Gwinnett County school board members late Thursday agreed to hire a Lilburn firm to build an addition to Peachtree Ridge High School.

The board voted in favor of A.M. Adams Building Corp. The Lilburn-based company estimated it could do the work at a cost of about $6.3 million, the lowest bid for the project.

Peachtree Ridge High, located in Suwanee, opened in 2003 with an enrollment of about 1,900 students. The enrollment has nearly doubled since it opened, with 3,215 students.