This process is going to add even more meetings to your day. It's critical that the library director participates in as many of the committees and subcommittees as possible, and keeps tabs on the others.
This is the overarching, decision-making body that oversees the project. All the work of the subcommittees is brought to the main Building Committee for approval and formal submission to the library Board of Trustees or the city/town, depending on your local process.
Many towns and cities have standing building committees for all public construction projects.
Every project is different, but some of the common subcommittees are: