Under current statutes, those preparing to build must first seek permission from City Hall. They are required to declare their intentions in writing and provide a list of documents, including the building plans and the name of the engineer.
Most people either ignore the law, or go to City Hall well after they've started building, municipal authorities say.
But residents aren't the only ones skirting the law.
The municipal engineering departments are supposed to forward all requests to the Ministry of Public Works for review.
"If there are 500 houses being constructed in Petionville, perhaps they send only three or four to the ministry, " said former Public Works Minister Frantz Vérella.
But even if the authorization is given, there is no guarantee the individual doing the approving at City Hall is qualified to do the job.
For example, while the city of Port-au-Prince boasts three architects, 10 engineers and more than a dozen inspectors in its 30-person city engineering department -- according to its mayor -- many cities and towns have no qualified government engineers.
Cities are not alone in struggling to attract qualified engineers or urban planners. Vérella, who was replaced as public works minister two months ago, estimates there were about 120 engineers in the entire ministry -- and less than a dozen certified urban planners in the entire country.
The southwestern tourist city of Jacmel, population 400,000, has about one government engineer for every 100,000 people, Vérella said. Guadeloupe, the French-speaking Caribbean island with about the same population, has eight per 5,000.
Port-au-Prince Mayor M. Jean-Yves Jason concedes that one of the biggest issues for mayors is the lack of clarity in Haitian law over how much power mayors have over their cities. As a result, mayors say, it's difficult to know to what extent the city or central government is responsible for ensuring building safety.
That leaves it up to residents and local engineers to ensure that projects are structurally sound.
Haitians also say inspections often are nothing more than a means for collecting bribes.
Inspectors are usually on the lookout waiting for individuals to begin to pour a slab. Once they see someone doing so, they ask for a permit. If one cannot be produced, residents say, the construction is blocked.
"They collect and there are a group of men in the mayor's office who collect. . . . That is what they call an inspection, " Vérella said. "There is no one who confirms if the mix is done correctly, if enough cement is being used. There is not a single person who confirms anything. That is supposed to be the job of the municipality, the engineer department."
Jason says his inspectors don't take bribes and points to buildings around the capital sprayed with red paint, indicating to builders that their construction is closed for lack of a permit.
In the days since the second school partially collapsed, Jason said Port-au-Prince has begun to demolish several unsafe homes. The demolition began in the very neighborhood, Canapé Vert, where the second school partially collapsed and was later destroyed.
But entrepreneurs and others who live off the sand in Laboule say demolition is not the answer.
"They should help us, " said Wilma LaPointe, 37, a truck driver who sells mountain sand. "Tell us how to better construct and help us do it."