Firefly Aerospace Hive Cleanroom 3

Firefly Aerospace is building a 14,168 sq ft addition to its existing Hive facility at 5900 183A Toll Rd in Leander, Texas. The project, filed as Firefly Aerospace Hive Cleanroom 3, involves the design and construction of a new cleanroom and associated spaces. The estimated cost for this expansion is $4,700,000, which works out to $332 per square foot.

The work is classified as additions to an existing building in Williamson County. Fuse Architecture Studio is the design firm of record for this project. Mark S Robinson serves as the registered accessibility specialist. The project is privately funded and located on private land for private use. Firefly Aerospace is the owner and developer of record.

Project Scope and Cost Context

The scope of work specifically includes the design for the addition of a new cleanroom and associated spaces at the existing Hive facility. This project is part of a broader portfolio for Firefly Aerospace, which has four other TDLR-registered projects totaling $18,000,000 in Bertram. The current Leander project stands out for its scale and cost relative to local norms.

Among 345 TDLR-registered additions to existing buildings in Williamson County, this project’s estimated cost is above the county median. The median cost for similar filings is $500,000, while this project is valued at $4,700,000. The median size for these projects is 4,792 sq ft, whereas this addition is 14,168 sq ft. The cost per square foot of $332 is also above the county median of $164 per square foot.

Timeline and Status

The project was registered with TDLR in December 2025. Plan review was completed in January 2026, and construction was scheduled to start in January 2026. The scheduled completion date on the filing is May 2026. However, TDLR has not yet recorded a final inspection, so the current state of the site is not confirmed in the public record. The scheduled build window of 119 days is shorter than the county median of 206 days for similar projects.