duo, who are pictured above. "We are deeply saddened by this."
Operating under the slogan "Design like you give a damn," AFH raised money to fund architectural solutions to humanitarian crises around the world, raising over $5 million (£3.3 million) in funding each year.
But the organisation's headquarters near Union Square were shut down and all staff laid off without announcement on 1 January, according to the San Francisco Chronicle.
AFH has yet to issue a statement about the reasons behind the move, but board member Clark Manus of San Francisco firm Heller Manus Architects told the San Francisco Chronicle that the organisation ran out of money to fund its projects.
"The board tried very hard to figure out how to right the organization, and we were out there looking for angels, but the money wasn’t there to support it," said Manus. "It's not that the mission and need wasn't clear, or that the staff wasn't dedicated."
The New York Times reported that the organisation intends to apply for Chapter 7 bankruptcy protection after being unable to reduce a deficit of $2.1 million.
AFH's numerous international chapters remain unaffected by the closure, since they operate independently. The organisation has over 20,000 members and 59 chapters, including 18 outside the USA.
"Architecture for Humanity London was sad to learn of the closure of the San Francisco headquarters," said Beth Worth, a trustee for Architecture for Humanity's London chapter.
"However, AFH London is still open for business as a registered UK charity and limited company."
AFH supporters called on the San Francisco office's board to explain their actions.
Jonathan Hursh, founder and executive director of non-profit organisation Included, wrote on Facebook: "As a former partner and current fan of both your work and the founders, [I] would suggest that it would be good for all involved if you can immediately send out communications to your chapters and partners to get ahead of the breaking media news as soon as possible."
"Kate [Stohr] and I can't speak or act for the organisation, due to our departure," Cameron Sinclair told Dezeen, "but it's been amazing to see chapter leaders mobilising in the last 24 hours and making the board be transparent in their actions."
The non-profit organisation was founded in 1999 when Sinclair and Stohr organised a competition to design refugee shelters for Kosovans returning home after the war in their country, but stepped down from the organisation in 2013 to pursue other projects.
AFH regularly ran open design competitions for structures that would benefit vulnerable communities and disaster victims around the world.
Recent projects that feature on AFH's Facebook page, which has not been updated since 11 December, include a school in Peru and a community centre in Slovakia.
It also helped to fund projects such as the Yodakandiya Community Complex (above), which was constructed in Sri Lanka following the 2004 Indian Ocean tsunami and was shortlisted for the 2010 Aga Khan Award for Architecture.
"We ran the organisation and grew it from just a small circle of volunteers to an international organisation with chapters in 25 countries," said the co-founders. "For more than 10 years, together we led the movement to bring social design where it is needed most.
"We built award-winning buildings, ran innovative programs, personally raised more than $5 million in annual funding, year in and year out, and established more than five community design centres that set the standard for rebuilding after disaster."
"We hope the profession will continue to design like a give damn – in whatever form that takes," said Stohr and Sinclair. "And we urge the chapters to continue their much needed work".
Sinclair is now executive director of the Jolie-Pitt Foundation, a non-profit organisastion established by actor Angelina Jolie and dedicated to community development and conservation in Cambodia.