Concord families returning to Thoreau Elementary School on Aug. 31 found a key wing still shuttered, four months after a fire tore through the building's attic.

Concord Public Schools Superintendent Laurie Hunter told the School Committee on Aug. 26 that the repair project has fallen behind schedule. The district determined it must replace the entire fire suppression system before reconstruction can begin, The Concord Bridge reported.

"Unfortunately, the fire wing is not back on track," Hunter told the committee.

The district now hopes to reopen the damaged section in October. Hunter said that timeline could slip to November.

To keep classes running, the district worked with its insurer to place two modular classrooms behind the school. One houses a second-grade class. The other serves as flex space for displaced programs.

The fire broke out the evening of April 27 in an attic above classrooms in the 1994 wing of the Prairie Street school. Fire Chief Brian Whitney previously told The Concord Bridge that a supplemental heating unit, used to keep sprinkler pipes from freezing, probably started the blaze. Investigators ruled out other causes.

Sprinklers contained the flames but sent water cascading into classrooms below. Four rooms required repairs down to the studs, and four others sustained additional damage. Joint School Committee minutes from May 6 show the sprinkler activation displaced 13 rooms in total.

The April fire was not the building's first brush with its heating system. A similar fire in 2021 led to months of repairs. In 2023, insufficient heat allowed pipes to freeze and burst.

Hunter said the district plans to replace the existing wet fire protection system with a dry system, eliminating the need for heaters in the attic. Insurance will cover the repairs and replacement of damaged materials, so the project will not significantly increase the operating budget. The modular classrooms will add a minor electricity cost.

The district had planned to pave Thoreau's parking lot but deferred that project, redirecting those capital funds toward the new suppression system.

At the May 6 Joint School Committee meeting, Thoreau parent Shuchi Sharma praised the school's staff and custodial team. She noted they relocated eight classrooms and reworked logistics within a single day to keep the school open after the fire.

Construction on the second phase of Thoreau's playground, including a new nature space, began in early August and is expected to continue into October.

Hunter said as of Sept. 7 that the district expected to finalize the suppression system's design that week. The design would give officials a clearer cost estimate for the project.