Officials from the migration agency said they were hoping to give people the means to create temporary housing, and the power to build where they wanted. They acknowledged that it could be five years before most people moved back into houses, which means that under the current best-case situation, Port-au-Prince, Haiti’s capital, will soon be blanketed with hundreds of thousands of simple structures that designers describe as “garden sheds” and others see as shanties.

Image A NEW DAY IN HAITI First graders sang “Frère Jacques” as a school prepared to open in a tent city in Port-au-Prince. Credit... Ruth Fremson/The New York Times

It reflects what emergency shelter experts here describe as an emerging consensus, born in part from the aftermath of the Asian tsunami in 2004. There, aid groups that built concrete homes in large tracts found that few people were interested in moving from where they had lived before the disaster. Transitional shelters were quicker to set up and allowed people to stay put while continually improving their own homes over time.

The model, cited by a senior shelter adviser, is Sri Lanka, where residents using building materials and design guidelines from aid groups built 56,000 transitional shelters in seven months, housing 92 percent of the displaced families in about a 550-mile area.

But in Haiti, the challenge will be even greater. There is a hard deadline: hurricane season starts on June 1. And compared with Sri Lanka, there are far more Haitians without homes, and in a densely packed urban area with rubble crowding nearly every street.

Mr. Turner, along with Haitian government officials, said that the shelter plan would work only if demolition and debris removal moved quickly.