interstitial space

Interstitial space is the gap between the cleanroom ceiling and building structural ceiling, housing mechanical equipment and utilities. **Purpose**: Contain HVAC equipment, ductwork, FFUs, piping, electrical, and service access without cluttering the cleanroom below. **Access**: Often walkable space for maintenance access to FFUs, filters, and utilities. Grated walkways over ceiling panels. **Height**: Typically 3-12 feet depending on equipment needs. Larger fabs may have very tall interstitial spaces. **Contents**: FFU motors and plenums, ductwork, sprinkler systems, lighting electrical, process piping, utility connections. **Maintenance**: Technicians access from above to replace filters, service FFUs, repair utilities without entering cleanroom. **Cleanliness**: Not cleanroom environment but kept reasonably clean to prevent contamination of air supply. **Fire suppression**: Separate fire detection and suppression for interstitial space. **Vibration**: Equipment mounted with vibration isolation to prevent transmission to cleanroom below. **Design integration**: Planned during fab design, structural ceiling must support interstitial equipment loads.