NORTH ANDOVER — Some worked through the night. Others were scheduled to head back to the station later in the day.

But that didn't stop a dozen off-duty firefighters from heading to Grogan's Field every morning with their ladders, power tools and wheelbarrows.

This makeshift crew spent all last week gutting the shack that sits in left field and rebuilding its roof.

It is a labor of love.

The little red building off Baldwin Street has been falling apart for years, but there was never any money in the budget to fix it up.

Once part of the old Johnson High School, it housed athletic offices, showers and bathrooms. Now, in its crumbling condition, it is mainly used to store equipment, the only occupants some squirrels and birds.

"The way the building is today you wouldn't want to put a kid in there. It's dark and dirty. Everything was broken," said Booster Club President Terry Holland. "We wanted to make it a place for kids again."

Holland and the firefighters, led by Gary Wentworth, hatched a plan. They asked the town's Community Preservation Committee for $45,158 this year — just enough to cover building materials.

And the firefighters pledged to fix it up themselves.

"They have a lot of talented people in the department— plumbers, carpenters, electricians," Holland said. "They said, 'We'll get this thing done and done right.' ... They're looking for nothing. They just want to help the community. As if they don't do enough."

The firefighters say they will spend the entire winter — and into the spring if they have to — making the building suitable for children again.

Besides replacing the exterior siding and adding new doors and windows, they plan to install handicap accessible ramps and bathrooms, and upgrade the plumbing and electrical system. Workers from Testa Construction in North Andover, booster club members and Public Works employee Ken Wedge are all lending a hand as well.

"It just feels good to give back," fire Lt. Robert Bonenfant said, before climbing onto the roof with his tools, country music blasting in the background. "And we're having some fun doing it."

The town moved the athletic building from the high school to Grogan's Field years ago, giving the historic shack a new use instead of destroying it. It was the building's history that has now secured its future.

Since the shack was part of the old high school it is considered historic and qualifies for Community Preservation Act money. The Community Preservation Act adds a 3 percent surcharge to all property tax bills with the money to be used for historic preservation, affordable housing and open space.

Town Meeting voted to use CPA funds for this project in May.

Holland said once the building is done, more than 1,000 children will likely be using it every year.

The high school, North Andover Booster Club and other youth sports leagues can use it during games and practices. And Youth Services, which uses the field and playground to host programs for neighborhood children, can use the building for indoor activities.

Wentworth, Bonenfant and firefighters John Weir, Rich Bradley, Sean Bushnell, Dan Pas, Mike Risacher, Jack Risacher, Bill McCarthy, Jeff Crosby, Graham Rowe, Rob Hardacre and Liz Iminski all volunteered.

Ken Wedge watched as they worked through the morning, not one complaint as they put down new sheets of roofing and carried out boilers and other cobwebbed equipment to be hauled away.

"A lot of these guys could have taken on overtime shifts, but they came here to volunteer," he said. "It's a wonderful thing."