Crews are now working seven days a week to prepare two dormant public-health buildings in Mattapan for long-term use as for residential programs that had been housed on Long Island.

The city is also looking to rent or buy additional space - including possibly in the closed Radius hospital in Roxbury - for its drug and homeless programs for the several years before the bridge to Long Island can be rebuilt, John Townsend, the Boston Public Health Commission's director of administration and finance, said at a commission hearing this week.

Townsend said both the Mattapan buildings are in the commission campus on River Street. One of the buildings, known as Building N should be open with 74 beds by Nov. 3. It will house house two programs for people trying to re-enter society after substance abuse, one for men nearing the end of prison sentences, the other for people who need a short-term residential program.

The other building, which formerly housed an adult daycare program, should be open early December, with 24 additional beds, he said. The commission had been using the building recently to store old furniture, which workers are now removing.

Townsend said that as hard as the sudden evacuation was, the commission knew the bridge would be closed eventually and had already prepared to some extent - by stocking the South End Fitness Center with supplies to quickly turn parts of it into an emergency shelter and by signing contracts with private shelter providers to take in a number of homeless people until the commission could find additional space.

At its meeting, the commission board went into a closed session to discuss possible deals with landlords for additional space for the programs displaced by the bridge closing.