MANCHESTER — City crews shored up decking around portable classrooms at five schools Monday, making them strong enough to get through the rest of the year, a city official said.

Kevin O'Malley, the director of Manchester city facilities, said the ramps can be put to full use starting today. But he stressed the repairs are temporary, and city school officials must decide whether to continue with the temporary classrooms at the five schools.

Most of the modular classrooms are about a decade old, and it will cost hundreds of thousands of dollars to extend their use, he said.

“These things are nearing the end of their useful life,” O'Malley said.

On Friday, a wooden platform that leads to two portable classrooms at Beech Street School collapsed, sending students tumbling. Twelve suffered minor injuries.

Over the weekend, inspections followed of ramps at Beech Street, Wilson, McDonough, Northwest and Weston schools. Superintendent Tom Brennan closed all portables Monday, as city workers worked to strengthen them.

O'Malley said workers sistered studs to existing posts, replaced some decking and reinforced railings with additional framing.

He said the adjacent portables are in need of roofs, flooring and other maintenance that would amount to a huge investment. Before that work is done, the school district needs to decide whether to continue with portables, he said.

School officials have said they want a redistricting plan in place by September of this year. Such a plan could address portables and crowding at some schools.

Superintendent Tom Brennan has said there is no current configuration of elementary schools that would eliminate the need for portables. Some room might be created, however, if special programs were moved to a different school.

O'Malley attributed the collapse to faulty nails. Although pressure treating preserves outside wood for long periods, common nails corrode and eventually weaken.

Galvanized nails are now used on the decking, O'Malley said. Workers were using screws to secure new decking at Beech Street Monday.

New Hampshire Union Leader reporter Beth Hall Lamontagne contributed to this article.

mhayward@unionleader.com